Preparation of the initial solid–liquid interface and melt in directional solidification of Al–18 at%Ni peritectic alloy

Abstract

The preparation of the initial solid–liquid interface and melt is a critical step in directional solidification process. Experiments on Al–18 at%Ni peritectic alloy consisting of melting followed by thermal stabilization ranging from 0 to 2 h were carried out in a Bridgman-type furnace. In the directional melting process, due to the temperature gradient imposed on the rod, a mushy zone was created between the complete liquid zone and non-molten solid zone parallel to the temperature gradient. With the thermal stabilization time increase, the volume fraction of the liquid inclusions in the mushy zone decreased. After 2 h of thermal stabilization, the initial solid–liquid interface was corrugated, and the Ni concentration in the complete liquid melt zone was uniform but below the original composition. A solute diffusion transport model in a temperature gradient was proposed to describe the concentration evolution both in the mushy zone and the complete liquid melt zone during thermal stabilization.