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Publications (245)
In this work, the microstructure and texture of Mg-1.0Al-xZn-0.2Mn-0.5Ca (wt.%, x = 0, 1) alloys, which were produced via conventional casting or twin roll casting (TRC), were investigated, and their relation to the mechanical properties of the sheets at the final gage was analyzed. In the Zn-containing AZMX1100 alloy sheets, the amount and size of...
In this work, we investigated the enhancement of corrosion resistance in a biodegradable Mg-0.7Zn-0.6Ca (wt. %) alloy (MgZnCa) by applying ZrO2 thin films deposited via reactive magnetron sputtering. We employed a fractional factorial experimental design to systematically examine the influence of the deposition power, deposition time, and O2 fracti...
This paper investigates the influence of addition of Ca in a Y-Zn-containing magnesium alloy on the dynamic and static recrystallization behaviors and reveals the formation mechanism of the quadrupole texture during thermomechanical processing. Direct extrusion of flat bands has been conducted at various process conditions to study the difference b...
The present work investigates the influence of two different processing routes on mechanical behavior of Mg-Zn-Nd-Y-Zr (ZEWK2000) Mg sheets. Hot-rolled sheets, with dimensions of 200 × 200 × 1.8 mm3, were processed at 225 ℃ by a two equal channel angular pressing (ECAP) passes following the route DC2 with a rotation of 90° around the normal directi...
Due to their high specific strength, rolled Magnesium sheets have excellent prerequisites for lightweight construction applications. However, the hexagonal crystal structure of Mg offers only few slip systems that can be activated at low temperature, thus limiting the ductility. Additionally, the pronounced texture of rolled Mg sheets further limit...
An understanding of deformation behavior and texture development is crucial for the formability improvement of Mg alloys. X-ray line profile analysis using the convolutional multiple whole profile (CMWP) fitting method allows the experimental determination of dislocation densities separately for different Burgers vectors up to a high deformation de...
This study examined the microstructure evolution during the thermomechanical treatments of the twin roll cast strip of magnesium alloy. Magnesium alloy composed of 0.6 wt% Zn and 0.6 wt% Ca was manufactured by TRC and subsequently rolled at 370 °C, and the rolled sheets were heat treated at 400 °C for various periods of time. In the as-TRC plate, t...
Plastic instability, called Portevin-Le-Chatelier (PLC) effect, manifests itself as an unstable plastic flow during tensile tests of structural materials. This phenomenon has a strong influence on diverse properties, leading to unexpected vulnerabilities in the service environment. Among various magnesium-based alloys, PLC phenomenon is most promin...
This paper will give an overview about the development of a material system, which consists of a novel formable magnesium alloy that is provided with an effective corrosion protection coating. The corrosion protection is to be realized in the form of a forming stable powder coating, which can be applied in the coil coating process. To improve the t...
Microstructure, crystallographic texture and age hardenability of the non-flammable Mg-Al-Zn-Ca-Y alloy sheets were investigated as a systematic compositional change. By reducing the Al content to 1 wt.%, fine and homogeneous microstructure was preserved even after the solution-treatment at 500°C, while a weaken texture was obtained. The high Zn/Y...
The application of magnesium flat products is affected by the limited formability at room temperature and the anisotropy of the mechanical properties. The main reason for this is the underlying hexagonal crystal structure of magnesium and the development of strong crystallographic textures during massive forming processes with distinct alignment of...
The microstructural characteristics of biodegradable Mg alloys determine their performance and appropriateness for orthopedic fixation applications. In this work, the effect of the annealing treatment of a Mg-0.7Zn-0.6Ca (ZX11) alloy on the mechanical integrity, corrosive behavior, and biocompatibility-osteoinduction was studied considering two ann...
In the present study, the influence of Zn or Al addition as a third alloying element on the deformation mechanisms of Mg–Nd-based alloys was investigated by quasi in situ tensile tests. Distinct mechanical behaviors were observed between Mg–1.0 Zn–1.7 Nd (ZN12, in wt.%) and Mg–1.0 Al–1.7 Nd (AN12) alloys. The ZN12 alloy showed a lower yield strengt...
