Microscale deformation controlled by compositional fluctuations in equiatomic Nb–Mo–Ta–W alloys
Microscale deformation controlled by compositional fluctuations in equiatomic Nb–Mo–Ta–W alloys
复制标题
等原子 Nb-Mo-Ta-W 合金成分波动控制的微尺度变形
DOI：
10.1016/j.msea.2022.143892
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Marian, Jaime
中科院分区：
文献类型：
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作者：
Pozuelo, Marta;Marian, Jaime
已知高熵合金（HEA）化学成分的局部波动对其机械性能有重大影响。在这项工作中，我们最终建立了微米尺寸样品的强度与体心立方（bcc）难熔Nb-Mo-Ta-W HEA中等原子化学计量偏差之间的直接联系。我们对压缩后的微柱进行了详细的电子色散光谱（EDS）谱线分析，在室温和应变率在10−4和10−1s−1之间的原位扫描电镜微压缩测试。我们发现，微柱尖端附近的成分波动是屈服强度优于应变速率和晶粒取向的最佳定量预测因子。富W微柱尖端的屈服强度为1500 MPa，而富Ta和富nb微柱尖端的屈服强度分别为1000和700 MPa。最后，我们的高分辨率TEM分析揭示了大量边缘位错的存在，这表明由于缺乏足够的内部源，变形是由形核控制的。
Local fluctuations in the chemical composition of high-entropy alloys (HEA) are known to have a significant influence on their mechanical performance. In this work, we conclusively establish a direct link between the strength of micron-sized specimens and deviations from equiatomic stoichiometry in body-centered-cubic (bcc) refractory Nb–Mo–Ta–W HEA. We perform a detailed electron dispersive spectroscopy (EDS) line profile analysis of the compressed micropillars afterin-situscanning electron microscopy microcompression tests at room-temperature and strain rates between 10−4and 10−1s−1. We find that compositional fluctuations near the micropillar tip is the best quantitative predictor of yield strength over strain rate and grain orientation. In micropillars tip rich in W, we measure a yield strength of 1500 MPa, while for those with a Ta and Nb-rich oscillations, the yield strength is 1000 and 700 MPa, respectively. Finally, our high-resolution TEM analysis reveals the presence of numerous edge dislocations, suggesting that deformation is controlled by nucleation due to the absence of sufficient internal sources.