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Titanium Alloys for Aerospace Applications
Advanced Engineering Materials
Abstract
There is probably no other material more closely related to aerospace than titanium and its alloys. With a density of 4.5g/cm3, titanium alloys are only about half as heavy as steel or Ni-based superalloys, yielding an excellent strength-to-weight ratio. Furthermore, they have exceptional corrosion resistance. The use of titanium alloys in the aerospace sector will be highlighted including airframe, engine, helicopter, and space applications.
... Each class of these alloys has distinctive characteristics [14][15][16][17]: (i) α alloys have good strength at elevated temperatures, good weldability, and fair fabricability, but they do not respond to heat treatment; (ii) α + β alloys, on the other hand, have good thermomechanical and heattreatment response to obtain the desired volume/weight fractions, size and morphology of α and β phases, good thermal stability, fair-to-good fabricability, and generally poor weldability; and (iii) near-β and metastable β alloys are amenable to heat treatment and have excellent fabricability and good weldability in annealed conditions, but poor creep strength. Further, it is essential to mention that many research articles, including reviews [18][19][20][21][22][23][24][25][26][27] have shown excellent correlations of processing, microstructure, and properties of different classes of titanium alloys and applications in many aircraft parts. For example, most of the aircraft landing gear parts have long been produced from Ti alloys, viz., Ti5Al5V5Mo1Cr1Fe (VT-22 or BT-22), a basis for Ti-5553, is widely used in landing gear, load-bearing fuselage components, and high-lift devices of Russian wide-body aircraft; and Ti55531 with the addition of 1 wt.%Zr is used in Airbus A380 landing gear parts [27]. ...
... Thus, it appears that the top-ranked alloys arrived at using the MADM approach with the easily available attributes of d, YS, and %EL seem to show that the other attributes like fracture toughness and fatigue would likely meet the requirements for the intended application for these alloys having some basic similarities concerning chemistries, thermomechanical processes, and microstructures, as suggested above. Further testing of the top-ranked alloys for fracture toughness, fatigue, corrosion resistance, etc., is recommended to complete the comprehensive assessment as indicated in some of the research work [18][19][20][21][22][23][24][25][26][27]30,52,53,82,[84][85][86]. The corrosion resistance of these alloys is also expected to meet the requirements. ...
Titanium alloys, with their low density, exceptional mechanical properties, and outstanding corrosion resistance, play a vital role in various aerospace applications. Our decision science-driven assessment focused on metastable β, near-β, α + β, and near-α Ti alloys for landing gear applications, integrating multiple-attribute decision-making (MADM) methods, principal component analysis (PCA), and hierarchical clustering (HC) is based on current literature. The ranks of the alloys evaluated by diverse MADM methods were consistent. The methodology identifies five top-ranked Ti alloys assists and verifies the guidelines for alloy design. The top-ranked alloy, Ti1300-BM-nano-α (alloy chemistry: Ti-5Al-4V-4Mo-3Zr-4Cr, solution treatment: 800 °C for 1 h followed by air cooling—solution treated below β transus, and aging: 500 °C for 4 h followed by air cooling), stands out with a percentage elongation (%EL) ~3.3 times greater than the benchmark or goal (density, d = ~4.6 g/cm3; yield strength YS = ~1250 MPa; %El = ~5), while maintaining similar density and yield strength. The analyses underline that metastable β Ti alloys comprising globular primary α + trans β matrix coupled with α precipitates in trans β are the base optimal microstructure to fine-tune using thermomechanical processing for aircraft landing gear applications.
... Titanium and its alloys have distinguished properties such as high mechanical strength, lightweight, low density, corrosion resistance, and composite capability. These qualities of titanium alloys make them excellent candidates for use as a manufacturing material in aerospace, automotive, and marine applications [10][11][12][13]. Ti-6Al-4V is a frequently used material with distinctive properties with a chemical combination of 6.0% aluminum, 4.0% vanadium, 0.25% iron, 0.2% oxygen, and the other proportion consists of titanium [14]. ...
The present study demonstrates laser bending which is a flexible and (external) tool-free method for bending and shaping of metallic components. The numerical and experimental analysis of the bending behaviors of Ti-6Al-4V titanium alloy sheets has been done under the constant line energy concept. Numerical simulations using Abaqus examine the transient temperature fields, thermal stress, strain, and deformation characteristics. To validate the numerical calculations and observe the effects of process parameters such as laser powers and scanning speeds on the bending capability, the experimental analysis has been conducted and compared with the numerical simulations. In addition, the influence of laser irradiation on the surface morphology of the laser-scanned specimens has been observed by scanning electron microscope (SEM). The findings show that higher line energy causes significant enhancement in bending deformation. The maximum numerical and experimental bending angles of 0.91° and 0.88° have been observed at the line energy of 15 J/mm, respectively. The average percentage deviation of 5.24% has been observed between the numerical and experimental results at the line energy of 15 J/mm. Moreover, melting, thermal oxidation, and crack propagations have been observed during the SEM analysis at high laser power. The numerical simulation and experimental outcomes are helpful for the selection of optimum process conditions in the laser bending method of Ti-6Al-4V sheets.
... Advanced aerospace components, including impellers, turbine blades, and airfoils, are manufactured using the material Ti-6Al-4V, exploiting the benefits of AM technology [6,8]. LPBF technology is the most adequate fabrication technique among the other metal AM techniques due to its capability to fabricate very fine features which is also termed as the resolution [9]. ...
