Yield and flow properties of ultra-fine, fine, and coarse grain microstructures of FeCoNi equiatomic alloy at ambient and cryogenic temperatures
Yield and flow properties of ultra-fine, fine, and coarse grain microstructures of FeCoNi equiatomic alloy at ambient and cryogenic temperatures
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DOI：
10.1016/j.scriptamat.2023.115392
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发表时间：
2023-06
影响因子：
6
通讯作者：
A. Lavakumar;S. Yoshida;Jesada Punyafu;S. Ihara;Yan Chong;H. Saito;N. Tsuji;M. Murayama
中科院分区：
文献类型：
--
作者：
A. Lavakumar;S. Yoshida;Jesada Punyafu;S. Ihara;Yan Chong;H. Saito;N. Tsuji;M. Murayama
目前的研究揭示了Hall-Petch关系，或平均晶粒尺寸控制，和流动性能的等原子FeCoNi合金具有不同的晶粒尺寸在室温（298 K）和低温（77 K）。首次通过高压扭转和随后的退火在FeCoNi合金中实现了从超细晶区（0.7 μm）到粗晶区（145.3 μm）的各种平均晶粒尺寸。拉伸屈服强度强烈地依赖于温度和晶粒尺寸。Hall-Petch曲线表明，晶界强度系数对温度不敏感，而摩擦应力随着温度的降低而增加。对于所有的晶粒尺寸，强度和塑性都随着温度的降低而增加。位错滑移是影响室温力学性能的主要因素。在低温下，另一方面，纳米孪晶出现作为一个额外的变形机制，除了位错滑移。
The current study reveals the Hall-Petch relationship, or mean grain size control, and flow properties of equiatomic FeCoNi alloy having different grain sizes at room temperature (298 K) and cryogenic temperature (77 K). For the first time, various mean grain sizes ranging from the ultra-fine regime (0.7 μm) to the coarse grain regime (145.3 μm) were achieved in a FeCoNi alloy by high-pressure torsion and subsequent annealing. The tensile yield strength depends strongly on temperature and grain size. Hall-Petch plots demonstrate that the grain boundary strength coefficient is insensitive to the temperature, whereas friction stress increases as the temperature decreases. For all the grain sizes both strength and ductility were increased with decreasing the temperature down to 77 K. Dislocation slip is responsible for the room temperature mechanical properties. At cryogenic temperature, on the other hand, nano twinning appears as an additional deformation mechanism in addition to the dislocation slip.