Portevin-Le Chatelier mechanism in face-centered-cubic metallic alloys from low to high entropy
Portevin-Le Chatelier mechanism in face-centered-cubic metallic alloys from low to high entropy
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DOI：
10.1016/j.ijplas.2019.07.003
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发表时间：
2019-11
影响因子：
9.8
通讯作者：
C. Tsai;Chi Lee;Po-Ting Lin;Xie Xie-Xie;Shuying Chen;R. Carroll;M. Leblanc;Braden A. W. Brinkman;P. Liaw;K. Dahmen;J. Yeh
中科院分区：
文献类型：
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作者：
C. Tsai;Chi Lee;Po-Ting Lin;Xie Xie-Xie;Shuying Chen;R. Carroll;M. Leblanc;Braden A. W. Brinkman;P. Liaw;K. Dahmen;J. Yeh
某些具有扩散溶质原子的合金在拉伸测试期间出现锯齿现象（即，Portevin-Le Chatelier效应）已经观察了很长时间，但详细的机制还不完全清楚。本研究的目的是找到从不同的方法通过拉伸测试验证的一系列单相面心立方（FCC）纯金属和合金：Ni，CoNi，CoFeNi，CoCrFeNi，和CoCrFeMnNi，从低到高的配置熵。应变速率为1 × 10− 5 ~ 1 × 10−2/s，温度为室温~ 700 °C的拉伸试验结果表明，CoFeNi、CoCrFeNi和CoCrFeMnNi合金在其特定温度和应变速率范围内的应力-应变曲线上出现锯齿。提出了位错钉扎的机制，并通过理论计算验证了该机制。所提出的机制涉及的替代溶质原子的原位重排的“局部位错芯扩散”，也可能适用于类似的替代合金。
Serration phenomena during tensile testing on certain alloys with diffusing solute atoms (i.e., Portevin–Le Chatelier effect) have been observed for a long time, but detailed mechanisms are not fully clear yet. This study is intended to find the mechanism from different approaches verified by tensile testing on a series of single-phase face-centered-cubic (FCC) pure metal and alloys: Ni, CoNi, CoFeNi, CoCrFeNi, and CoCrFeMnNi, which range from low to high configurational entropy. The results of tensile tests, at strain rates from 1 × 10−5to 1 × 10−2/s and temperature from room temperature to 700 °C, show that serrations occur on stress-strain curves of CoFeNi, CoCrFeNi, and CoCrFeMnNi alloys in their specific temperature and strain-rate regime. A mechanism for dislocation pinning is proposed and verified with theoretical calculation for the present substitutional alloys. The proposed mechanism involves the in-situ rearrangement of substitutional solute atoms by “local dislocation-core diffusion” and might also be applied to similar substitutional alloys.