Dislocation nucleation during nanoindentation in a body-centered cubic TiZrHfNb high-entropy alloy

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• 作者：Y.X. Ye^a ; Z.P. Lu^b ; T.G. Nieh^a ; ^{tnieh@utk.edu}
• 关键词：High-entropy alloy ; Nanoindentation ; Dislocation nucleation ; Activation volume and energy
• 刊名：Scripta Materialia
• 出版年：2017
• 出版时间：15 March 2017
• 年：2017
• 卷：130
• 期：Complete
• 页码：64-68
• 全文大小：758 K
• 卷排序：130

文摘

Pop-in behavior of a single-phase, body-centered cubic TiZrHfNb high-entropy alloy was characterized using instrumented nanoindentation. The critical shear stress required for the first pop-in was close to the theoretical strength, indicating it was controlled by dislocation nucleation. Data were collected and analyzed using a model based upon the transition-state theory and Weibull statistics. The activation volume for the pop-in events was evaluated to be about 3–5 atomic volumes, much larger than that in pure metals (~ one atomic volume), suggesting cooperative migration of multiple atoms. The activation energy was also estimated and compared favorably with the nucleation of a full-dislocation.