铸态Mg-4Al-4Si-0.75Sb合金的显微组织与力学性能

摘要

Mg-4Al-4Si-0. 75Sb (AS44-0. 75Sb)(mass fraction/%) magnesium alloys were prepared by the gravity casting. Microstructure and mechanical properties at room temperature of the as-cast AS44-0. 75Sb alloy were investigated. The results show that the as-cast microstructure consists of α-Mg matrix, β-Mg17 Al12 phase, Mg2Si phase and Mg3Sb2 phase; the addition Sb of 0. 75 results in the formation of Mg3 Sb2 phase with high melting-point, the morphology of skeleton-like primary Mg2 Si phase can be modified significantly and becomes refinement Chinese script Mg2Si. The hardness HV of alloy is 65. 9, yield strength, ultimate tensile strength and extension percentage are about 136. 4MPa, 172. 3MPa and 3. 3% respectively. The fracture forms of the alloy is quasi-cleavage brittle fracture.%采用重力铸造法制备Mg-4Al-4Si-0.75Sb(AS44-0.75Sb)(质量分数/％,下同)镁合金,研究铸态合金的显微组织和室温力学性能.结果表明:铸态AS44-0.75Sb合金主要由α-Mg基体、β-Mg17Al12相、Mg2Si相和Mg3Sb2相组成；加入0.75Sb后形成高熔点的Mg3Sbz相,显著改善了Mg2Si相的形貌,使粗大的骨骼状Mg2Si转变为相对细小的汉字状Mg2Si.铸态合金的硬度HV为65.9,屈服强度为136.4MPa,抗拉强度为172.3MPa,伸长率为3.3％；拉伸断裂形式为准解理脆性断裂.