A new mode of the discontinuous dissolution reaction in Mg-10 wt.% Al alloy

The occurrence of discontinuous precipitation (DP) and dissolution reaction s has been investigated in Mg-10 wt.% Al alloy. The application of a specia l cyclic heat treatment allowed to observe a new mode of the discontinuous dissolution reaction. The reaction starts preferably and occurs faster at t he original locations of the grain boundaries, which is in contrast to the commonly observed behaviour where the reaction occurs, in the early stage, primarily at the reaction front of the former DP colonies. The proposed exp lanation is attributed to a characteristic movement of the reaction front o f the DP colony away from and back to the original location of the grain bo undary during subsequent cycles of ageing and dissolution. (C) 2001 Elsevie r Science B.V. All rights reserved.