Ti-6Al-4V with its eclectic array of excellent properties along with the combination of meticulous precision and flexibility offered by the laser powder bed fusion (LPBF) technology makes it a strong proponent in the field of engineering applications. As a substantial amount of research has paved the way to fabricate Ti-6AL-4V more effectively and efficiently, researchers are becoming more adventurous in finding out the optimal techniques to get better yields in terms of mechanical responses. This includes post-processing techniques i.e., heat treatment (HT) or introducing various alloying elements. Nevertheless, these techniques not only make the overall fabrication more expensive and time-consuming but also contradict the simplistic notion of additive manufacturing (AM) by imparting multistage fabrication without a considerable improvement overall. Here, we propose an innovative breakthrough in the field of Ti-6AL-4V fabrication with LPBF by introducing an in-situ approach to tackle the handicap mentioned in contemporary studies. By imparting multiple laser scans prior to and after the melting scan at each layer, a remarkable 37% improvement in yield strength (YS) can be achieved with higher elongation, while also maintaining a high relative density of around 99.99%.
... Havacılık, uzay, denizcilik ve tıp endüstrileri çoğunlukla bu araştırma faaliyetlerine odaklanmaktadır. Günümüzde yüksek mukavemete sahip olan Ti-6Al-4V alaşım malzemesi türbin kanatları, roket motorları ve uzay araçları gibi havacılık ve uzay uygulamalarında kullanılmaktadır [5][6][7]. Ti-6Al-4V malzemesi zayıf termal iletkenliği [8], işleme sırasında yüzeyde sıcaklık artışı [9], kesici takımda kullanımında yüksek aşınma [10,11] ve ayrıca yüksek sertlik gibi olumsuz özellikleri bu malzemenin geleneksel yöntemler ile işlenmesini zorlaştırmaktadır [12,13]. İmalat yöntemi, malzemelerin mekanik özelliklerini ve yüzey kalitesini önemli ölçüde etkilemektedir [14]. ...
Ti-6Al-4V malzemesi sahip olduğu yüksek mukavemet, düşük yoğunluk, yüksek sıcaklık mukavemeti ve mükemmel korozyon direnci gibi özelliklerinden dolayı havacılık ve uzay sektöründen medikal sektörüne kadar nitelikli alanlarda yaygın kullanılmaktadır. Uçak türbin kanatçığı, uçak yapısal bileşenleri ve roket motoru gibi geniş kullanım alanına rağmen işlenmesi, üretilmesi ve yüzey iyileştirmesi geleneksel yöntemler ile zor bir malzemedir. Bu ve benzeri işlenmesi zor malzemelerin istenilen yüzey kalitesini elde etmek için aşındırıcı macunla işleme (AMİ) ve bilyeli dövme işlemleri gibi geleneksel olmayan yüzey işleme yöntemleri kullanılmaktadır. AMİ prosesinin yüzey bitirme ve bilyeli dövme işleminin basma yönünde artık gerilme oluşturma kabiliyetlerinin birleştirilmesi ile yeni geliştirilen akışla dövme (GOV) prosesi, elektriksel tel erozyonla kesilerek hazırlanmış Ti-6Al-4V malzemesinde deneysel kıyaslamalı çalışılmıştır. Yüzey pürüzlülüğü, yüzey kalitesi, malzeme kaldırma miktarı ve beyaz katman tabakasının kalınlığını değerlendirmek için GOV ve AMİ işlem parametrelerinin, malzeme yüzeyi üzerindeki etkileri incelenmiştir. GOV prosesinde en iyi yüzey pürüzlülüğü Ra 0,92 um ve malzeme kaldırıma miktarı 3,6 mg olarak, AMİ işleminde ise bu değerler Ra = 0,53 um ve 1989,15 mg olarak elde edilmiştir. GOV işlemi, daha az talaş kaldırarak yüzey kalitesini iyileştirirken, AMİ işlemi çok daha fazla talaş kaldırarak yaklaşık yüzey kalitesine ulaşmaktadır.
... Titanium alloys are important structural materials for numerous applications due to a unique complex of physical and mechanical properties, as stated by Lutjering and Williams [1]. The engineering application of these alloys according to Peters et al. [2] is primarily based on their high specific strength well-balanced with other mechanical characteristics. That is why by Niinomi [3] titanium alloys are used in the biomedical, and based on Jones et al. [4] in aerospace, automotive, and military products. ...
... Due to its favorable attributes including excellent corrosion resistance, high strength at elevated temperatures, good biocompatibility, and superior strength-to-weight ratio, the Ti6Al4V alloy is extensively used in the chemical, marine, biomedical, and aerospace industries [17][18][19]. This alloy is constituted of alpha (α) and beta (β) phases, exhibiting high strength and structural efficiency suitable for highperformance functional applications [20]. ...
Achieving 3D-printed Ti6Al4V alloy with customized microstructures and mechanical characteristics remains challenging, wherein the processing efficiency mainly depends on the laser energy, mass deposition rate, and duration. Based on these factors, a simple and eco-friendly direct laser metal deposition approach was followed to get 3D-printed Ti6Al4V alloys at various laser powers (300–500 W). Herein, a 1.5-kW continuous fiber laser with a wavelength of 1080 nm was used to create a stable and dense alloy. The obtained 3D-printed specimens were characterized to assess the laser power–dependent microstructures, compositions, microhardness, grain sizes, color filling, and dimensional stability in terms of height/width. FESEM micrographs of the obtained alloys revealed the existence of porous spherical grains of mean size in the range of 50–81 μm. The alloy deposited at 300 W and 0.495 mm/s scan speed displayed the maximum hardness (excellent bong strength) value of 859.2 HV0.5 devoid of any crack and porosity. XRD patterns of the alloy revealed the existence of α + β martensitic phase transformation which is responsible for the marginal increase of hardness. It is asserted that the proposed 3D-printed Ti6Al4V alloy can be beneficial for the development of efficient structural parts desired for diverse applications.
