Dynamic softening mechanism of 30 % SiCp/2024Al composite during hot deformation process

摘要

Using Gleeb-1500D simulator, the isothermal compression tests of 30% SiCp/2024Al (volume fraction) are conducted at a temperature range of 623K - 773K and a strain rate range of 0.01s(-1) - 10s(-1). The softening mechanism of composites during hot deformation has been proposed based on the Zener-Hollomon parameter Z, deformation temperature T and microstructure analysis. Cross slip of dislocation plays a dominant role under the conditions of lnZ59.634 and T673K. While, deformation mechanisms such as cross slip, climb of dislocation and unzipping of the three dimensional dislocation network play a joint role when lnZ61.933 and T623K. Particularly, dynamic recrystallization occurred when lnZ55.669 and T723K. The cross slip, climb and unzipping of dislocation and dynamic recrystallization are the main softening mechanisms. The role of the dynamic recrystallization mechanisms become more significant and the critical strain of dynamic recrystallization decrease with the decrease of lnZ. Dynamic recrystallization nucleation mechanisms are mainly constituted of the subgrain combination and the bulging of the grain boundary.