Dependence of Liquid Supercooling on Liquid Overheating Levels of Al Small Particles

Qingsong Mei; Juying Li

doi:10.3390/ma9010007

Dependence of Liquid Supercooling on Liquid Overheating Levels of Al Small Particles

Materials (Basel). 2015 Dec 24;9(1):7. doi: 10.3390/ma9010007.

Authors

Qingsong Mei¹, Juying Li²

Affiliations

¹ Department of Materials Engineering, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China. qsmei@whu.edu.cn.
² School of Mechanical Engineering, Wuhan Polytechnic University, Wuhan 430023, China. jyli@whpu.edu.cn.

Abstract

The liquid thermal history effect on liquid supercooling behavior has been found in various metals and alloys; typically the degree of liquid supercooling (ΔT^-) increases with the increase of liquid overheating (ΔT⁺) up to several to tens of degrees above the equilibrium melting point (T₀). Here we report quantitative experimental measurements on the ΔT^--ΔT⁺ relationship of Al small particles encapsulated in Al₂O₃ shells by using a differential scanning calorimeter. We find a remarkable dependence of ΔT^- on ΔT⁺ of Al small particles, extending to at least 340 °C above T₀ of Al (~1.36T₀), which indicates the existence of temperature-dependent crystallization centers in liquid Al up to very high liquid overheating levels. Our results demonstrate quantitatively the significant effect of liquid thermal history on the supercooling behavior of Al and its alloys, and raise new considerations about the dependence of ΔT^- on ΔT⁺ at very high ΔT⁺ levels.

Keywords: Al particles; liquid overheating; liquid supercooling; solidification; thermal history.