... Titaniumbased alloys exhibit low density and exceptional thermal and mechanical resistance [18]. These properties are result of the unique composition and crystal structure of titanium alloys [19], which can be tailored through alloying and heat treatment processes, making them ideal for various aerospace applications [20]. The demand for titanium-based alloys in aerospace continues to grow due to the following reasons: For lightweight construction, titanium alloys have significantly lower density compared to steel and other metals, such as iron and nickel, resulting in lighter aircraft components [21]. ...
This chapter in this book will focus on the mechanical properties, including strength, toughness, and fatigue resistance, of titanium-based alloys and their significance in aerospace applications. It will discuss several types of titanium alloys and explore the unique characteristics of these alloys, such as high strength-to-weight ratio, corrosion resistance, and excellent high-temperature performance. The chapter also will discuss specific challenges and considerations in designing and manufacturing components using titanium-based alloys for aerospace applications, highlighting the benefits and limitations of these materials. Additionally, it will provide case studies and examples of successful applications in the aerospace industry, showcasing the uniqueness and effectiveness of titanium-based alloys in this field.
... Near α titanium alloys have been commonly employed as significant structural materials in aerospace, automotive and military fields due to low density, high specific strength, and excellent resistance to creep deformation [1][2][3][4]. Traditional near α titanium alloys, such as Ti-6Al-2.75Sn-4Zr-0.4Mo-0.45Si (in weight percent wt%) (Ti1100) [5], Ti-5.8Al-4Sn-3.5Zr-0.7 Nb-0.5Mo-0.35Si ...
Hot compression deformation characteristics of TiBw/Ti65 composites for high‑temperature application
... (TA15) composites and attributed the texture formation to the rolling deformation and dynamic recrystallization. Besides, Zhang et al. [40] proposed that Introduction Near α titanium alloys have been commonly employed as significant structural materials in aerospace, automotive and military fields due to low density, high specific strength, and excellent resistance to creep deformation [1][2][3][4]. Traditional near α titanium alloys, such as Ti-6Al-2.75Sn-4Zr-0.4Mo-0.45Si (in weight percent wt%) (Ti1100) [5], Ti-5.8Al-4Sn-3.5Zr-0.7 Nb-0.5Mo-0.35Si ...
Ti–5.9Al–4.0Sn–3.5Zr–0.5Mo–0.3Nb–1.0Ta–0.4Si–0.8W–0.05C (Ti65) alloy is a high-temperature titanium alloy designed for service at 650 °C. To further improve the elevated temperature mechanical performance of Ti65, Ti65-based composites have been fabricated in the present study through a low-energy ball milling and reaction hot-press sintering process. Hot compression tests were further performed on the as-sintered TiB/Ti65 composites at the temperature ranging from 1040 to 1100 °C at the strain rate of 1–0.001 s⁻¹. The results show that during deformation at 1–0.1 s⁻¹, dynamic recrystallization was the dominant mechanism. At the low strain rate of 0.01–0.001 s⁻¹, dynamic recovery became the predominant mechanism. Hyperbolic constitutive equations were calculated and the processing maps were constructed based on dynamic material modeling. The activation energy for hot deformation was determined to be 321.57 kJ/mol and the ideal processing parameters for the network composite were 1070–1100 °C with a strain rate of 1–0.1 s⁻¹. The microstructural analysis of the hot compression-deformed samples revealed the presence of two dynamic recrystallization mechanisms: continuous dynamic recrystallization and discontinuous dynamic recrystallization. After hot compression, metallic matrix exhibited preferred orientation, including a strong <1¯21¯0>\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$< \overline{1}2\overline{1}0 >$$\end{document}//CD fiber texture and <011¯1>\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$< 01\overline{1}1 >$$\end{document}//CD fiber texture. Matrix flow induced TiB whiskers rotation, producing a pronounced [100]\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$[100]$$\end{document}//CD texture and a weak [010]\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$[010]$$\end{document}//RD and [010]\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$[010]$$\end{document}//ND texture.
... The strength of the structure depends on the structure's shape and material. Regarding materials, aluminum and titanium [13] are commonly used in the aerospace and automobile industries due to their high specific strength and stiffness. Moreover, new materials have been researched for automobile [14] and aerospace applications [15][16][17][18], including ceramics [19], composites [20], and nanocomposites [21]. ...
The current study aims to develop a methodology for obtaining topology-optimal structures made of short fiber-reinforced polymers. Each iteration of topology optimization involves two consecutive steps: the first is a simulation of the injection molding process for obtaining the fiber orientation tensor, and the second is a structural analysis with anisotropic material properties. Accounting for the molding process during the internal iterations of topology optimization makes it possible to enhance the weight efficiency of structures—a crucial aspect, especially in aerospace. Anisotropy is considered through the fiber orientation tensor, which is modeled by solving the plastic molding equations for non-Newtonian fluids and then introduced as a variable in the stiffness matrix during the structural analysis. Structural analysis using a linear anisotropic material model was employed within the topology optimization. For verification, a non-linear elasto-plastic material model was used based on an exponential-and-linear hardening law. The evaluation of weight efficiency in structures composed of short-reinforced composite materials using a dimensionless criterion is addressed. Experimental verification was performed to confirm the validity of the developed methodology. The evidence illustrates that considering anisotropy leads to stiffer structures, and structural elements should be oriented in the direction of maximal stiffness. The load-carrying factor is expressed in terms of failure criteria. The presented multidisciplinary methodology can be used to improve the quality of the design of structures made of short fiber-reinforced composites (SFRC), where high stiffness, high strength, and minimum mass are the primary required structural characteristics.
