定向凝固速度对Mg-wt%Ag-Zn合金导热率的影响

Effect of the Directional Solidified Velocities on Thermal Conductivity of Mg-wt%Ag-Zn alloys

摘要:

制备铸态Mg-1Ag-Zn, Mg-3Ag-Zn 和 Mg-5Ag-Zn合金试样，并计算其导热率。随着Ag含量的增加，铸态合金试样的导热率减少。再将其铸态合金的试样以三种不同的定向凝固速率（v=25μm/s, v=50μm/s, v=75μm/s）制备成定向凝固试样，计算其定向凝固试样的导热率。结果显示：随着定向凝固速率的增加，合金的导热率降低。合金中溶质元素的含量与定向凝固速率是影响导热率的重要因素，这两个因素可以增强电子和声子的散射过程，减少自由行程，最终降低合金的导热率。

关键词:Mg合金;Ag含量;定向凝固;热导率

Abstract:

Specimens of as-cast Mg-1Ag-Zn, Mg-3Ag-Zn and Mg-5Ag-Zn alloys were fabricated, and then the specimens’ thermal conductivity was calculated. With the increase of Ag content, the thermal conductivity decreased significantly of as-cast alloys. After that, directional solidified specimens of the above mentioned as-cast Mg-Ag-Zn alloys were made at three different pulling velocities: V=25μm/s, V=50μm/s, V=75μm/s, and then again calculated their thermal conductivity. The result showed that with the increase of the pulling velocity, the thermal conductivity of alloys decreased significantly. Variations in the solute content and the pulling velocities are believed to play important roles on the thermal conductivity of Mg- Ag-Zn alloys. Since those two circumstances can strengthen the electron’s scattering process, reduce their free path, and thereby reduce the alloys’ thermal conductivity.

Key words:Mg alloy; Ag content; directional solidified; thermal conductivity