镁及其合金导热研究进展

Recent Progress on Thermal Conductivity of Magnesium and Its Alloys

本文简要回顾了国内外镁合金导热行为和导热机制的研究工作,梳理了影响镁合金导热的因素,如固溶原子、变形和温度等。在此基础上,归纳总结了高导热镁合金的发展,并讨论了导热与力学性能之间的倒置关系,最后提出高导热镁合金的设计思路和发展方向。主要结论如下:固溶原子会导致晶格畸变而降低镁合金热导率,与其化合价、原子半径和原子核额外电子有关;第二相与Mg基体的界面会对电子运动产生阻碍作用,进而削弱热导性能,具体与其形貌、尺寸、分布和含量相关;对于变形镁合金,沿径向或法向方向的导热性能往往优于挤压或轧制方向;温度是影响镁合金热导率的重要因素,在不同的温度区间内,热导率的主要散射机制不同,一般需要对各温度区间分开讨论。未来关于导热镁合金的研究仍有必要继续深入,可以重点聚焦于以下方面:镁合金显微组织与其导热性能的关系量化;多元镁合金的导热行为及其导热模型的建立;高导热镁合金成分设计与组织控制;镁合金导热行为的物理本质探究。

This article reviews recent progress on the thermal conductivity of magnesium and its alloys. First, lattice distortion induced by solute atoms negatively impacts the thermal conductivity of Mg alloys, which is correlated to three properties of solute atoms: atomic radius, chemical valency, and extranuclear electrons. Second, the formation of intermetallic compounds, which is accompanied by the creation of new phase interfaces that act as barriers to the movement of electrons, negatively impacts the thermal conductivity of Mg alloys. This negative effect is correlated to the morphology, size, distribution,and content of secondary phases. Thermal conductivity along the transverse or normal direction is superior to that along the extrusion or rolling direction for wrought Mg alloys with basal texture. Further, temperature significantly influences the thermal conductivity of Mg alloys;however, the underlying mechanisms vary depending on the temperature range and should be discussed separately. These aspects of research on Mg alloys with high thermal conductivity are still necessary in the future: quantifying the relationship between microstructure and thermal conductivity;thermal behavior of multicomponent Mg alloys and the establishment of its thermal conductivity model;compositional design and microstructural control of high thermal conductivity Mg alloys;physical nature of thermal behavior in Mg alloys.