Computer simulated dissolution of carbide precipitates in alloys

Abstract

Conventional theory on the dissolution of a spherical particle of a second phase in an alloy is shown to be inappropriate when considering carbide species. In particular, the assumptions of an error function solute concentration profile and a constant equilibrium solute concentration level at the interface cannot be made. A model for computer simulated dissolution is therefore proposed which is based on the diffusion of solute away from a carbide particle across discrete shell increments. The method is used to predict times for complete and partial dissolutions of M₂₃C₆ particles in Nimonic 80A (registered trade mark of Henry Wiggin and Co. Ltd). As a result, the effect of solution heat treatment of the alloy is more clearly understood and practical improvements are recommended.