... Titanium alloy Ti-6Al-4V, as a dual-phase alloy, is widely used in aerospace and marine fields as one of the most popular advanced engineering materials, due to its high strength, excellent ductility, and fatigue resistance [1][2][3]. It has been revealed that the scatter of fatigue life is governed by microstructural features [4,5], such as defect morphology and size, grain size, inclusions, microstructural distribution, etc. Dual-phase Ti-6Al-4V alloy can be categorized into equiaxed structure, bimodal structure, and fully lamellar structure from the aspect of microstructure. ...
Microstructural defects and inhomogeneity of titanium alloys fabricated by additive manufacturing technology make their fatigue performance much more complicated, especially reflected in the dispersion of fatigue life. This work employs crystal plasticity finite element method (CPFEM) to predict high cycle fatigue (HCF) life of bi-lamellar Ti-6Al-4V alloy. We first propose a modified VT technique to build representative volume element (RVE) models highlighting lamellar microstructure and micro-defects. Subsequently, fatigue indicator parameter (FIP) is adopted to analyse fatigue deformation under cyclic loading. Finally, HCF life determined by critical fatigue indicator parameter is compared with experimental data collected from published literatures. The results demonstrate that our approach is able to reflect the dispersion of fatigue life and to predict HCF life of bi-lamellar Ti-6Al-4V in a satisfactory manner.
... Titanium (Ti-6Al-4V) alloys are used in various industries such as aerospace [190], automotive [191] and medical [192]. They have describable properties like good mechanical properties [193], high strength-to-weight ratio [194], and excellent corrosion resistance [195]. ...
Metal additive manufacturing (AM) techniques like laser powder bed fusion can print highly complex geometries, ideally with internal sensors. Depending on the component shape these internal sensors, may only be accessible and monitored from the outer surface of the component. Hence, placing or printing of the sensors inside the component requires the sensor to communicate information from outside with remote sensing. Ideally, sensors would be added during printing; however, during LPBF very high temperatures (> 3347℃) are reached causing thermal damage to sensors. Two sets of results are presented. Firstly, four sensors were successfully designed and embedded using two types of novel sensors. An embedding methodology was developed and validated for strain monitoring in Ti-6Al-4V components. A powder protective layer was introduced to prevent damaging the sensors during the laser scanning process. An optimal 1 mm powder protective layer was determined using computational analysis and validated through three-point flexural bench testing. A 1 mm powder protective layer was effective for the strain gauges that were printed using direct ink write (DIW) with glass fibre (GF) reinforced phenolic backing and tripropylene glycol diacrylate (TPGDA) backing. Surface roughness affects the mechanical performance and durability of LPBF components. The surface topology requirements also vary on component application. The evolution mechanisms of surface roughness during LPBF are not well understood due to a lack of in situ characterisation methods. Therefore, the second set of experiment focused on defect dynamics are quantified using synchrotron X-ray imaging and ex situ optical imaging and explain the evolution mechanisms of side-skin and top-skin roughness during multi-layer LPBF of Ti-6Al-4V. Then a surface topology matrix was developed that accurately describes surface features. The results suggest that the proposed process can open new avenues for LPBF technology to realise metal components with a self-cognitive ability using integrated sensors and highlight the need for hybrid smart manufacturing to meet the demands of multiple sectors e.g., biomedical and aerospace.
... The importance of the Ti6Al4V α-β titanium alloy within various industries, including aerospace applications, medical and petrochemical equipment, etc., is widely confirmed [199][200][201][202]. Extensive research and investigation were conducted by numerous researchers on the interaction between hydrogen and CM Ti6Al4V alloys, including HE. ...
Understanding the impact of hydrogen embrittlement (HE) on the mechanical properties of additively manufactured (AM) metals is of utmost importance for industries utilizing these materials, including critical hydrogen transportation and storage applications. This comprehensive review paper explores the effects of HE on AM alloys, emphasizing the crucial role of microstructure and its influence on HE and hydrogen-induced crack initiation (HICI) and propagation processes. Recent studies indicate that the HE in AM metals may deviate from that observed in conventionally manufactured (CM) metals. The unique characteristics of AM processes may introduce additional factors that affect the complex hydrogen-materials interactions and HE. The hydrogen accumulation at phase interfaces and local reaching of the critical hydrogen concentration represents the primary reason for HICI in AM metals. The specific microstructure of AM and interfaces between phases in the microstructure present crucial factors that influence the HE of AM metals. The interface between phases, which serves as a material structure discontinuity and a location for misfit energy within the structure, can play a critical role in the drop of the HE resistance of certain materials (e.g., martensite/austenite interface in stainless steels, ferrite/perlite interface in low carbon steels, α/β interface in titanium alloys, γ′/ γ″ interface in nickel-based
alloys, etc.). Titanium and nickel alloys demonstrate comparable microstructural features concerning HE due to the laminar phase structure that develops during heat treatment and the secondary phase allotropy in both metals. However, stainless steels, such as SS316 and SS304, follow a distinct mechanism where austenite to martensite transformation predominantly governs hydrogen embrittlement. It is noteworthy that the effect of hydrogen embrittlement in additively manufactured metals seems to be less pronounced compared to CM metals. A comprehensive investigation of HE mechanisms and their interaction with microstructure according to the HELP + HEDE model can provide valuable insights into the susceptibility of AM metals to HE and HICI. This review underscores the need for continued investigation to ensure the reliable performance of AM metal components exposed to hydrogen and HE in various industrial applications. Also, it provides an in-depth understanding of hydrogen embrittlement in AM metals, providing recommendations for the design, development, and safety introduction of new additively manufactured alloys in hydrogen-based energy solutions. Finally, a
perspective on future necessary experiments for exploring the influence of porosity in AM metals on HE, hydrogen-induced crack initiation, and other hydrogen damage mechanisms, including its interaction with microstructure, is given.