Phosphate and silane containing organic self–assembled (SA) layers serve as pre–treatments on magnesium alloy sheet materials. A reliable protection was achieved in this work via application of alkyd–based coatings on the pretreated surface. The idea of adopting SA pre–treatments as functional layers at metal–polymer interface is to influence the a...
Transport is a major contributor to CO2 emissions and is considered the most urgent global climate problem [...]
This work investigates the deformation mechanisms active during high temperature plane strain compression and their impact on the microstructural and texture evolution of an Mg-Zn-Ca-Zr (ZXK) alloy. The microstructures of samples deformed at different strains and different loading directions were examined using electron backscatter diffraction meas...
Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics; nevertheless, its fast degradation rate at the initial stage after implantation remains as one of the main challenges to be resolved. ZrO2-based coatings to reduce the degradation rate of the Mg-implants are an attractive solution since t...
Even though Mg alloys containing Mn and rare earth elements lead to higher ductility and lower yield asymmetry due to the weak texture after extrusion, plastic instability, commonly known as the Portevin–Le Chatelier (PLC) effect, causes unexpected fragility in the service environment. In the present study, the PLC phenomenon and texture developmen...
Ureteral stents are a relatively new potential application for biodegradable Mg alloys. In this study, the corrosion behavior of Mg-1Zn wires and pure Mg wires in artificial urine solution (AUS) is investigated. It is found that AUS possesses a strong pH buffer effect. Hydrogen evolution measurement cannot be used for Mg corrosion test in this AUS...
Magnesium alloys usually exhibit excellent superplasticity at high temperature. However, many Mg alloys have poor formation ability near room temperature. Therefore, preparation of Mg alloys with suitable microstructures to show low or intermediate temperature superplasticity is an important goal. In this work, the superplastic behavior at intermed...
In this work, the influence of twin-roll casting (TRC) speed on the microstructure of the through-thickness uniformity, centerline segregation, and surface quality of three wrought Mg alloys was investigated. The microstructural features of the AZ31, ZX11, and ZWK200 alloys produced at TRC speeds ranging from 1.8 m/min to 2.2 m/min (for the AZ31 an...
The effect of Al content on the texture evolution and recrystallization behavior of the non-flammable Mg sheet alloys containing Ca and Y was investigated in this study. With a decrease in the Al content from 3 wt.% to 1 wt.%, the amounts of the other alloying elements dissolved in the matrix, especially Ca, are increased. The increase of the alloy...
Texture modification during sheet rolling appears differently in binary Mg-RE (rare-earth) or MgCa alloy, compared to their ternary counterparts containing Zn. The differences in texture development and the active deformation mechanisms under tensile loading were investigated in the binary alloys. These analyses are based on in-situ synchrotron exp...
The effect of Ag in solid solution on the microstructure, texture and the deformation behaviour of indirectly extruded Mg was investigated. Ag as a solid solution strengthener affects the behaviour during extrusion, resulting in enhanced deformation related heating and corresponding coarser grained microstructures. No substantial effect on the text...
Age-hardenability and corresponding improvement of the mechanical properties of Mg–1Al–0.7Ca and Mg–1Al–0.7Ca–0.7Y alloy sheets are addressed with respect to the microstructure and texture evolution during thermomechanical treatments. A fine grain structure and weak texture with the basal pole split into the sheet transverse direction are retained...
Wires of magnesium alloys possess a high potential, e.g., as filler materials, for joining applications but also for biodegradable applications, such as suture materials. While the typical process of producing wires is based on a wire drawing process, direct extrusion by using adjusted dies to deal with high degrees of deformation allows a one-step...
Biodegradable Mg-based alloys have attracted increasing attention from orthopedic surgeons and biomaterials scientists since their Young’s modulus is close to that of bone. However, control of the degradation rate is still a challenge. Sputtered TiO2 coatings were deposited on Mg-Zn-Ca alloys aiming to reduce the initial strong reactivity of Mg wit...
Process - property relationship control during magnesium sheet manufacturing is demanding due to the complexity of involved physical parameters and the sensitivity of the system to small changes.
Here, data science might help to extract crucial information on interdependencies between processing parameters and sheet quality. In this paper we sugges...
