On melt concentration at the solid/liquid interface during preparation of directionally solidified Sn–36 at.%Ni peritectic alloy

•Variation of melt concentration with thermal stabilization time is predicted.•Remelting of the solid phase is taken into consideration.•Solubilities of intermetallic phases are taken into consideration.

Experiments consisting of melting followed by thermal stabilization ranging from 0 to 6 h on Sn–36 at.%Ni peritectic alloy have been carried out in Bridgman-type furnace. Both primary Ni3Sn2 and peritectic Ni3Sn4 phases are intermetallic phases with narrow solubility in this peritectic alloy. A mushy zone is formed between the complete liquid zone and the non-molten zone due to imposed temperature gradient. The transport of atoms due to this temperature gradient cause extensive variations in both microstructure and melt concentration at the solid/liquid interface. Microstructure evolution and solute concentration field in the liquid at the mushy zone/liquid interface have been characterized. An analytical model is proposed to describe the melt concentration at the mushy zone/liquid interface in peritectic alloys during thermal stabilization. When both the remelting of primary α phase and solubilities of primary and peritectic phases are taken into consideration, the calculations show reasonable agreement with experimental results.