... The properties of the base material E and ν (Young modulus and Poisson ratio) correspond to the Ti-6Al-4V base material used as a substrate material in its powder form. This alloy and its variants are widely used in a wide range of aerospace, industrial and biomedical applications, among others, for their numerous features, such as high corrosion resistance, light weight and high strength [121][122][123]. Each cell is characterized by an ideal fraction solid denoted with the symbol s. ...
Additively printed mechanical metamaterial structures optimize material, energy and waste, producing more sustainable products. Their introduction in the production workflow depends on having proper tools for accurately predicting their performance. However, the additive manufacturing process incorporates significant defects which result in an important change of the effective properties of the metamaterial cell. Finite element predictions using perfect geometries and nominal base material properties result in important errors which may require excessive uncertainty-related safety design margins. This work presents a methodology to introduce the effect of the most common defects in finite element models to compute the effective mechanical response of different metamaterials printed by Selective Laser Melting. It is shown that even at elastic infinitesimal strains, the defects produce an important change in the effective mechanical capabilities of the metamaterial, which also depend on the type of the metamaterial cell studied and on the type and magnitude of defects. With the proposed methodology, which incorporates the distribution of defects in the finite element model, the predicted mechanical properties of the metamaterial better match the experimental ones. It is shown that the initial discrepancies in the order of 100% are reduced to an order of 5%.
... Titanium and its alloys are crucial resources in aerospace and biomedical materials due to their light weight, superior mechanical properties, and biocompatibility [1][2][3]. Besides conventional applications, new functionalities are enabled at the nanoscale, including catalytic activity [4], superplasticity [5], and hydrogen storage capacity [6]. ...
Nanoscale metallic titanium (Ti) offers unique energetic and biocompatible characteristics for the aerospace and biomedical industries. A rapid and sustainable method to form purified Ti nanocrystals is still in demand due to their high oxygen affinity. Herein, we report the production of highly purified Ti nanoparticles with a nonequilibrium face center cubic (FCC) structure from titanium tetrachloride (TiCl4) via a capacitively coupled plasma (CCP) route. Furthermore, we demonstrate a secondary H2 treatment plasma as an effective strategy to improve the air stability of a thin layer of nanoparticles by further removal of chlorine from the particle surface. Hexagonal and cubic-shaped Ti nanocrystals of high purity were maintained in the air after the secondary H2 plasma treatment. The FCC phase potentially originates from small-sized grains in the initial stage of nucleation inside the plasma environment, which is revealed by a size evolution study with variations of plasma power input.
... Metal alloys have been instrumental throughout world history, with their significance dating from the historical period known as the Bronze Age. In the modern era, these alloys assume critical roles in diverse applications within automotive and aerospace engineering industries [11], as well as serving as fundamental materials in nuclear and biomedical contexts [12]. High entropy alloys (HEAs), commonly known as Multi-Principal Element Alloys (MPEAs), are alloys characterized by the inclusion of a minimum of five principal elements. ...
High entropy alloys (HEAs) are distinguished by their enhanced physicochemical properties, attributed to the formation of various phases such as solid solution (SS), intermetallic (IM), or a combination (SS + IM). These phases contribute distinctively to the microstructure of the alloys. A critical aspect of alloy design revolves around accurately predicting these phases, which has led to the integration of sophisticated data vetting methods and Machine Learning (ML) algorithms in recent research. This review paper aims to provide a comprehensive analysis of the advancements in phase prediction accuracy within HEAs, an essential component in the development of these alloys. HEAs are known for their intricate compositions, offering a wide spectrum of material properties, making them particularly relevant for applications aimed at future sustainability. Phase engineering in HEAs unlocks the potential for creating materials tailored to eco-friendly technologies and energy-efficient solutions. The challenge in predicting phase selection in HEAs is accentuated by the limited data available on these complex materials. This review delves into how advanced data vetting techniques and ML algorithms are being employed to overcome these challenges, thus contributing significantly to sustainable material design. The paper examines various algorithms used in HEA phase prediction, including KNN (K-Nearest Neighbors), SVM (Support Vector Machines), ANN (Artificial Neural Networks), GNB (Gaussian Naive Bayes), and RF (Random Forest). It discusses the testing accuracy of these algorithms in classifying HEA phases, revealing variations in their effectiveness. The review highlights the superior accuracy of ANNs, followed closely by KNN and SVM, while noting the comparatively lower accuracy of GNB. This comprehensive review synthesizes current research efforts in utilizing computational methods to design HEAs, underlining their broader implications in expediting the discovery and development of diverse metal alloys. These efforts are pivotal in meeting the evolving demands of modern engineering applications, thereby contributing to the advancement of materials science.