The present study examines the influence of Ca or Nd on the microstructure and texture modification during indirect extrusion and after subsequent annealing of Mg-Zn based alloys. The addition of such elements influence the recrystallization processes, i.e. dynamic (DRX) and static recrystallization (SRX), and leads to distinctive texture changes o...
Self-assembled (SA) layers of phosphates/silanes/thiols were applied as temporary protective films on Mg-AZ31. Retention of phosphoryl oxygen (P=O) on magnesium (Mg), demonstrates dominant bidentate bonding. Distribution of the phosphate nodules are homogeneous, while silanes form island/cluster depositions, apparently sealing the pores and stabili...
Scientific understanding of the behavior of wrought magnesium alloys is quite mature, with literally thousands of papers published on the topic, along with several reviews. Most of this research is relatively recent, being published after the year 2000. With such a large body of work available to the reader, it could easily be missed that the field...
Three magnesium alloys with texture and microstructure modifying elements, binary M2, and the alloyed counterparts with Ca (MX21) and rare earth element (ME21) were extruded to flat bands under similar conditions. The microstructure and texture in extrusion significantly differ from those developed in rolled magnesium sheets. The influence on the m...
Magnesium alloys attract attention as degradable implant materials due to their adjustable corrosion properties and biocompatibility. In the last few decades, especially wrought magnesium alloys with enhanced mechanical properties have been developed, with the main aim of increasing ductility and formability. Alloying and processing studies allowed...
The influence of rolling and annealing on the resulting mechanical properties and forming behavior of Mg-Zn-RE and Mg-Zn-Ca alloys produced via twin roll casting is investigated. After hot rolling followed by an annealing treatment, both alloys develop a fine-grained microstructure with average grain sizes <10 μm. A distinctive development of a tex...
The development of microstructure and texture during flat product extrusion of magnesium alloys differs significantly from those of rolled sheets. It has especially been shown that the range of microstructures and textures is broad in the case of extrusion which allows significant variations of the resulting textures. Three wrought magnesium-zinc a...
Mg-AZ31 is the typical commercial alloy manufactured in metal sheet form for the automobile and aerospace industry. Twin roll casting (TRC) is the metal processing technique used to produce feedstock materials, which are later subjected to consecutive rolling to sheets at above 250 – 350 °C. Highly reactive nature of magnesium promotes the surface...
Corrigendum to “Influence of Nd or Ca addition on the dislocation activity
and texture changes of Mg–Zn alloy sheets under uniaxial tensile loading”
[Mater. Sci. Eng.: A 761 (22 July 2019) 138053]
Considering the excellent biocompatibility of magnesium (Mg) alloys and their better mechanical properties compared to polymer materials, a wrought MgZnCa alloy with low contents of Zn (0.7 wt%) and Ca (0.6 wt%) (ZX11) was developed by twin roll casting (TRC) technology as potential biodegradable bone plates. The degradability and cell response of...
The microstructure and texture evolution during static recrystallization of Mg-Nd alloys were investigated. Depending on the third alloying element added into Mg-Nd alloy, either Al or Zn, diverse textures are formed during recrystallization annealing. The rolled Mg-2Nd-1Zn sheet shows a high activity of prismatic slip and the formation of a weak t...
In situ hard X-ray diffraction experiments were carried out to investigate the dislocation slip activity of Mg-1 wt.% Zn-based alloys containing Nd or Ca during tensile loading. Diffraction patterns collected during tensile loading at 3 temperatures were analyzed using a convolutional multiple whole profile fitting procedure. High activation of non...
The microstructure-texture evolution of twin-roll-cast strips of an Mg-Zn-Ca-Zr alloy subjected to hot rolling and recrystallization annealing was investigated. Upon annealing, a distinctive change in the main texture components is observed from basal poles tilted towards the rolling direction (RD) to basal poles tilted towards the transverse direc...
The present paper reports an effect of ECAP on the microstructure of the AZ31 magnesium alloy prepared in two conditions: conventionally cast and twin-roll cast. Subsequently, the thermal stability of fine-grained conditions was investigated with a special regard to microhardness, grain structure and dislocation density changes. Similar processing...
