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Martensite transformation induced superplasticity and strengthening in single crystalline CoNiCrFeMn high entropy alloy nanowires: A molecular dynamics study
Materials Science and Engineering: A ( IF 6.4 ) Pub Date : 2020-07-08 , DOI: 10.1016/j.msea.2020.139853
Jianwei Xiao , Chuang Deng

In this work, we report simultaneous superplasticity and strengthening in single crystalline face-centered cubic (FCC) CoNiCrFeMn high entropy alloy (HEA) nanowires through synergistic martensitic phase transformation and micro-twin nucleation as revealed by molecular dynamics simulations. Furthermore, in contrast to the irreversible martensite transformation that has been previously reported in bulk HEAs under high pressure, the martensitic transformation in HEA nanowires is found to be reversible upon reverse loading. Shape memory effects can thus be enabled in HEA nanowires, although such effects are found to be mitigated for some orientations due to stacking fault crossing. Those mechanisms are dramatically different from deformation twinning dominated superplasticity in conventional FCC metal and intermetallic nanowires. While deformation twinning is still observed in FCC HEA nanowires, three pathways are found and in particular. All the novel mechanical behaviors in FCC CoNiCrFeMn HEA nanowires reported in this study can be explained by their unique negative stacking fault and martensite energies, which may shed some light on understanding the mechanical behavior of general HEAs under more complicated loading conditions.



中文翻译:

马氏体相变诱导单晶CoNiCrFeMn高熵合金纳米线的超塑性和增强:分子动力学研究

在这项工作中,我们通过分子动力学模拟揭示了通过协同马氏体相变和微孪晶成核,单晶面心立方(FCC)CoNiCrFeMn高熵合金(HEA)纳米线同时具有超塑性和强化作用。此外,与先前在高压下在批量HEA中报道的不可逆马氏体转变相反,发现HEA纳米线中的马氏体转变在反向加载时是可逆的。尽管发现由于堆叠故障交叉而在某些方向上减小了这种效应,但是因此可以在HEA纳米线中启用形状记忆效应。这些机制与传统的FCC金属和金属间纳米线中的变形孪晶主导的超塑性显着不同。尽管在FCC HEA纳米线中仍观察到变形孪生,但特别是发现了三种途径。这项研究中报道的FCC CoNiCrFeMn HEA纳米线中所有新颖的力学行为都可以用它们独特的负堆垛层错和马氏体能量来解释,这可能有助于理解普通HEA在更复杂的负载条件下的力学行为。

更新日期:2020-07-13
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