Local melting/solidification during peritectic solidification in a steep temperature gradient: analysis of a directionally solidified Al–25at%Ni

Abstract

Melting of primary Al3Ni2 phase and solidification of Al3Ni peritectic phase during directional solidification of an Al–25at%Ni peritectic alloy have been investigated. In a steep temperature gradient of up to 50 K/mm and at a pulling rate of 20 μm/s, an incomplete coverage of peritectic Al3Ni phase on the surface of the primary Al3Ni2 phase has been observed. Below the peritectic temperature in the presence of the incomplete coverage, melting of primary Al3Ni2 on the one side and solidification to the Al3Ni peritectic phase on the other side proceed swiftly via diffusion through the interphase liquid layer. Theoretical calculations based on an incomplete-coverage-related melting/solidification model are in close agreement with the experimental measurements.