DIRECTIONAL SOLIDIFICATION OF METAL MATRIX PARTICULATE COMPOSITE MATERIALS

摘要

Metal matrix paniculate composites (MMPCs) are made of a continuous metallic matrix and discontinuous reinforcing particles. An efficient solidification model for MMPCs is developed in this paper. The molten metal is considered as a continuous multi-component medium, while the particles are treated as a discrete Lagrangian entity that exchanges mass, momentum and energy with the melt. The particle entrapment model is developed to determine the possibility of the particles to interact with the interface. The forces acting on particles in front of an advancing solidification interface are quantified for particle engulfment and pushing (PEP), and this model is incorporated into the computational scheme for simulating particle dynamic distributions. The integrated numerical model is applied to Al alloy growth with ZrO_2 particle inclusions in the directional solidification. The results show that particle movement and distribution are greatly affected by the two-phase liquid flow pattern and intensity. The effect of particle size and solidification velocity on PEP and final particle distribution in the solid matrix are also determined.