Size-dependent plasticity in an Nb25Mo25Ta25W25 refractory high-entropy alloy
Size-dependent plasticity in an Nb25Mo25Ta25W25 refractory high-entropy alloy
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DOI：
10.1016/j.actamat.2013.11.049
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发表时间：
2014-02-15
期刊：
影响因子：
9.4
通讯作者：
Spolenak, Ralph
中科院分区：
文献类型：
--
作者：
Zou, Yu;Maiti, Soumyadipta;Spolenak, Ralph
高熵合金（HEAs）是正在发展的多组分金属间体系，其中多个主元素倾向于形成具有强烈固溶强化倾向的单一固溶体状相。在这项研究中，Nb 25 Mo 25 Ta 25 W25耐火HEA通过电弧熔炼合成，并在1800 ℃下均匀化。单晶HEA柱在两个方向（[001]和[316]）和直径范围从2 μ m到200 nm的生产通过聚焦离子束铣削和压缩使用一个平冲头尖端在纳米压头。HEA柱体样品可以达到非常高的强度水平，类似于4-4.5 GPa，这是类似于3-3.5倍高于本体HEA的强度水平;同时，延展性显著提高。与纯Nb、Mo、Ta和W柱相比，HEA柱在绝对值和标准化值两者上均表现出比它们中的任何一个更高的强度，并且HEA柱还表现出相对低的压缩尺寸效应，如通过强度对柱直径的对数对数斜率所评估的。HEA的较高的强度水平和较低的尺寸依赖性可以归因于在原子长度尺度上由局部畸变引起的晶格电阻增加。归一化的强度，长度尺度和温度之间的相关性的体心立方结构的支柱进行说明，并严格讨论的相关性的尺寸效应斜率以及加和性的强化机制。(C)2013 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
High-entropy alloys (HEAs) are evolving multi-component intermetallic systems, wherein multiple principal elements tend to form single solid-solution-like phases with a strong tendency to solid solution strengthening. In this study, an Nb25Mo25Ta25W25 refractory HEA was synthesized by arc melting and well homogenized at 1800 degrees C. Single-crystalline HEA pillars in two orientations ([001] and [316]) and with diameters ranging from 2 mu m to 200 nm were produced by focused ion beam milling and compressed using a flat-punch tip in a nanoindenter. The HEA pillar samples can reach extraordinarily high strength levels of similar to 4-4.5 GPa, which is similar to 3-3.5 times higher than that of the bulk HEA; meanwhile the ductility is significantly improved. Compared to pure Nb, Mo, Ta and W pillars, the HEA pillars exhibit higher strengths than any of them in both absolute and normalized values, and the HEA pillars also show relatively low compressive size effects, as evaluated by the log log slope of strength vs. pillar diameter. The higher strength levels and lower size dependence for the HEA could be attributed to the increased lattice resistance caused by localized distortion at atomic length scales. The correlation between normalized strengths, length scales and temperatures for body-centered cubic structured pillars is illustrated, and the relevance of a size-effect slope as well as the additivity of strengthening mechanisms is critically discussed. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.