Unveiling the interface between second phases and matrix on thermal conductivity of Mg alloys

Abstract

Solute atoms and second phases with low thermal conductivity are habitually regarded as the factors to the thermal conductivity of alloys. Nevertheless, the interface that is usually neglected can also be a noteworthy factor influencing the thermal conductivity of alloys due to its inherent nature of defects. The effect of interface on the thermal conductivity of alloys was quantitatively scrutinized in the binary Mg–La, Mg–Ce, Mg–Sm, Mg–Al, Mg–Zn, and Mg–Si alloys with concentration gradients. The effect of diverse excess second phases on the deterioration of thermal conductivity for Mg alloys followed this order: Mg2Si＞Mg17Al12＞Mg17La2＞Mg12Ce＞Mg41Sm5＞MgZn2. The quantitative total interfacial thermal resistance model for alloys was proposed, which was quantitatively understood by R=AGsρs3+BGsρs+CGs3ρs. The sequence of experimental data was conformed to that of the theoretical data acquired by this model. Alloying elements which second phases possess low shear modulus (G) and high density (ρ) were beneficial for the development of the low-thermal-resistance alloys. This rule can reinforce the theoretical basis for the thermal conduction of alloys. The data of the total interfacial thermal resistance was established preliminarily to instruct the design of low-thermal-resistance and high-thermal-conductivity Mg alloys.

Keywords

• Thermal conductivity
• Magnesium alloys
• Interface
• Second phases
• Thermal resistance