Experimental Study Of High Purity Polycrystalline Aluminum Of Dynamic Recrystallization

The dynamic recrystallization and feature of flow stress of high-purity poly crystal line aluminum has been investigated in this thesis. The compression deformation was carried out on Gleeble-1500 thermal simulator at strain rates of 0.002, 0.02, 0.2, 2s-1 and at temperatures of 260, 400, 450, 500 ℃. The deformation microstructures were observed under polarized microscopy(POM) and transmission electron microscopy(TEM).The result indicated that both discontinuous dynamic recry stall ization(DDRX) and continuous dynamicrecrystallization(CDRX) can occur in high-purity polycrystalline aluminum. However, the stress oscillation of true stress-strain curves are not observed in this investigation when DDRX occurs , which is different from the multi-peak true strain-stress curve of DDRX taking place in ultra-high purity aluminum. The possible main nucleation mechanism of dynamic recrystallization of high-purity polycrystalline aluminum is coalescence of subgrains. Strain-induced boundary migration mechanism is also observed.There's a close relationship between the Zenner-Hollomon parameter(Z parameter) and the dynamic restoration behavior in high-purity polycrystalline Aluminum: Only dynamic recovery occurs when lnZ>28, DDRX when lnZ<21, and CDRX when 21