High-Temperature Nano-Indentation Creep Behavior of Multi-Principal Element Alloys under Static and Dynamic Loads
High-Temperature Nano-Indentation Creep Behavior of Multi-Principal Element Alloys under Static and Dynamic Loads
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DOI：
10.3390/met10020250
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发表时间：
2020-02
期刊：
影响因子：
2.9
通讯作者：
Maryam Sadeghilaridjani;S. Mukherjee
中科院分区：
文献类型：
--
作者：
Maryam Sadeghilaridjani;S. Mukherjee
在各种结构应用中，蠕变是一个严重的问题，降低了组件的效率和使用寿命。多主元素合金由于具有良好的高温力学性能而成为新一代结构材料。本文采用纳米压痕技术研究了CoCrNi和CoCrFeMnNi两种多主元素合金在298 ~ 573 K的温度范围内，外加1000 mN的静态和动态载荷下的时效塑性变形行为。应力指数在15 ~ 135之间，表明位错蠕变是主导机制。CoCrNi和CoCrFeMnNi合金的激活体积均为~25b3，处于位错滑动的范围内。应力指数随压痕深度的增加而增加，这是由于位错密度和缠结的增加，而由于热激活位错，应力指数随温度的升高而降低。将两种多主元素合金的结果与纯Ni进行了比较。CoCrNi的蠕变位移最小，活化能最高，具有较好的抗蠕变性能。
Creep is a serious concern reducing the efficiency and service life of components in various structural applications. Multi-principal element alloys are attractive as a new generation of structural materials due to their desirable elevated temperature mechanical properties. Here, time-dependent plastic deformation behavior of two multi-principal element alloys, CoCrNi and CoCrFeMnNi, was investigated using nano-indentation technique over the temperature range of 298 K to 573 K under static and dynamic loads with applied load up to 1000 mN. The stress exponent was determined to be in the range of 15 to 135 indicating dislocation creep as the dominant mechanism. The activation volume was ~25b3 for both CoCrNi and CoCrFeMnNi alloys, which is in the range indicating dislocation glide. The stress exponent increased with increasing indentation depth due to higher density and entanglement of dislocations, and decreased with increasing temperature owing to thermally activated dislocations. The results for the two multi-principal element alloys were compared with pure Ni. CoCrNi showed the smallest creep displacement and the highest activation energy among the three systems studied indicating its superior creep resistance.