Fe40Mn20Cr20Ni20高熵合金的低温动态拉伸变形机制

Dynamic Tensile Deformation Mechanisms of Fe40Mn20Cr20Ni20 High-Entropy Alloys at Cryogenic Temperatures

摘要:

探讨了Fe₄₀Mn₂₀Cr₂₀Ni₂₀高熵合金（HEA）在高/低温以及高应变率（分离霍普金森杆）条件下的力学行为和微观机制，并利用相关理论模型来拟合该HEA的屈服强度和流动应力。拉伸测试结果表明，在降低温度或增加应变率的条件下，该HEA表现出优异的强度-塑性协同效应和出色的变形硬化能力。在动态拉伸过程中，不同形式的位错和变形孪晶之间的相互作用共同提高了HEA的强度和变形硬化能力。Zerilli-Armstrong本构模型被用于预测HEA屈服强度的温度敏感性和应变率敏感性。同时，泰勒模型被用于预测HEA在动态拉伸作用下随应变率变化的流动应力，并将该模型应用于低温动态实验中。拟合结果与实验结果一致，为后续对HEA的强度预测提供了理论依据。

Abstract:

The mechanical behavior and microscopic mechanism of the Fe₄₀Mn₂₀Cr₂₀Ni₂₀ high-entropy alloy (HEA) at high/cryogenic temperatures and high strain rates (split Hopkinson bar) were investigated, and relevant theoretical models were used to fit the yield strength and flow stress of HEA. The tensile test results show that HEA exhibits excellent strength-plasticity synergy and excellent work-hardening ability by reducing the temperature or increasing the strain rate. During the dynamic tensile process, the interactions between different forms of dislocations and deformation twins jointly improve the strength and work-hardening ability of HEA. The Zerilli-Armstrong constitutive model was used to predict the temperature sensitivity and strain-rate sensitivity of the yield strength of HEA. At the same time, the Taylor model was used to predict the flow stress change of HEA with the strain rate under dynamic tension, and the model was applied to low-temperature dynamic experiments. The fitting results are consistent with the experimental results, providing a theoretical basis for the subsequent prediction of HEA strength.