含钪Al-Cu-Li-Zr合金的热变形行为及组织演化

Hot deformation behavior and microstructural evolution of Al-Cu-Li-Zr alloy containing Sc

在实验温度范围为380~500℃、应变速率范围为0.001~10.0 s-1,采用Gleeble-1500热模拟机,对含钪Al-Cu-Li-Zr合金的高温热变形行为进行研究,采用金相显微镜和透射电镜观察合金在压缩变形时的组织变化。结果表明：变形温度和应变速率的变化强烈影响合金的流变应力,合金的流变应力随变形速率的增加而增大,随变形温度的升高而降低,可用包含Arrhenius项的Zener-Hollomon参数描述合金在高温压缩变形时的流变应力行为。当合金在温度低于440℃变形时,合金中主要形成亚晶组织,仅发生动态回复;在ln Z≤36.7变形时,合金发生部分动态再结晶,其动态再结晶形核机制主要为晶界弓出和亚晶合并形核。

The deformation behavior of Al-Cu-Li-Zr alloy containing Sc was investigated with compression tests in the temperature range of 380-470 ℃ and the strain rate range of 0.001-10.0 s-1 using Gleeble-1500 system,and the associated microstructural evolutions was studied by metallographic microscopy and transmission electron microscopy.The results indicate that the flow stress of the alloy increases with increasing strain rate at a given temperature,and decreases with increasing temperature at a given imposed strain rate.The flow stress of the alloy during the elevated temperature deformation can be represented by a Zener-Hollomon parameter with the inclusion of Arrhenius term.At 440 ℃,the hot deformation structure of the alloy is mainly the sub-grain structure,and when ln Z≤36.7,the dynamic recrystallization occurs in the alloy.The nucleation mechanism of recrystallizing process is grain-boundary protrude and subgrain coalescence.