Computational modelling of heat⧹mass transfer near the LIQUID–SOLID interface during rapid solidification of binary metal alloys under laser treatment

Abstract

This paper presents the results of an investigation into the problem of planar solid–liquid interface stability during rapid solidification of binary metal alloys under laser treatment. A new quantitative model is proposed. This model describes the self-organized development of stable spatially-periodic vortices in the melt near the solid–liquid interface due to concentration- (or thermal) capillary effects fn2 fn2 The basic idea of the feasibility of thermal-capillary convection at the liquid–solid interface belongs to Dr G. L. Tsarev (Physical-Technical Institute, Minsk, Belarus). together with effects due to the influence of normal concentration or temperature gradients directed from the interface towards the melt. These vortices give rise to a cellular structure at the solid–liquid interface of rapidly frozen melts. A computer code was developed to solve the set of second-order linear differential equations which describe heat and mass transfer at the liquid–solid interface. This model allows calculation of the liquid phase velocity field, the second component concentration field in the melt, as well as the temperature field in the liquid and solid phases near the solid–liquid interface at a given solidification rate.