Mg对Al-22Si-10Ni合金组织和热学性能的影响

Effect of Mg on Microstructure and Thermal Properties of the Al-22Si-10Ni Alloy

Al-22Si-10Ni合金具有较高的导热性和较低的热膨胀特性,但硬度偏低,对其进行Mg合金化,研究Mg对该合金凝固组织和热学性能的影响。研究显示,Mg的加入主要影响合金的末期凝固进程,合金凝固末期反应由Al-Si-Al3Ni三元共晶反应向Al-Si-Mg2Si三元共晶反应转变;热处理促进Mg_(2)Si析出,少量Mg加入后Al-22Si-10Ni合金的热导率小幅上升,继续添加Mg后,热导率出现下降;Mg对合金热膨胀系数影响较小,可显著提升合金的硬度。Al-22Si-10Ni-0.5Mg合金表现出优异的综合性能,其室温热导率130.3 W/(m·K),25~100℃范围内平均热膨胀系数为13×10^(-6)/K,硬度达到HV144,性能较为接近喷射沉积制备的高含量Al-50Si合金,具有成为电子封装用材料的潜能。

Al-22Si-10Ni alloy possesses high thermal conductivity and low thermal expansion properties.However,its hardness is relatively low.In this paper,Mg element was added to study the effect on the solidification structure and thermal properties of the Al-22Si-10Ni alloy.The addition of Mg mainly affected the final solidification process of the alloy,which changed from Al-Si-Al3Ni ternary eutectic reaction to Al-Si-Mg_(2)Si ternary eutectic reaction.Heat treatment promoted the precipitation of Mg_(2)Si,and the thermal conductivity of Al-22Si-10Ni alloy increased slightly by adding small amount of Mg,then decreased gently as the content increased further.The addition of Mg could significantly improve the hardness while having little effect on the thermal expansion coefficient of the alloy.Al-22Si-10Ni-0.5Mg alloy exhibited excellent comprehensive properties.Thermal conductivity was 127.8 W/(m·K)at room temperature,the average thermal expansion-6 coefficient was about 13×10^(-6)/K at 25-100℃,and the HV hardness reached 144.The performance of Al-22Si-10Ni-0.5Mg was comparable to the current commercial Al-50Si alloys in the electronic packaging industry.