The application of Mg–Ag alloys is suggested as biodegradable implant materials in the form of sheets with controllable mechanical properties and appropriate degradation behavior. This study aimed on the understanding of influence of rolling temperature and silver content (2–8 wt %)on the microstructure development, mechanical properties and the de...
The shaping of steel and aluminium sheet with single point incremental forming (SPIF) is well investigated in research context. Specific develop-ments of the tooling and processing technology were realized to transfer the technology to hard-to-form materials, e. g. lightweight construction and composite materials. The forming of the listed material...
Pre‐straining of magnesium alloy modifies the final texture of the material and therefore leads to a different deformation behavior during subsequent loading. At the same time, heat treatment in the context of thermo‐mechanical procedures is used as softening mechanism, as well as for age hardening processing. In mechanical conditions with twin‐dom...
The influence of rolling temperature and pass reduction degree on microstructure and texture evolution was investigated using an AZXW3100 alloy, Mg-3Al-1Zn-0.5Ca-0.5Y, in wt.%. The change in the rolling schedule had a significant influence on the resulting texture and microstructure from the rolling and subsequent annealing. A relatively strong bas...
The present work investigates the influence of shear deformation on microstructural-texture and mechanical behavior of ZEW200 Mg alloy sheets. For the introduction of extra shear deformation during thermomechanical processing, the separate effect of differential speed rolling (DSR) and equal channel angular pressing (ECAP) were analyzed. The result...
Two main impediments are currenty discussed with respect to the industrial application of magnesium sheets. First, the low formability of magnesium sheets requires many rolling passes to roll cast slabs to final gauge, which leads, second, to high costs for the production of magnesium sheets. An alternative cost-saving process chain for magnesium s...
A three-dimensional approach to microstructural investigations was for the first time applied to a continuous cast material in order to understand solidification processes and liquid flow during casting. A twin-roll cast AZ31 magnesium alloy strip was subjected to observations by light optical microscopy, electron microscopy, and X-ray microtomogra...
Different production processes like casting and twin roll casting of Mg-based alloys have a significant influence on the microstructure and texture of the resulting feedstock material for the subsequent rolling process. This leads to improved mechanical properties in the final sheets produced by twin roll casting. In this paper the processing of an...
A three-dimensional approach to microstructural investigations was for the first time applied to a continuous cast material in order to understand solidification processes and liquid flow during casting. A twin-roll cast AZ31 magnesium alloy strip was subjected to observations by light optical microscopy, electron microscopy, and X-ray microtomogra...
The influence of thermomechanical processing on the microstructure and texture evolution is examined in the present study using an AZ31 alloy modified by Ca and Y addition. AZXW3100 alloy sheets were produced by hot rolling at two different temperatures of 450◦C and 500◦C. Changes in the deformation degree per pass at each rolling temperature were...
Magnesium alloys with rare earth or Ca additions often form weak textures during rolling of magnesium sheets or extrusion of round bars. However, in the case of the extrusion of flat profiles of such alloys strong textures may develop. This is of fundamental importance because weaker textures are associated with higher ductility or formability. Var...
The invention refers to a method of manufacturing a sheet metal product (28) including the steps of: a) providing a molten magnesium alloy (10, 10') consisting of - 0.4 wt% to 2 wt% Zn, - 0.4 wt% to 1 wt% Ca, - 0.00 wt% to 1.0 wt% rare earth elements and/or Sr, - unavoidable impurities and - the balance being Mg b) forming a strip (10, 10") in a tw...
The texture weakening is an effective way to improve the mechanical properties and the formability of wrought Mg alloys. The addition of rare earth elements (RE) into Mg alloys leads to a texture weakening during thermomechanical processes with a less distinct alignment of basal planes parallel to the main deformation axis. Understanding the role o...
The texture weakening is an effective way to improve the mechanical properties and the formability of wrought Mg alloys. The addition of rare earth elements (RE) into Mg alloys leads to a texture weakening during thermomechanical processes with a less distinct alignment of basal planes parallel to the main deformation axis. Understanding the role o...