... Titanium and its alloys are utilized extensively in various industries due to their unique traits, such as their low modulus of elasticity, elevated strength-to-weight ratio, great biocompatibility, and corrosion resistance [1]. Titanium alloys are popular as implant materials for orthopedic and dental applications due to their favorable mechanical properties and biocompatibility [2,3]. Surface properties like chemical composition and topography influence this biocompatibility. ...
Titanium and its alloys have numerous biomedical applications thanks to the composition and morphology of their oxide film. In this study, the colorful oxide films were formed by anodizing cast Ti-6Al-4V and Ti-6Al-7Nb alloys in a 10% oxalic acid solution for 30 s at different voltages (20-80 V) of a direct current power supply. Atomic force microscopy was used as an accurate tool to measure the surface roughness of thin films on the nanometer scale. Scanning electron microscopy and X-ray diffraction were performed to analyze surface morphology and phase structure. According to the results, the produced titanium oxide layer showed high surface roughness, which increased with increasing anodizing voltage. The impact of anodizing voltages on the color and roughness of anodized layers was surveyed. The corrosion resistance of the anodized samples was studied in simulated body fluid at pH 7.4 and a temperature of 37 °C utilizing electroche-mical impedance spectroscopy and the potentiodynamic polarization method. The anodized samples for both alloys at 40 V were at the optimal voltage, leading to a TiO 2 layer formation with the best compromise between oxide thickness and corrosion resistance. Also, findings showed that TiO 2 films produced on Ti-6Al-7Nb alloys had superior surface roughness properties compared to those of Ti-6Al-4V alloys, making them more appropriate for orthopedic applications. From the obtained data and the fruitful discussion, it was found that the utilized procedure is simple, low-cost, and repeatable. Therefore, anodization in 10% oxalic acid proved a viable alternative for the surface finishing of titanium alloys for biomedical applications.
dual phase Ti-(0~6 wt.%) Fe alloys were prepared via sintering and hot rolling process to clarify the effects of Fe contents and the rolling temperature on their microstructures and crystalline orientation. With an increase in the Fe content, the volumetric fraction of the β-Ti phase, contains high Fe solutes, drastically increased. When hot rolled at 750°C (α+β dual-phase temperature), each phase grew immediately after rolling and suppressed each other’s grain growth, resulting in fine microstructure formation and uniform residual strain. In Ti-Fe alloys rolled at 1000°C (single β-phase temperature), a very small amount of residual strain was observed, and acicular α-Ti grains with random crystalline orientations were formed due to the phase transformation from β-Ti grains after rolling.
Micromechanical characterization of the oxygen-rich layer (ORL) of a Ti-6Al-4V alloy due to high-temperature oxidation was investigated at room temperature. The tensile strength of the pre-oxidized specimens linearly decreased as a function of the surface fraction of ORL in relation to the gage section, demonstrating a competition between oxygen strengthening and embrittlement. Electron-probe microanalyses and nanoindentation testing aimed at locally assessing the elastic and hardness response of the material as a function of the oxygen content. These properties were used in finite element simulations to quantify stress profiles within the oxygen-graded material for different ORL thickness/specimen thickness couples.
This investigation aims to analyze the impact of scanning direction, scanning speed, and power level (%) on the surface roughness of Ti-6Al-7Nb alloy specimens subjected to laser micro-engraving. The laser micro-engraving process was carried out by scanning the predetermined geometric configuration six times. Factorial analysis was implemented to determine the impact of system parameters on the surface roughness. Throughout the micro-engraving operations, line spacing, frequency, and pulse width parameters were maintained at a consistent value of 0.03 mm, 100 kHz, and 300 ns, respectively. The optimal conditions for achieving the lowest surface roughness were observed at a scanning speed of 700 mm/s, a power level of 60%, and a scanning direction of 90°. Moreover, in accordance with the experimental parameters employed in this investigation, it was observed that increasing the scanning speed while maintaining a constant power level (%) reduced surface roughness. There was a direct correlation between the increase in power level (%) and a corresponding increase in surface roughness.
The effect of surface modification by oxygen and nitrogen from a controlled gaseous medium on the fatigue life under cyclic and long-term static loading of Zr-1%Nb alloy thin-sheet samples was studied. Positive effect of gas nitriding and thermal oxidation on mechanical and fatigue performance under cyclic and static loading of Zr-1%Nb alloy was shown: under pure bending – by ~23%; under cyclic stretching – by ~25% and under long-term static loading in air with exposure of 100 h at room temperature – by ~12% and at a temperature of 380 °С by ~6%. It was established that oxidation and nitriding effectively improve fatigue life and fracture stresses under long-term static loading of Zr-1%Nb alloy thin-sheet.
Manufacture of intricate components, products without the need for tooling, shorter lead times and material grading are the most beneficial applications of Additive Manufacturing (AM). The goal of this study is to develop a design optimization framework for developing an aircraft component using additive manufacturing utilizing topology and lattice optimization techniques. Solid works were used to create a 3D model of an aircraft bracket made of Titanium alloy. To minimize mass and maximize frequency and stiffness, the optimization was performed using Altair Inspire 2022.1 software. Component optimization was performed using the finite element method, which entails reducing material while maintaining the proper function of the modelled component. The optimal performance of the designed aerospace component using topology with lattice infill is achieved with minimization of mass from 2.24810 kg to 0.16235 kg and the volume from 5.07579x10⁵ mm³ to 4.70922x10² mm³, frequency is increased from 0.02 kHz to 13.9537 kHz, stiffness is maximized from 1,485,884.1 N/m to 4,558,924.0939 N/m with a factor of safety of 1.73. Therefore, the mechanical properties of the optimized model can full fill its overall performance.
