Thermal Conductivity of As-Cast and Annealed Mg-RE Binary Alloys

Huiyun Guo,Mingqiang Chu,Yong Du,Shuhong Liu,Deqing Wang,Lei Huang

doi:10.3390/met11040554

Abstract

Thermal conductivity and phase identification of Mg-RE (Rare-Earth) alloy (Mg-La, Mg-Ce, Mg-Nd, Mg-Sm) in both as-cast and annealed states were investigated. The thermal conductivity was measured by the laser flash method in the composition range of 4 wt.% to 12 wt.% RE and the temperature range of 298 K to 673 K. Results demonstrated that homogenization treatment can increase its thermal conductivity. The thermal conductivity increases with the increasing temperature in two states, which is inconsistent with the pure magnesium, and the thermal conductivity of Mg-RE alloys decreases with the alloy additions. Compared with the atomic radius, valence, and intermetallic compounds, the solid solubility of the above four RE elements in α-Mg plays a vital role in the thermal conductivity of Mg-RE binary alloy. The reduction of thermal conductivity caused by the addition of Nd and Sm, which show observable solid solubility in α-Mg, is significantly greater than the addition of La and Ce with negligible solid solubility in α-Mg.

Highlights

Thermal conductivity is affected by solid solution atoms, second phases, temperature changes, and heat treatment [7,8,9,10,11,12]
Pan et al [13] found that the influence on thermal conductivity of magnesium alloys for the six solute elements was Zn < Al < Ca < Sn < Mn < Zr
One piece was directly used for as-cast research, and the other piece was sealed in an evacuated silica capsule under vacuum (1 Pa) to wait for subsequent homogenization heat treatment

Summary

Introduction

Compared with the atomic radius, valence, and intermetallic compounds, the solid solubility of the above four RE elements in α-Mg plays a vital role in the thermal conductivity of Mg-RE binary alloy. Thermal conductivity is an important thermophysical properties, and it plays an essential role in the performance of alloy. High thermal conductivity of magnesium alloys provides fast heat conduction. It ensures that the temperature is evenly distributed, improving fatigue property and prolonging the service life [4,5,6]. Thermal conductivity is affected by solid solution atoms, second phases, temperature changes, and heat treatment [7,8,9,10,11,12].

Methods

Results

Conclusion