Thermomechanical treatment consisting of pre-compression and a subsequent isothermal aging was used to improve the compressive properties of extruded Mg-Zn-Ca (ZX10) alloy. Isothermal aging at 150 °C and 200 °C was performed on as-extruded samples for various times to find peak aged conditions. To achieve a different twin volume fraction in the all...
Due to their excellent strength-to-weight ratio, Mg alloys are attractive for applications where weight savings are critical. However, the limited cold formability of wrought Mg alloys severely restricts their widespread usage. In order to study the role that deformation twinning might play in limiting the elongation-to-failure, in-situ tensile tes...
As a generalized semi-finished product, the use of magnesium sheets requires addressing two major aspects of their processing: their microstructure and texture control, which are both essential for the forming behavior of such sheets during their forming to parts. Further, the processing of such sheets is complex, and therefore expensive, and requi...
We examined the microstructure and texture evolution during the recrystallization annealing of cold rolled Mg-1Y and Mg-0.2Zn-1Y alloys. At the early annealing stage, new grains are nucleated on sub-units with 200–300 nm surrounded by dislocation walls within shear bands. The Zn and Y addition reduced the stacking fault energy which results in the...
A higher content of Al in Mg alloys leads to the formation of the precipitation hardening intermetallic compound Mg17Al12. However, the rollability and the resulting ductility and formability of sheets of such alloys are reduced with increasing Al content. In this study, Mg alloys of the AZ- and AM- series were used to investigate the impact of the...
The present work investigates the influence of different shearing patterns on mechanical and forming behavior at room temperature of equal channel angular pressing (ECAP) processed AZ31 sheets. Hot-rolled AZ31 (Mg-3Al-1Zn, wt.%) sheets, with dimensions of 200 × 200 × 1.8 mm3, were processed at 225 °C with channel angle of 110° regarding processing...
Magnesium alloys containing rare earth elements have better properties in terms of formability, strength and corrosion resistance. Due to the tight supply situation these elements should be substituted partially or complete, for example by calcium. Microstructural studies of cast alloys of new compositions, and the influence of various heat treatme...
AZX310 alloy (Mg-3Al-1Zn-0.3Mn-0.5Ca in wt.%) sheets were produced via twin roll casting and subsequent warm rolling. The eutectic lamellae at the mid-thickness of the strip are changed during the rolling to fine spheroidal particles. The rolled sheets shows a large amount of fine Ca-rich particles which are homogeneously distributed through the wh...
The rolling of magnesium sheets is carried out in a process consisting of multiple passes with low degree of deformation per pass. The low degree of formability of magnesium and its alloys makes it necessary to carry our rolling in multiple steps. Alternatively, it has been shown that the extrusion of flat and thin plates is feasible.
This chapter indicates that wrought magnesium (Mg) alloys are attractive for automotive applications where light weighting is critical. For electron backscatter diffraction (EBSD) analysis, ∼10 mm wide and ∼15 mm long samples were cut from the sheet material using a diamond saw. One of the sample surfaces was mechanically polished and then electrop...
In this work the microstructure development during annealing of AZ31 sheets processed by equal channel angular pressing (ECAP) is presented. Samples with dimensions of 200 × 200 × 1.8 mm3 were processed in a single ECAP pass at 225 °C using a channel angle of 130°. Subsequent isothermal and isochronal heat treatments were used to reveal the microst...
AZ31 Mg alloy sheets were processed by equal channel angular pressing (ECAP) at 225 °C with a channel
angle of 110° regarding a strain path change.In consideration of mechanical anisotropy of Mg sheets, the
sheet was processed by ECAP along the rolling direction in the first pass. Subsequently, it was processed
along the transverse direction by 90°...
The deformation behavior of rolled Mg-Al-Zn and Mg-Zn-RE (rare earth) sheets after annealing was investigated in tension. The tensile axis was oriented in either the rolling direction (RD) or the transverse direction (TD). The deformation tests of the sheets were accompanied by in situ measurements of the acoustic emission (AE); AE signal analysis...
The present paper reviews the present potential of magnesium and its alloys as structural light-weight material in transportation industry. An overview will be given on the state of the art in casting technologies of magnesium alloys in order to broaden possible applications in light weight construction. Further, wrought magnesium will be emphasize...
