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本文根据微细晶粒LC4合金的超塑变形试验结果,分析了超塑变形的微观过程,提出一个基于非固有晶界位错运动的超塑变形模型。根据此模型及其本构方程,当晶粒较大变形温度较高时,ε∝σ~2/d,且超塑变形过程由体自扩散所控制,变形的激活能约等于体自扩散激活能;当晶粒较小变形温度较低时,ε∝σ~2/d~2,且该过程由晶界自扩散所控制,变形的激活能约等于晶界自扩散激活能。在8.2～11.5μm 的晶粒尺寸和445～505℃条件下,根据此模型计算得到的 LC4超硬铝的超塑变形应变速率与实测数据符合得颇好。
In this paper, the microscopic process of superplastic deformation is analyzed based on the result of superplastic deformation test of fine grain LC4 alloy, and a superplastic deformation model based on dislocation motion of non-intrinsic grain boundary is proposed. According to this model and its constitutive equation, when the larger deformation temperature of the grain is higher, εασ ~ 2 / d, and the superplastic deformation process is controlled by the self-diffusion of the body. The activation energy of the deformation is approximately equal to the self-diffusion activation When the smaller deformation temperature of the grain is lower, εασ ~ 2 / d ~ 2, and the process is controlled by the self-diffusion of the grain boundary. The activation energy of the deformation is equal to the self-diffusion activation energy of the grain boundary. The strain rate of superplastic deformation of LC4 superhard aluminum calculated by this model is in good agreement with the measured data at grain sizes of 8.2-11.5μm and at 445-505 ℃.