Al-4.10Cu-1.42Mg-0.57Mn-0.12Zr合金热变形过程中显微组织动态演化的表征(英文)

在Gleeble-1500热模拟机上对Al-4.10Cu-1.42Mg-0.57Mn-0.12Zr合金在变形温度300°C和应变速度10 s-1下进行热压缩变形,真应变分别为0.2、0.4、0.6和0.8。通过X射线衍射仪、扫描电镜和透射电镜研究合金变形过程中复杂的动态显微组织演变。结果表明:真应力随着应变的增加而迅速增大至峰值,之后随着应变的增加而趋于稳定,呈现动态软化特征。随着应变的增大,位错缠结成胞状与亚晶结构,表明变形过程中发生动态回复。动态析出相S相、θ相和Al3Zr相在变形过程中粗化速度加快。铝基体中析出连续的S相,并发现有不连续的S相在Al3Zr相附近和亚晶界处形核析出。Al3Zr相相对比较稳定,易于在位错和亚晶界处析出。流动软化机制是由于动态回复和动态析出导致位错密度减少而引起的。

Characterization of dynamic microstructure evolution during hot deformation of Al–4.10Cu–1.42Mg–0.57Mn–0.12Zr alloy

The Al–4.10Cu–1.42Mg–0.57Mn–0.12Zr alloy was compressed to different strains at deformation temperature of 300 °C and strain rate of 10 s^–1 on Gleeble–1500 system. The dynamic complex microstructures evolutions were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The true stress–true strain curves exhibited a peak stress at critical strain, after which the flow stresses decreased monotonically, showing a dynamic flow softening. As the strain increased, the dislocation tangled to cell structure and sub-grain structure, which indicated the occurrence of dynamic recovery during deformation. Dynamic precipitations of S (Al₂CuMg), θ (Al₂Cu) and Al₃Zr phase were accelerated and coarsened by deformation. Continuous S phases precipitated in the Al matrix and discontinuous S phases were found to be nucleated near the Al₃Zr phase and at the sub-grain boundary. The flow softening mechanism was resulted from the reduction of dislocation density which attributed to dynamic recovery and precipitates coarsening.