查看更多>>摘要：? 2022 Acta Materialia Inc.Aiming at high-energy-density off-grid application, severe plastic deformation-modified Al-Li-Mg-Zn-Cu high-alloy aluminum obtained by deformation-driven modification was proposed to serve as anodes for primary aluminum-air batteries. Homogeneous microstructures induced by the fragmentation of second phases and dynamic recrystallization suppressed the formation of the hydroxides-eutectic skeletons to isolate anodes from alkaline electrolytes. The alloying elements contributed to the inhibition of hydrogen evolution self-corrosion, the mitigation of polarization, and the enhancement of the discharge voltage. The self-corrosion rate was only one-seventh of the 5N pure aluminum. The power and energy densities reached 88.3 mW cm?2 and 2.73 Wh g?1, respectively, which is better than those of pure aluminum.
查看更多>>摘要：? 2022 Acta Materialia Inc.An ultra-high anisotropic magneto-mechanical hysteresis-type damping (MMHD) with temperature and frequency insensitivity was found in Fe-18at.%Ga single crystals. The [111]-orientated Fe-Ga single crystal exhibits a damping value up to 0.13 (Q?1, equivalent to a special damping capacity SDC of 0.82) in the wide temperature range of ?100–150 °C, much higher than that of the conventional ferromagnetic high damping alloys (Fe-Cr/Al based alloys). For the [001]-orientated single crystal however, the MMHD value is almost zero despite the large magnetostrictive coefficient along [001] direction. Through magnetic domain analysis, it is demonstrated that MMHD originates from the stress-induced irreversible movement of 90° domain walls. The MMHD of Fe-Ga single crystals depends positively on the orientation factor, and the ultra-high relaxation strength is closely related to the magnetostriction in the [001] direction and the tetragonal magnetoelastic coupling constant.
查看更多>>摘要：? 2022 Acta Materialia Inc.The formation of metallic glass through melt processing proves to be the most challenging for pure monatomic face-centered cubic (FCC) metals. Though it has long been conjectured that amorphous monatomic metals can be generated through deforming a solid at room temperature, there is rarely direct evidence to prove that is indeed the case. In this study, mechanical loading was applied to nanometer-sized crystals inside an aberration-corrected transmission electron microscopy, and atomic-scale in situ evidence is provided of strain-induced amorphization in Pt and Ni near room temperature. The loading was applied in such a way that the stress state is complicated, and the strain distribution is non-uniform, restricting dislocation activities in accommodating the imposed strain. The local lattice distortion is then rendered so large and the associated strain energy is so high that the crystal collapses into the amorphous state. As such, even elemental FCC metals can be forced to become amorphous.
查看更多>>摘要：? 2022Twinning in a Ti?26Nb alloy during thermal cycling was investigated by transmission electron microscopy. The interrelationships between displacive transformation and twinning were proposed. Fine {112}β1ˉ1ˉ1β twins and preferentially formed ω particles were observed in the β matrix after 100 cycles. The {112}β1ˉ1ˉ1β twins nucleated in ω particles and grew by merging twin embryos. Upon further increasing the cycle number to 500, {332}β113ˉβ twins bounded with laminated α" martensite were observed instead. The interfacial twin boundary α" phase mediated the martensitic transformation of the adjacent region, leading to the formation of {332}β113ˉβ twins.
查看更多>>摘要：? 2022 The AuthorsDOI of original article: https://doi.org/10.1016/j.scriptamat.2021.114498 The publisher regrets that equation 3 has an error and the variable ‘l’ has been removed. The correct equation should read as follows: The publisher would like to apologise for any inconvenience caused.
查看更多>>摘要：? 2022 Acta Materialia Inc.Long-term tensile creep experiments were performed at 973 K on a family of multicomponent equiatomic solid solution alloys with face-centered cubic crystal structures, including quinary CoCrFeMnNi alloy and quaternary CoCrFeNi alloy, together with our previous report on ternary CoCrNi alloy. Analyzing the steady-state and transient creep properties and characterizing the precipitate evolution, it is suggested that dislocation creep be the dominant deformation mechanism for all these alloys. Although CoCrNi shows the highest room-temperature strength and the lowest creep rate at 973 K, the creep lifetime data for all three alloys are similar and can be described by the Monkman-Grant relationship.
