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(a) Vickers hardness as function of time of Mg-15 Gd-0.5 Zr rods aged at 180 °C and (b) true stressstrain curves of peak aged sample under tension along the ED at room temperature.
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A study regarding the effect of texture on tensile yield strength and hardness of an extruded Mg-15Gd-0.5Zr rod was performed, with a great emphasis laid on the relevant mechanisms. A 7% pre-tension along the extrusion direction (ED) in the solid solution condition was used to transform the texture from a broad distribution of basal poles with a pe...
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Mg-Y-Ni alloys with different second phases were designed by changing Y/Ni atomic ratio from 1.5 to 0.5. The microstructure and mechanical properties of as-cast and as-extruded alloys were investigated. The as-cast Mg-Y-Ni alloy with Y/Ni ratio of 1.5 is composed of α-Mg and long period stacking ordered (LPSO) phase. When Y/Ni ratio is equal to 1,...
Citations
... The rebound value of 1, 2 and 4% of FRI at − 20 °C was 1.12, 1.09 and 1.08 times, respectively, that at − 5 °C. The average grain size of the metal decreases after special processing [36,37]. The strength and hardness of the metal materials significantly improved with the decrease in grain size. ...
The uniaxial compressive strength (UCS) of ice materials, as an important indicate to assess safety of ice and snow buildings, is difficult to measure quickly using existing methods. The rebound method is widely used for the Non-Destructive Testing (NDT) of the UCS of building materials. Therefore, firstly, rebound methods of ice materials were established. In this study, the Leeb hardness tester and Schmidt hammer were selected to test plain ice and fiber-reinforced ice (FRI), respectively. Then, the rebound test and uniaxial compression test were performed under different temperatures (− 20, − 15, − 10 and − 5 °C) and different fiber content (0, 1, 2 and 4%). The result of rebound showed that the rebound value of 1, 2 and 4% FRI was 1.33, 1.09 and 1.08 times, respectively, that of plain ice at – 20 °C. The rebound value of plain ice at − 20 °C was 1.32 times higher than that at − 5 °C. Secondly, the correlation between rebound value and UCS of the ice material was established. The UCS of plain ice has a linear relationship with rebound value, while FRI exhibited a power law relationship. Finally, the rebound method was applied to field NDT of ice and snow buildings in Harbin. The test results showed that the estimated UCS of ice materials was conservative due to freezing patterns, and the error between the estimated and the measured UCS of the FRI was about 10%. The NDT method for ice materials in this study has a positive effect on the safety assessment of ice and snow building.
... De 50 para 77 % (reduções análogas àquelas das rotas 1 e 2, respectivamente) as maiores diferenças observadas pelos autores foram: A diminuição das frações das componentes GOSS e Brass-R1 e um aumento significativo da Brass (23). A textura (e mudanças na sua distribuição) influencia na deformação plástica, dureza e resistência mecânica dos materiais (24,25). ...
... Precipitados tendem a refinar a microestrutura ao ancorarem os contornos de grão, por um mecanismo conhecido como arraste de Smith-Zener (24,25). Ao retardar o movimento desses contornos as partículas atrasam a recristalização e o crescimento de grão, resultando em menores tamanhos de grão ao final do recozimento. ...
... Ao retardar o movimento desses contornos as partículas atrasam a recristalização e o crescimento de grão, resultando em menores tamanhos de grão ao final do recozimento. Para tamanhos não nanométricos, é consenso que a redução de tamanho de grão leva a um aumento da resistência mecânica e propriedades análogas (24,25). Esse fenômeno pode ser modelado pela equação empírica de Hall-Petch. ...
... In addition, the crystal orientation of 2060 AleLi alloy changed significantly after the shot impact, which further led to the evolution of material texture. The hardness of the material is also affected by the texture [43]. Fig. 19 shows the crystal orientation and texture evolution law of materials under different shot sizes. ...
The microstructure evolution and strengthening mechanism of materials after shot peening have always been the focus of research. In this paper, a novel coupled constitutive model was proposed to predict the depth of fine-grain of the 2060-T8 aluminum-lithium (Al–Li) alloy after shot peening. Besides, combining the numerical and experimental methods, the influences of shot size on yield stress, dislocation density, and crystal orientation of Al–Li alloy were systematically studied to reveal the strengthening mechanism. The results show that larger shot sizes can significantly improve the depth of the dislocation density layer and the fine-grain layer of 2060 Al–Li alloy. The depth of the refinement layer increases from 50 μm to 80 μm when the shot size grows from 0.3 mm to 0.6 mm. It is found the depth of the grain refinement layer in the experiment is consistent with the depth where is a sudden change of grain size in the simulation. Additionally, electron backscatter diffraction (EBSD) shows that many sub-grains are produced in the material due to high dislocation density, and the proportion of low-angle grain boundaries (LAGB) increases significantly, from 48.3% to more than 98.4%. The crystal orientation in the grain has changed obviously and Goss texture {100} obtained in the deformation band. In contrast, with the increase in shot size, the proportion of the Schmid factor with a high-level trend increases. However, the hardening effect of the material is much greater than the softening effect which results in higher yield stress and microhardness of the top surface.
... As a further investigation, texture analysis was performed on single-layer coatings to highlight the differences in growth among three constituent materials. Texture influences many coating properties, including mechanical [105,106], electrochemical [107,108] and tribological properties [8,109,110], and is therefore important to be accounted for. Pole figures [111,112] resulting from the texture analysis are reported in Figure 6 for the three monolithic coatings. ...
