Sr对Mg-5Al-0.8Ca-0.2La镁合金显微组织及高温性能的影响

Effects of Sr on the Microstructure and Mechanical Properties at Elevated Temperature of Mg-5Al-0.8Ca-0.2La Magnesium Alloy

研究了Sr对Mg-5Al-0.8Ca-0.2La镁合金显微组织与室温和高温力学性能的影响。实验结果表明,Sr的加入显著细化了基体合金的显微组织,抑制了-βMg17Al12相的析出;并且在晶界上析出了Mg-Al-Sr,Al2Ca和Al11La3耐热相,提高了晶界的高温稳定性。Sr的加入虽然导致合金的室温抗拉强度和延伸率下降,但提高了合金高温抗拉强度,也略提高了室温和高温屈服强度。

The effects of Sr on microstructure, mechanical properties at ambient and elevated temperatures of Mg-5Al-0.8Ca-0.2La magnesium alloy were studied. The results show that the a-Mg matrix is refined with the addition of Sr, the β-Mg17Al12 phase is restrained,and few heat-resistant phases are precipitated at the grain boundary（Mg-Al-Sr, Al2Ca and Al11 La3 ）, which improves the stability of the grain boundary at elevated temperature. Though the addition of Sr into the alloy decreases the tensile strength and elongation at ambient temperature, the tensile strength at elevated temperature is improved remarkably. The yield strength at both ambient and elevated temperature also increase a bit.