查看更多>>摘要：? 2022 The Author(s)A new type of compositionally complex (medium- or high-entropy) M5Si3 silicides is synthesized. Both (V1/5Cr1/5Nb1/5Ta1/5W1/5)5Si3 and (Ti1/5Zr1/5Nb1/5Mo1/5Hf1/5)5Si3 form single-phase homogenous solid solutions. Notably, (V1/5Cr1/5Nb1/5Ta1/5W1/5)5Si3 forms the hexagonal γ (D88) phase, while all its five constituent binary silicides, V5Si3, Cr5Si3, Nb5Si3, Ta5Si3, and W5Si3, are stable in the tetragonal α (D8l) or β (D8m) phases. Annealing at 1600 °C demonstrates that this hexagonal γ phase is stable. Comparison of the experimental and calculated X-ray diffraction patterns, Rietveld refinements, and analysis of aberration-corrected scanning transmission electron microscopy high-angle annular dark-field images suggest cation ordering, which reduces the configurational entropy. This work expands the field of high-entropy and compositional complex ceramics by not only discovering a new compositionally complex silicide phase but also demonstrating cation ordering and unusual phase stability. These compositionally complex silicides can be combined with refractory high-entropy alloys to make the high-entropy counterparts to the Nb-silicide and Mo-Si-B composites.
查看更多>>摘要：? 2022 Acta Materialia Inc.The interphase precipitation behaviors and resultant hardening in V-microalloyed low carbon steels combined with Nb or Ti addition were investigated. After isothermal transformation at 923 K, alloy carbide is formed by simultaneous interphase precipitation of carbide-forming elements, with the enrichment of Nb or Ti rather than V at the early stage due to their larger driving force for precipitation. When compared at the same total amount of microalloying addition, both number density and size of alloy carbide, as well as resultant hardness of ferrite in the multiple-added alloys are in between those of the single-added counterparts. The advantage of multiple microalloying of elements with different carbide-forming tendency is summarized to be the co-establishment of high number density and large volume fraction of alloy carbide with acceptable austenitizing temperature required for complete dissolution of the added carbide-forming elements.
查看更多>>摘要：? 2022 Acta Materialia Inc.Deformation and subsequent annealing are often combined to optimize the overall mechanical properties of metallic materials. In this work, the strength-ductility trade-off between dynamic plastic deformation (DPD)-induced and annealed DPD structures in Cu and Cu-4.5Al alloy was compared. The strength-ductility combination of the DPD Cu samples is inferior to that of the annealed DPD Cu samples, while the strength-ductility synergy of the DPD Cu-4.5Al samples is comparable to that of the annealed DPD Cu-4.5Al samples, for which the reasons were analyzed based on the tensile deformation mechanism of these samples. This work suggested that high performance metallic materials can be obtained by just one-step plastic deformation without subsequent annealing treatment, which would be an economic and effective way to improve the strength-ductility combination of face-centered-cubic metals and alloys with a low stacking fault energy.
查看更多>>摘要：? 2022A rejuvenated Zr-based bulk metallic glass is tested in tension: it shows strain-hardening and reaches 0.9% plastic strain at failure. The initial rate of increase of flow stress with strain is 73 GPa, much higher than normal for polycrystalline metals and alloys. This hardening rate and its decay with increasing strain are compared with published data on a representative range of conventional and novel alloys. Taking the onset of necking as failure, and using Considère's analysis, we conclude that the metallic glass, however much rejuvenated, is limited to tensile plastic strains of approximately 1%, because of the rapid decay of hardening rate with strain. Rejuvenation of the metallic glass blocks early catastrophic failure in a predominant shear orientation. In comparison with as-cast samples, the fracture surface of the rejuvenated sample is more rugged and the characteristic vein pattern is denser. The effects of rejuvenation on abrasive-wear behavior are also examined.
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