CALCULATION OF PRECIPITATE DISSOLUTION ZONE KINETICS IN OXIDIZING BINARY 2-PHASE ALLOYS

Oxidation of a binary alloy at appropriate oxygen potentials leads to the selective oxidation of one component. When that component is conce ntrated in a dispersed precipitate within a two-phase alloy, dissoluti on of the precipitate phase will occur when external oxidation takes p lace. In this paper a diffusional analysis is used to predict the widt h of the precipitate-dissolution zone (X(d)) formed during such an oxi dation process. Solutions to the case of both a stationary and a mobil e alloy/scale interface are obtained. The predicted values of X(d) der ived from both the present and previous theoretical treatments are the n compared with recently obtained experimental results on the oxidatio n behaviour of a Ni-Ni3Si alloy. Predicted values of X(d) calculated u sing the present model were in very close agreement with those obtaine d experimentally. This is in contrast to the values predicted from pre viously derived models, which significantly underestimated X(d). Copyr ight (C) 1996 Acta Metallurgica Inc.