Investigating fatigue failure in titanium alloys is crucial for material design and engineering. Fatigue behavior in dual‐phase titanium alloys is strongly correlated with microstructural features and microdefects. This work formulates an improved modeling method to investigate fatigue behavior of bimodal Ti–6Al–4V, emphasizing the effects of lamellar orientation and microdefects. Using an improved Voronoi tessellation method, we establish representative volume element (RVE) models with various grain size distributions. Crystal plasticity finite element modeling (CPFEM) is used to analyze fatigue deformation in bimodal Ti–6Al–4V, considering microdefects and lamellar orientation. Fatigue indicator parameters are then incorporated into CPFEM to predict fatigue life and verified with experimental data. Numerical results highlight the significant influence of lamellar orientation and microdefects on fatigue behavior, with predicted life within the 3‐error band. This method efficiently overcomes challenges in quantitatively characterizing microstructural lamellae that experiments are short of, paving the way for designing fatigue‐resistant alloy materials with similar microstructures.
Direct joining of titanium and stainless steel 316 L with a strong interface is very challenging due to the formation of the brittle intermetallic compounds FeTi and Fe2Ti in the intermixing zones and to the high residual stress induced by the mismatch of the thermal expansion coefficients. In this bimetallic directed energy deposition study, firstly, deposition of Ti on stainless steel was carried out using conventional process parameter regime to understand the interfacial cracking susceptibility and then a novel high powder flowrate approach is proposed for controlling the dilution and constraining the intermetallic phases forming at the interface. The influence of high temperature substrate preheating (520 °C) on the cracking susceptibility and interface strength was also investigated. The deposited Ti samples and their interfaces with the 316 L substrate were characterized with optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy to investigate the geometry, microstructures and chemical compositions in relation to the cracks. The high powder flowrate deposition of Ti on stainless steel 316 L results in an extremely thin dilution region (~ 10 μm melt pool depth in the substrate) restricting the formation of the intermetallic phases and cracks. The ultimate shear strength of the interfaces of the crack free sample was measured from cuboid deposits and the highest measured strength is 381 ± 24 MPa, exceeding the weaker base material pure Ti. The high interfacial strength for high powder flowrate deposition is due to the substantial attenuation and shadowing of the laser beam by the in-flight powder stream as demonstrated by the high-speed imaging resulting in an extremely small dilution region.
Gas-atomization is extensively used to produce metallic feedstock powders for additive manufacturing processes, including gas dynamic cold spray processing. This work explores the potential utility of on-demand recycled titanium scrap feedstock powder as a viable substitute for virgin powder sources. Three recycled titanium powders were atomized from different battlefield scrap sources using a mobile foundry developed by MolyWorks Materials Corporation. Recycled titanium alloy powders were compared against virgin Ti-6Al-4V powder to verify there were no significant variations between the recycled and virgin materials. Powder characterization methods included chemical analysis, particle size distribution analysis, scanning electron microscopy (SEM), Karl Fischer (KF) titration moisture content analysis, X-ray diffraction (XRD) phase analysis, microparticle compression testing (MCT), and nanoindentation. Results indicate that recycled titanium powder provides a viable alternative to virgin titanium alloy powders without compromising mechanical capabilities, microstructural features, or ASTM-specified composition and impurity standards. The results of this work will be used to aid future research efforts that will focus on optimizing cold spray parameters to maximize coating density, mechanical strength, and hardness of recycled titanium feedstock powders. “Cold spray” presents opportunities to enhance the sustainability of titanium component production through the utilization of recycled feedstock powder, mitigating issues of long lead times and high waste associated with the use of conventional virgin feedstock.
Mechanical alloying (MA) creates advanced Mg-Ti alloys via controlled microstructural changes and uniform elemental distribution. High-energy ball milling induces solid-state reactions, refining alloys. Parameters like duration, ball-to-powder ratio, and speed impact microstructure. Analytical tools reveal phase changes, microstructural evolution, and element distribution. Mg-Ti alloys exhibit enhanced mechanical properties. MA shows promise for aerospace and automotive applications, with challenges to address for full potential realization. This chapter discusses the different approaches opted for mechanical alloying of magnesium and titanium alloys.
Ti alloys are used in a variety of high-performance applications. Properties that lead to the selection of Ti alloys include modulus, chemical inertness, density, static strength, fatigue strength and damage tolerance (fracture toughness and fatigue crack growth). The reasons that Ti alloys are selected for a wide range of products have been widely discussed. Reasons for not selecting Ti alloys have been less widely discussed, and are the focus of this paper. This paper describes examples where alternate materials have been chosen in lieu of Ti alloys. The reason for these choices include elevated temperature creep strength, the tendency for combustion, raw material cost and article manufacturing cost. Specific examples of aircraft engine and aircraft components will be described and the reasoning behind the selection of alternate materials will be outlined. The paper concludes by suggesting factors that could re-balance the decision making process in favor of Ti alloys.
