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采用高温压缩实验研究了新型Al-Zn-Mg-Cu高强铝合金在温度300~450℃、应变速率0.001~10 s-1和压缩变形程度30%~80%范围内的热变形行为和组织演变。分析了该合金在实验参数范围内变形的应力-应变曲线特征。动力学分析获得该合金热变形的应力指数和激活能分别为4.97和150.07 kJ/mol,表明合金的热变形主要受扩散所控制。金相组织观察发现,随着变形温度的升高或应变速率的降低,变形组织晶内析出相逐渐溶入基体组织,晶内组织逐渐趋于均匀;同时粗大的晶粒沿变形方向拉长,晶界难溶相的碎化和弥散化程度增大。TEM和EBSD(electron back-scattered diffraction)组织分析表明,该合金在高温压缩变形过程中组织演变主要是亚晶的形成和完善的过程,热变形组织演变机理为动态回复和大应变几何动态再结晶。
The hot deformation behavior and microstructure evolution of a novel Al-Zn-Mg-Cu high-strength aluminum alloy were investigated by high-temperature compression at a temperature of 300-450 ℃, a strain rate of 0.001-10 s-1 and a compressive deformation range of 30-80% . The stress-strain curve characteristics of the alloy under the experimental parameters were analyzed. The kinetic analysis shows that the stress exponent and activation energy of this alloy are 4.97 and 150.07 kJ / mol, respectively, indicating that the thermal deformation of the alloy is mainly controlled by diffusion. Metallographic observation shows that with the increase of deformation temperature or strain rate, the precipitated phase in the deformed microstructure gradually dissolves into the matrix structure, and the microstructure of the microstructure gradually becomes uniform. At the same time, coarse grains elongate along the deformation direction, The degree of fragmentation and dispersion of the grain boundary hardly soluble phase increases. TEM and EBSD (electron back-scattered diffraction) microstructure analysis showed that the microstructure evolution of the alloy during the high temperature compressive deformation is mainly the formation and improvement of subgrain. The mechanism of the hot deformation microstructure is dynamic recovery and large strain geometric dynamic recrystallization .