Change of solidification behaviors in the superheating Sn-40wt.%Bi alloy from the viewpoint of the relaxation of properties

Abstract

The effects of melt overheating treatment on solidification of Sn-Bi alloys are studied from the viewpoint of the relaxation of properties. The results reveal that the change trends of cooling rate, undercooling degree of the primary and eutectic nucleation and maximum solidification rates of primary phase of melts not undergoing the relaxation are contrary to those of melts undergoing the relaxation. However, the change of these parameters could not explain the change on the microstructures. The present paper suggests the increasing of the apparent primary undercooling during solidification can be used to describe the refinement of primary phase after melts undergoing the relaxation. Our study may open new possibilities for the control of solidification process, which governs the microstructure, mechanical and physical properties of solids.K e y w o r d s : structural relaxation, alloys, crystal growth