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采用Gleeble-1500热模拟试验机和透射电子显微镜研究了变形温度为300~900℃,应变速率为0.01~10s-1条件下Al_2O_3/Cu复合材料的高温流变行为和组织演变规律,并利用Arrhenius关系和Zener-Hollomn参数构建了合金的峰值屈服应力、变形温度和应变速率三者之间的本构方程。结果表明:Al_2O_3/Cu复合材料的流变应力-应变曲线为典型的动态再结晶类型,其曲线由加工硬化、动态软化和稳定流变3个阶段组成,当变形温度一定时,流变应力随应变速率的增大而增大,而当应变速率固定时,流变应力随变形温度的升高而减小;求解得到复合材料的结构因子lnA为15.2391,应力水平参数a为0.020788mm~2/N,应力指数n为5.933035,变形激活能Q为2.1697×10~5kJ/mol;随着变形温度的升高,基体内位错密度逐渐下降,并呈现出明显的再结晶特征,而当固定变形温度时,随着应变速率的增大,基体内位错密度呈先增大后下降趋势。基于微观组织演变和热加工图,Al_2O_3/Cu复合材料的最佳热加工参数范围为热加工温度500~850℃、应变速率低于0.1s-1。
The high temperature rheological behavior and microstructure evolution of Al_2O_3 / Cu composites were studied by using Gleeble-1500 thermal simulator and transmission electron microscope at temperatures ranging from 300 ℃ to 900 ℃ and strain rates from 0.01 to 10s-1. Arrhenius Relationship and Zener-Hollomn parameters constitutive equations of the alloy peak stress, deformation temperature and strain rate were constructed. The results show that the flow stress-strain curve of Al 2 O 3 / Cu composites is a typical type of dynamic recrystallization. The curves consist of three stages of work-hardening, dynamic softening and steady-state rheological. When the deformation temperature is constant, the flow stress- When the strain rate is constant, the flow stress decreases with the increase of the deformation temperature. The structural factor lnA of the composite material is 15.2391 and the stress level parameter a is 0.020788mm2 / N, the stress exponent n is 5.933035 and the deformation activation energy Q is 2.1697 × 10 ~ 5kJ / mol. With the increase of the deformation temperature, the dislocation density gradually decreases and exhibits obvious recrystallization characteristics. With the increase of strain rate, the dislocation density in the matrix firstly increases and then decreases. Based on the microstructure evolution and hot working diagram, the optimum thermal processing parameters of Al 2 O 3 / Cu composites range from hot working temperature of 500 ~ 850 ℃ and strain rate of less than 0.1s-1.