Abstract 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 × 10−5 to 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.

中文翻译：

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从低熵到高熵的面心立方金属合金中的 Portevin-Le Chatelier 机制

摘要 对某些具有扩散溶质原子的合金进行拉伸试验时的锯齿现象（即 Portevin-Le Chatelier 效应）已被观察到很长时间，但详细的机制尚不完全清楚。本研究旨在通过对一系列单相面心立方 (FCC) 纯金属和合金：Ni、CoNi、CoFeNi、CoCrFeNi 和 CoCrFeMnNi 进行拉伸试验，从不同的方法中找出机理，它们的范围从低到高配置熵。在应变速率从 1 × 10−5 到 1 × 10−2/s 和温度从室温到 700 °C 条件下的拉伸试验结果表明，CoFeNi、CoCrFeNi 和 CoCrFeMnNi 合金的应力-应变曲线上出现锯齿在它们特定的温度和应变率范围内。提出了一种位错钉扎机制，并通过理论计算验证了现有置换合金。所提出的机制涉及通过“局部位错-核扩散”对置换溶质原子进行原位重排，也可能适用于类似的置换合金。