Effect of thermomechanical processing on microstructure and mechanical properties of CoCrFeNiMn high entropy alloy
Effect of thermomechanical processing on microstructure and mechanical properties of CoCrFeNiMn high entropy alloy
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DOI：
10.1016/s1003-6326(18)64727-2
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发表时间：
2018-05-01
影响因子：
4.5
通讯作者：
Peng, Liang-ming
中科院分区：
文献类型：
--
作者：
Fu, Jian-xin;Cao, Cheng-ming;Peng, Liang-ming
采用均匀化、冷轧和再结晶工艺制备了CoCrFeNiMn高熵合金。利用X射线衍射仪（XRD）、光学显微镜（OM）、扫描电镜（SEM）和多功能试验机研究了不同温度下形变热处理对合金组织和拉伸性能的影响。结果表明，铸造合金中枝晶组织再结晶后转变为等轴晶，并出现单一的面心立方（FCC）相。最细化的合金，来自最高的轧制比（40%），由于晶界强化，具有最高的强度，而延伸率随温度的变化呈现凹形特征。对于粗晶合金，塑性和加工硬化能力均随温度升高而单调下降。在中温下观察到的锯齿状流动归因于位错的有效钉扎，这表明动态应变硬化的发生并导致塑性的劣化。此外，断口上的韧窝也是典型的韧性断裂模式。
The CoCrFeNiMn high entropy alloy was produced by homogenization, cold rolling and recrystallization. The effects of thermomechanical processing on micro structures and tensile properties at different temperatures were investigated using X-ray diffractometry (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and multi-functional testing machine. The results show that dendritic structures in cast alloy evolve into equiaxed grams after being recrystallized, with single face-centered cubic (FCC) phase detected The most refined alloys, stemming from the highest rolling ratio (40%), exhibit the highest strength due to the grain boundary strengthening, while the variation of elongation with temperature shows a concave feature. For the coarse-grained alloys, both the ductility and work hardening ability decrease monotonically with increasing temperature. Serrated flow observed at intermediate temperatures is attributed to the effective pinning of dislocations, which manifests the occurrence of dynamic strain hardening and results in the deterioration in ductility. Besides, dimples on the fracture surfaces indicate the typical ductile rupture mode.