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

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 full-field 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. © 2020, Editorial Board of Journal of Tianjin University(Science and Technology). All right reserved.