The commercial application of magnesium alloy sheets is hindered by their low formability and therefore technological and economic constraints. Tailoring the texture has been identified as playing a major role in enhancing the formability of magnesium sheets. In this study, the formability of magnesium sheet ZE10 and AZ31 was investigated. While th...
Wrought magnesium (Mg) alloys are attractive for automotive applications where light-weighting is critical. One of the major challenges with conventional Mg alloys, such as Mg-3Al-1Zn(wt.%), is the strong texture formation after rolling and subsequent annealing, which results in anisotropic mechanical properties and poor cold formability [1]. It wa...
The rolling of magnesium sheets is carried out in a process consisting of multiple passes with low degree of deformation per pass. The low degree of formability of magnesium and its alloys makes it necessary to carry our rolling in multiple steps. Alternatively, it has been shown that the extrusion of flat and thin plates is feasible.
By applying t...
AZX310 alloy (Mg-3Al-1Zn-0.3Mn-0.5Ca in wt.%) sheets were produced via twin roll casting and subsequent warm rolling. The eutectic lamellae at the mid-thickness of the strip are changed during the rolling to fine spheroidal particles. The rolled sheets shows a large amount of fine Ca-rich particles which are homogeneously distributed through the wh...
The influence of texture on deformation behavior has been investigated for conventionally rolled magnesium slab and rolled twin roll cast (TRC) magnesium strip in form of sheets. The Mg-Zn-Rare earth alloy sheets were deformed at room temperature with the tensile axis oriented in the rolling (RD), 45° and the transversal direction (TD). The basal p...
Twin-roll casting of magnesium alloys is seen as a promising processing route to enable a further development of sheet properties. In this regard the influence of melt temperature and rolling speed on the microstructure and texture development of magnesium strips is investigated for alloy AZ31. Microstructure and through-thickness texture measureme...
In the present work, the influence of the additions of zinc, zirconium and cerium-rich mischmetal on the microstructural recrystallization development of magnesium were investigated. Grain size and chemical composition were the principal variables of the billets used for indirect extrusion experiments. Significant changes in the evolution of the dy...
Reducing vehicle weight and emissions by lightweight design is a major goal of the automotive industry. Magnesium as the lightest structural metal bears a significant weight saving potential compared to steels and aluminum. Cast magnesium components are widely used e.g. as engine blocks or gear box houses. The application of magnesium sheets is cur...
The inuence of texture on deformation behavior was investigated for conventionally rolled magnesium alloy slabs and rolled twin roll cast magnesium alloy strips in the form of sheets. The MgZn based sheets were deformed at room temperature with the tensile axis oriented in the rolling and transversal directions. The texture with respect to dierent...
Wrought MgZnCe alloy (ZE10) has been pre-compressed and subsequently subjected to tensile loading. Due to a bre texture of the samples, the level of pre-compression stress signicantly inuences the subsequent tensile behaviour. The acoustic emission technique was used for monitoring active deformation mechanisms during mechanical testing. The obtain...
In this work twin-roll cast AZ31 magnesium strip of thickness 5.6 mm was subjected to the heat treatment and further constrained groove pressing. A comparison of the microstructure and microhardness of as-cast, constrained groove pressed and annealed material was carried out. The twin-roll cast strip exhibits an inhomogeneous structure which is rep...
Reducing vehicle weight and emissions by lightweight design is a major goal of the automotive industry. Magnesium as the lightest structural metal offers a significant weight saving potential compared to steel and aluminum. However, the poor formability of magnesium semi-finished products (e.g. sheets) has hindered the massive application of this m...
Magnesium as the lightest structural metal offers significant potential weight saving compared with steel and aluminium. Cast magnesium components are widely used, e.g. as engine blocks or gear box housings. To open more opportunities for weight saving, it is necessary to widen the application fields to wrought products, such as large thin walled c...
Twin-roll casting is a technique which allows production of high quality thin magnesium alloys strips with enhanced microstructure. However, further treatment using severe plastic deformation technique or annealing is required to improve mechanical properties of strips. Equal channel angular pressing is a very effective tool for the grain refinemen...
