高硅铝合金高温微观力学行为研究

Study of Micromechanical Behavior of High-Silicon Aluminum Alloys at Elevated Temperatures

高硅铝合金以其优异的性能在电子封装领域具有广阔的应用前景,准确地测量其高温微观力学行为具有重要意义.本文基于数字图像相关(DIC)方法,对Al-27%Si、Al-42%Si、Al-60%Si 3种不同硅含量高硅铝合金的拉伸试样开展了扫描电子显微镜(SEM)下的高温原位拉伸实验研究.分析了在20~300℃下测得的3种合金的应力-应变曲线、微尺度全场应变分布规律以及拉伸试样的断口形貌.结果表明,硅的含量和温度对高硅铝合金拉伸力学行为具有显著的影响.随着温度的升高,3种合金的应变量均逐渐增大,其中Al-27%Si的应变量变化最大.3种合金的抗拉强度随温度的升高均近似呈线性趋势降低,常温下Al-27%Si最高,200℃以上时Al-42%Si最高,Al-60%Si合金的抗拉强度最低.在Al-27%Si与Al-42%Si合金的应变场中的铝基体相内部出现了明显的应变集中现象,而Al-60%Si的应变分布较均匀.温度对3种合金的微尺度拉伸变形场分布规律影响不大.合金的拉伸断口形貌表明,随着硅含量的增加,高硅铝合金主要的拉伸断裂机制由铝相的韧性断裂逐渐转变为硅相的脆性断裂,而温度对其影响较小.3种高硅铝合金在不同温度下拉伸时均无明显的屈服现象,也未出现颈缩现象.

High-silicon aluminum alloys have broad application prospects in the field of electronic packaging owing to their excellent performance,warranting accurate measurement of their high-temperature micromechanical behavior.In this paper,based on digital image correlation(DIC)methods,high-temperature in situ tensile test stud-ies were conducted under a scanning electron microscope(SEM)on high-silicon aluminum alloys with three different levels of silicon content,including Al-27%Si,Al-42%Si,and Al-60%Si.The stress-strain curves,microscale fullfield strain distribution,and fracture morphology of the three alloys,measured in the range of 20—300℃,were analyzed.Results showed that silicon content and temperature had a significant effect on the tensile mechanical behavior of the three alloys.With increasing temperature,the strains in the three alloys gradually increased,with maximum strain change in Al-27%Si.The tensile strength of the three alloys decreased linearly with increasing temperature.The tensile strength of Al-27%Si was highest at normal temperature,that of Al-42%Si was highest at temperatures>200℃,and that of Al-60%Si alloy was the lowest.The strain concentrations of the aluminum matrix phase in the strain fields of Al-27%Si and Al-42%Si alloys were obvious,and the strain distribution of Al-60%Si was relatively uniform.Temperature had little effect on the distribution law of the microscale tensile deformation field of the three alloys.Their tensile fracture morphologies showed that the fracture mechanism of the high-silicon aluminum alloy gradually changed from the ductile fracture of the aluminum phase to the brittle fracture of the silicon phase with increasing silicon content,with temperature having little effect.The three aluminum-silicon alloy samples showed no obvious yielding phenomena and no necking phenomena when stretched at different temperatures.