Nanolayered coating systems consisting of CrN alternated with Mo2N and W2N are deposited via DC magnetron sputtering. The impact of the bilayer period in a 200 to 10 nm regime on the mechanical and electrochemical properties of the coatings is investigated by means of XRD, SEM, TEM, Nanoindentation, Rockwell-C indentation and potentiodynamic polarization.
In both systems, coatings properties increase by reducing the bilayer period. Concerning CrN/W2N coatings, the improvement is complementary, with nanolaminates expressing good corrosion resistance and hardness from their constituent CrN and W2N constituents, respectively. As for the Crn/Mo2N system, both mechanical and corrosion resistance improve synergistically. The expressed properties are discussed in terms of structural and microstructural features as well on residual stresses within the coatings.
... Magnesium (Mg) is the eighth most abundant element on the Earth's crust , which exists in various forms such as oxides, carbides, chlorides, silicates, fluorides, sulfates, and phosphates. Mg alloys have been widely used in automobile, aerospace, and electronics industries owing to their high specific strength, high thermal and electrical conductivity, excellent electromagnetic shielding, damping, and shock absorption Razieh et al., 2021;Guo et al., 2017). However, Mg alloys have many unsatisfactory properties, such as poor corrosion and wear resistance, which severely limit their wide application prospects Hu et al., 2018). ...
High specific-strength magnesium-based materials are the promising substitute for traditional metallic materials like steel, but their easy corrosivity has caused serious resource waste and safely problems. Chemical conversion coating, as a primer coating for corrosion-resistant surface coating, has a great chance to provide primary and durable corrosion-resistant performance through rationally designed self-healing treatment for preventing further corrosion of damaged sites. Herein, this chapter provides a comprehensive and updated review of the advantages and limitations associated with various chemical conversion coating-based self-healing corrosion protection systems and their mechanisms of action. Self-healing chemical conversion coating tends to be autonomous healing mechanisms with minimal or no intervention, thus possessing the “smart” property. Therefore, self-healing chemical conversion coatings are focused on improving corrosion resistance, self-healing ability, repair durability, cost-efficiency, and environmental-friendliness, instead of the design of stimulation response mechanisms. The hope that obtains high-performance self-healing conversion coatings through tuning simple preparation technologies and multifunctional coating under the premise of simple preparation methods, which will be beneficial for sustainable development in the world.
... Thus this is the first time in situ observation of the strength enhancement of MoNbTaVW under stress along with the nucleation of dislocations. The formation of a strong texture is an effective way to improve strength, the similar discovery has also been reported in Mg alloys [56] and Al alloys [57]. The IPF of both samples during decompression are shown at the top of Fig. 6. ...
The excellent mechanical properties of high-entropy alloys (HEAs) make them promising materials for advances in science and technology. However, the underlying mechanism of plastic deformation is not well understood. In situ experiments are urgently required to provide a fundamental understanding of the plastic deformation under high pressure. We performed in situ synchrotron x-ray diffraction (XRD) experiments to study compression deformation behavior of the HEA MoNbTaVW in a radial diamond anvil cell (rDAC). Our results show that the strength and ratio of the stress-to-shear modulus values are ~1.5 and 3 times that of pure tungsten (W), respectively. MoNbTaVW showed plastic deformation above 5 GPa and displayed a much stronger texture. We found that the active dislocation behavior is mainly responsible for the high strength in MoNbTaVW under compression. This unique technique opens a new avenue to investigate the in-situ mechanical properties and their mechanism in other types of HEAs.
... The increment of TYS by ageing of the peak-aged H1 alloy (58 MPa) is lower than H2 and H3 alloys (60 and 67 MPa), which is mismatched with the increment in hardness. It has been reported that this mismatch is derived from the different deformation modes activated by uniaxial tension and hardness test [40]. ...
... It is easy to form basal texture for traditional magnesium (Mg) alloys, such as pure Mg and AZ31, after conventional deformation such as rolling or extrusion, resulting in poor ductility and formability at ambient temperature [1][2][3][4]. In the last decades, a non-basal texture which is beneficial to improving ductility and formability [5] has been reported in binary Mg-RE [6][7][8] and ternary Mg-Zn-RE [9][10][11][12][13][14][15] alloys. Depending on the processing, the non-basal texture shows different forms. ...
... In addition, dominant deformation mode in magnesium alloy with intensive basal texture is highly related to the loading direction and the second phase. If the tensile direction is parallel to the basal plane, the basal slip is hardly activated, while prismatic slip exhibits soft orientation [19]. The basal plates, such as SFs and LPSO phases, show higher resistance on the prismatic slip than the basal [20]. ...
... Some small lamellar LPSO phases in recrystallized grains precipitate dynamically during extrusion at 450°C. Some lamellar LPSO and rod-like β' phases coprecipitate during the artificial ageing carried out at 200°C following the LPSO and β precipitation sequence (α-Mg (SSSS) → I 2 stacking fault → γ' (hcp)→ LPSO (ordered hcp) and α-Mg (SSSS) → G.P. zones → β'' (D0 19 ) →β' (orthorhombic) → β 1 (fcc) → β (fcc) [41,42]). As reported [43], when the interlamellar spacing of the lamellas is narrow enough or the number density and sizes of short rods are large enough, β' phase can interact with the neighboring LPSO phase and the growth of short rods along c-axis can be restricted by the lamellas as a frame. ...
