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建立了Mg-9Li-3Al-2.5Sr合金在不同热变形条件下的本构方程,并研究了热变形条件对材料显微组织的影响。结果表明,热变形过程中合金的流变应力与变形速率和变形温度之间的关系可以用本构方程Z=9.23×1011×[sinh(0.002 472 52σ)]3.75描述。材料变形过程中的稳态流变应力可以用双曲正弦函数描述。在高温低应变速率下,当三角晶界处应力集中的速率大于晶界扩散和滑移速率时,将产生裂纹。裂纹不断萌生扩展,最终导致材料失稳。
The constitutive equation of Mg-9Li-3Al-2.5Sr alloy under different thermal deformation conditions was established and the effect of thermal deformation conditions on the microstructure of the material was also studied. The results show that the relationship between the flow stress, the deformation rate and the deformation temperature of the alloy during hot deformation can be described by the constitutive equation Z = 9.23 × 1011 × [sinh (0.002 472 52σ)] 3.75. Steady-state flow stress during material deformation can be described by hyperbolic sine function. At high temperature and low strain rates, cracks occur when the rate of stress concentration at the triangular grain boundaries is greater than the rate of grain boundary diffusion and slip. Cracks continue to sprout and eventually lead to material instability.