The alloy system based on the nominal composition Ti–25AI was first studied over 30 years ago, and has undergone research for approximately the past 15 years. However, only during the past 6 years has this system been open for general public disclosure of previous government research in this area, this has lead to a deluge of research results across the world. This review covers those results as they pertain to the α2 alloy system based on Ti–AI–Nb. The complicated phase transformation sequences and stabilities for this alloy system are addressed. Furthermore, dislocation behaviour in both single phase α2 and dual phase α2 β/B2 is described. Finally, the correlation of microstructure and dislocation behaviour with tensile and fracture properties is presented.
The object of this paper is to describe a coordinated research and development program which has been pursued by an Air Force-Industry-University team for more than twelve years. The focus of our attention has been on the development, processing, and engine testing of alloys based on intermetallic compounds, specifically on the aluminides of titanium, iron, and nickel. The titanium aluminides, Ti3Al and TiAl, are the materials with which we have been working the longest and on which development has proceeded the furthest. This Symposium has provided the first opportunity to review the progress of the titanium aluminide development programs sponsored by the Air Force and some of the engine testing efforts undertaken by the engine manufacturers.
Development and processing of high-temperature materials is the key to technological advancements in engineering areas where materials have to meet extreme requirements. Examples for such areas are the aerospace and spacecraft industry or the automotive industry. New structural materials have to be “stronger, stiffer, hotter, and lighter” to withstand the extremely demanding conditions in the next generation of aircraft engines, space vehicles, and automotive engines. Intermetallic γ-TiAl-based alloys show a great potential to fulfill these demands.
Intermetallic titanium aluminides offer an attractive combination of low density and good oxidation and ignition resistance with unique mechanical properties. These involve high strength and elastic stiffness with excellent high temperature retention. Thus, they are one of the few classes of emerging materials that have the potential to be used in demanding high-temperature structural applications whenever specific strength and stiffness are of major concern. However, in order to effectively replace the heavier nickel-base superalloys currently in use, titanium aluminides must combine a wide range of mechanical property capabilities. Advanced alloy designs are tailored for strength, toughness, creep resistance, and environmental stability. These concerns are addressed in the present paper through global commentary on the physical metallurgy and associated processing technologies of γ-TiAl-base alloys. Particular emphasis is paid on recent developments of TiAl alloys with enhanced high-temperature capability.
Emerging metallic materials, processing, and manufacturing technologies offer an important opportunity to meet current aircraft-airframe
and jet-engine affordability goals, due to their inherent low material costs and excellent producibility characteristics.
But to successfully meet systems goals within this new affordability-driven scenario, a consolidation ofindustry and military-agency
development resources and technology-implementation activities is necessary to positively impact the military-aircraft production
and sustainment infrastructure. To address this need, a consortium of aircraft and engine manufacturers and key material-and
engine manufacturers and key material-and component-supplier companies has been formed to identify critical affordable metal
technologies, develop a strategic roadmap for accelerated development and insertion of these technologies, and oversee execution
of development activities by integrated industry teams. the goal of the Metals Affordability Initiative is to reduce the cost
of metallic components by 50 percent while accelerating the implementation time.
Titanium aluminides based on TiAl and Ti3Al are emerging as a revolutionary high temperature material. In order to confer these materials the thermomechanical properties required for industrial applications, two-phase alloys are developed by microalloying. That leads to formulate different alloy compositions adapted to the fabrication process and to the specific properties required for engineering applications. Knowledge of the fundamental understanding such as composition–structure–mechanical property relationships, microalloying effects and temperature dependence of plasticity micromechanisms are in progress and are used to optimise mechanical properties such as yield and creep strengths, tensile ductility and fracture resistance. Cast processing of XD™ near-γ titanium aluminides has been successfully developed to manufacture near-net shaped components. For wrought alloys, investigation is aimed at producing large homogenised ingots and at improving the balance of properties by thermomechanical processing and heat treatments. Microstructure control is attempted by examining the role of solidification paths, phase relations and transformations and microalloying effects. The research efforts directed towards achieving balanced engineering properties are reviewed.
Titanium and titanium alloys are excellent candidates for aerospace applications owing to their high strength to weight ratio and excellent corrosion resistance. Titanium usage is, however, strongly limited by its higher cost relative to competing materials, primarily aluminum alloys and steels. Hence the advantages of using titanium must be balanced against this added cost. The titanium alloys used for aerospace applications, some of the characteristics of these alloys, the rationale for utilizing them, and some specific applications of different types of actual usage, and constraints, are discussed as an expansion of previous reviews of β alloy applications. [1,2]
This status report focuses on specific products of two γ-TiAl alloys that are advancing toward structural applications for 550–750°C service in advanced turbine engines. These are low-pressure turbine blade, transition-duct beam and radial diffuser castings for engine components, and corner-beam and closeout beam castings for the outlet-nozzle of a very large engine. Also included are current development of sheet corrugations for formed subcomponents and the perfection of cast turbine wheels for automotive turbochargers. In the current implementation stage, alloy composition, desired process and component definition are the important introductory issues. Then, the engineering technology that must be developed is discussed for the desired final product and a match of cost and benefit. Balancing better performance with the acceptance constraints is the key. Cost is a major constraint along with real and perceived risk. Within five to ten years, systematic reduction of certain hardware costs will occur as familiarity builds and enters into the production stage.
Seagle inTitanium ’99: Science and Technology CRISM “Prometey” St
- D Eylon
Guedou inTitanium ’99: Science and Technology CRISM “Prometey” St
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Paton inTitanium ’99: Science and Technology CRISM “Prometey” St
- R R Boyer
- J C Williams