【摘要】 采用水冷铜模浇注不同Mg含量的Al-Si合金试样,通过室温拉伸、激光散射法测试合金试样力学性能和热传导性能,结合OM/SEM结果分析Mg元素含量对Al-Si合金铸态组织结构和性能的影响规律。结果表明:Al-8.5Si-xMg合金铸态组织由初生α-Al和共晶Si组成,当Mg元素含量提高至0.4wt%～0.71wt%范围时,共晶硅的平均长度从68μm左右降低到61μm左右;共晶Si相组织均匀性得到提升,这种Si相的组织结构有利于自由电子在初生α-Al和共晶Si之间自由运动,合金热导率下降幅度趋于平缓。在较快冷却速率条件下,Mg元素在Al基体中固溶度比平衡凝固高,提高了初生α-Al的强度。更多还原

【Abstract】 Al-Si alloy specimens with different amounts of Mg were achieved by water-cooled copper mould casting. The mechanical properties and thermal conductivity of the alloy specimens were tested respectively by room temperature tensile test and LAF laser thermal diffusivity measurement. Effect of Mg content on the as-cast structure and properties of Al-Si alloy was analyzed according to OM/SEM results. The results show that ascast microstructures of Al-8.5Si-xMg alloy were composed of primary Al and eutectic Si. When the content of Mg increased to 0.4 wt.%-0.71 wt.%, the average length of eutectic silicon decreased from 68 μm to 61 μm which enhanced the movement ability of free electrons between primary Al and eutectic Si and inhibited the rapid decrease of thermal conductivity in Al-Si alloy. Super saturated solid solution was formed by solid solution of Mg element into Al matrix under the rapid-cooling solidification and the strength of Al-Si alloys increased with solid solution of Mg element.更多还原