Microstructure evolution and deformation mechanisms during high rate and cryogenic sliding of copper
Microstructure evolution and deformation mechanisms during high rate and cryogenic sliding of copper
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DOI：
10.1016/j.actamat.2018.09.016
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发表时间：
2018-12-01
期刊：
影响因子：
9.4
通讯作者：
Greiner, Christian
中科院分区：
文献类型：
--
作者：
Chen, Xiang;Schneider, Reinhard;Greiner, Christian
摩擦滑动导致亚表层和底层材料之间的微观结构出现明显的不连续性，这对摩擦学性能产生了很大影响。在这里，应变速率和温度依赖性的摩擦诱导的微观结构演变过程中往复滑动铜系统地研究。结果发现，应变速率的增加和温度的降低，每个结果在一个过渡的主导变形机制从位错滑移孪晶介导的塑性在滑动的最开始。在高速和/或低温滑动条件下，揭示了一系列变形机制（应变速率近似10（4）s（-1）;液氮温度）：第一道次前冲时，在表面下形成纳米级位错迹线;第二道次后冲时，部分位错从滑动表面形核，并伴有纳米级孪晶和大量层错;第三，在进一步滑动时形成纳米晶层。滑动诱导的表面粗糙化被发现，以协助部分位错形核从表面在高速率和低温滑动。我们的研究结果表明，滑动表面可以作为一个有效的位错源，启动和适应相关的塑性变形，这可能是探索滑动过程中的微观结构演变模型。(C)2018 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Frictional sliding induces a distinct discontinuity in the microstructure between a subsurface layer and the underlying bulk material, which strongly influences the tribological performance. Here, the strain rate and temperature dependence of such tribologically induced microstructure evolution was systematically investigated during reciprocating sliding of copper. It was found that an increase in strain rate and a decrease in temperature each result in a transition in the dominating deformation mechanism from dislocation slip to twinning-mediated plasticity at the very beginning of sliding. A sequence of deformation mechanisms was revealed under high rate and/or cryogenic sliding (strain rate similar to 10(4) s(-1); liquid nitrogen temperature): First, nanoscale dislocation trace lines form beneath the surface during the first forward pass; Second, partial dislocation nucleation from the sliding surface accompanied by nano twinning and abundant stacking faults in the backward pass; Third, formation of a nanocrystalline layer upon further sliding. Sliding induced surface roughening is found to assist partial dislocation nucleation from the surface during high rate and cryogenic sliding. Our results suggest that the sliding surface can act as an effective source of dislocations to initiate and accommodate associated plastic deformation, which may be explored to model the microstructure evolution during sliding. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.