Strain Hardening behavior of Al-Sc alloys

Abstract

Al-Sc alloys have been the subject of interest due to their superior mechanical properties as high strength aluminum alloys. To achieve benefits of these developments, it is essential to understand the relation between microstructural characteristics and macroscopic behavior of these alloys. Commercial pure aluminum (CPAl) and Al-2Sc master alloys were taken as the starting materials. The samples were cast in wedge shape and rolled such that that in a single pass various deformation levels can take place. The rolling was carried out at room temperature, 230K and 473K. The strain hardening behavior of Al-1wt.%Sc alloy was studied and correlated with Al. Because it is observed that Al-1wt.%Sc alloy showed better strain hardening behavior compared to other Al-Sc alloys from our earlier results. The Al-1%Sc alloy rolled at 473K and 230K showed two stages of hardening due to onset of dynamic recovery/recryztallisation process at ~0.5 and 1.5 strain respectively. The presence of large amounts of Al3Sc precipitates are not effective in pinning the mobile dislocations beyond 0.5/1.5 strain as the applied stress on the dislocations makes them capable of detaching away from the precipitate that has nucleated heterogeneously on it. Large scale non-homogeneous precipitate dislocation interactions led to the reduction in storage mechanism through annihilation of dislocations and disintegration of sub boundaries