Grain growth and Hall-Petch relationship in a refractory HfNbTaZrTi high-entropy alloy
Grain growth and Hall-Petch relationship in a refractory HfNbTaZrTi high-entropy alloy
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DOI：
10.1016/j.jallcom.2019.04.291
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发表时间：
2019-07-30
影响因子：
6.2
通讯作者：
Liaw, Peter K.
中科院分区：
文献类型：
--
作者：
Chen, Shuying;Tseng, Ko-Kai;Liaw, Peter K.
考虑到高温应用的潜力，了解温度变化对高温高熵合金（RHEAs）微观组织演变的影响尤为重要。在这里，我们实验研究了HfNbTaZrTi RHEAs在1000到1200摄氏度的温度下进行再结晶过程中的晶粒生长行为，并进行了冷轧，厚度减少了70%。通过经典的晶粒生长动力学分析，得到了两个活化能：在1000 ~ 1100℃范围内205 kJ/mol，在1100 ~ 1200℃范围内401 kJ/mol，表明晶粒生长有两种机制。屈服强度与晶粒尺寸的关系可以用Hall-Petch关系式(σ (y) = 942+ 270D(-0.5))很好地描述。结果表明，HfNbTaZrTi HEA的摩擦应力为942 MPa，高于钨合金，表明BCC-RHEA具有较高的本质应力。该系数为270 MPa/ μ m(-1/2)，远低于316不锈钢和Al0.3CoCrFeNi HEAs，晶界强化程度较低。(C) 2019 Elsevier B.V.版权所有
Understanding the effect of temperature variation on the microstructural evolution is particularly important to refractory high-entropy alloys (RHEAs), given their potential high-temperature applications. Here, we experimentally investigated the grain-growth behavior of the HfNbTaZrTi RHEAs during recrystallization at temperatures from 1,000 to 1,200 degrees C for varied durations, following cold rolling with a 70% thickness reduction. Following the classical grain-growth kinetics analysis, two activation energies are obtained: 205 kJ/mol between 1,000 and 1,100 degrees C, and 401 kJ/mol between 1,100 and 1,200 degrees C, which suggests two mechanisms of grain growth. Moreover, the yield strength - grain size relation was found to be well described by the Hall-Petch relation in the form of sigma(y) = 942+ 270D(-0.5). It was revealed that the friction stress, 942 MPa, in the HfNbTaZrTi HEA is higher than that of tungsten alloys, which indicates the high intrinsic stress in the BCC-RHEA. The coefficient, 270 MPa/mu m(-1/2), is much lower than that in the 316 stainless steel and Al0.3CoCrFeNi HEAs, which indicates low grain-boundary strengthening. (C) 2019 Elsevier B.V. All rights reserved.