Abstract
The Mg–Si alloys have low CTEs (coefficients of thermal expansion) and other merits, which contribute to their application potential in the electronic industry. However, the details of their thermal properties are still unclarified, and need more research. In this study, the thermal conductivities (TC) of Mg–xSi (x = 1 wt.%, 1.38 wt.%, 2 wt.%, 3 wt.%, and 4 wt.%) binary alloys and Mg–4Si–yCa (y = 0.2 wt.%, 0.4 wt.%, 0.6 wt.%, 0.8 wt.%, and 1.0 wt.%) alloys over the temperature range of 25–300 °C were systematically studied. The results show that the TC of Mg–xSi binary alloys decreases with the increase of Si content, while it increases slightly near the eutectic composition. The addition of a Ca element to Mg–4Si alloys has an obvious modification effect on the Mg2Si phase. When the Ca content increases constantly, the TC of the alloys decreases at first; then, there is a significant increase at the content of 0.8 wt.% Ca, and after that, it continues to decline. The mechanism is mainly related to the precipitation of the CaMgSi phase at 0.8 wt.% Ca content.
Highlights
As a new type of green structural material, magnesium alloys have wide applications because of their superior properties
The thermal conductivity (TC) of pure magnesium is 157 W/(m·K) at room temperature, which is lower than copper and aluminum, but the magnesium alloy has the advantage of light weight; the TC is larger per unit mass [4]
The magnesium alloy has a significant decrease in TC after adding common alloying elements
Summary
As a new type of green structural material, magnesium alloys have wide applications because of their superior properties. There are a lot of research studies about the mechanical properties of magnesium alloys at present [1,2,3]. As the Zn or Al content increases, the volume of the precipitated second phase and the amount of the solid solution atom increase This enhances the scattering of electrons and phonons, leading to a decrease in the TC of these alloys. Studies on the TC of Mg alloys focus mostly on Mg–Zn [10,11], Mg–Al [12,13], and Mg–Sn [14,15] alloy systems, while there is almost no study on the thermal properties of Mg–Si alloys in which the precipitation of Mg2 Si can effectively lower the CTE compared with pure magnesium. In the present study, it is necessary to investigate the effects of the addition of modification elements on the TC behavior, such as the addition of Ca
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