Orientation selection of particles growing in an alloy melt

Abstract

The dynamics of orientation selection of a particle in an alloy melt is studied by using the method of multiple scales. The dynamic model accounts for two sources of anisotropic interfacial energy, which is characterized by two anisotropy parameters ε1 and ε2. The anisotropy parameters and the initial concentration are systematically changed to investigate the continuous orientation variations of the growing particle. In the <100> directions, as the anisotropy parameter ε1 increases, the interface temperature and concentration gradient increase, and the interface of the particle accelerates its growth and becomes locally convex, whereas in the <110> directions, the interface temperature and concentration gradient decrease, and the interface decelerates its growth and becomes locally concave. During this growth process, the particle changes continuously its preferred growth direction from <110> to <100>. As negative ε2 increases, a reversed process occurs that the particle changes continuously its preferred growth direction from <100> to <110>. In the preferred growth direction, the initial concentration inhibits the growth of the particle, whereas in other growth directions the initial concentration facilitates the growth of the particle. The orientation selection of the particle displays the rich interface morphologies of the particle with deformed petal-shaped patterns.