Sharp interface simulation of interaction of a growing dendrite with a stationary solid particle

Abstract

Numerical simulations are performed to study the response of a dendrite as it approaches a solid particle in the melt, such as may arise in metal-matrix composite solidification. A sharp interface, fixed grid numerical method is employed. A pure under-cooled melt is used to grow the dendrite. When the dendrite approaches the particle, appropriate interfacial conditions are specified at the particle-solid interface before and after contact. The behaviour of dendrites as they approach and grow around the particle is closely examined. For a particle to melt thermal conductivity ratio λ = k p k l < 1 corresponding to the situation for metal-matrix composites, for the parameters employed, the solidification front does not approach close enough to the particle to activate the particle pushing mechanism. Instead, the solidification front chooses to go around the particle, and eventually the particle is engulfed by sidebranches. Thus an entrapment mode of front-particle interaction is the likely outcome under dendritic growth conditions for λ < 1.