(1. 广州有色金属研究院，广州 510650；
2. 中南大学材料科学与工程学院，长沙 410083)
摘 要: 利用光学显微镜、扫描电子显微镜和X射线衍射仪分析铸态和固溶态AZ91D-xSm(x=0~1)合金的组织和相组成，测试其室温拉伸力学性能和冲击韧性。结果表明：随着Sm含量的增加，铸态组织中不连续网状β-Mg17Al12相发生破碎，数量逐渐减少，而小块状高热稳定性新相Al2Sm数量逐渐增多；拉伸力学性能和冲击韧性整体均逐渐提高，AZ91D-0.88Sm合金的抗拉强度σb、伸长率δ和冲击韧性αnK分别达到230 MPa、15.5%和24 J/cm2；经固溶处理后，β-Mg17Al12相完全固溶于α-Mg基体中，只存在Al2Sm相；拉伸力学性能和冲击韧性均明显提高，但其提高幅度随着Sm含量的增加而有所减缓。
关键字: AZ91D合金；Sm变质；显微组织；拉伸力学性能；冲击韧性
（1. Guangzhou Research Institute of Non-ferrous Metals, Guangzhou 510650, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The microstructures and phase compositions of as-cast and solution-treatedAZ91D-xSm (x=0-1) alloys were investigated by optical microscopy, scanning electron microscopy andX-ray diffractometry. Meanwhile, the tensile mechanical property and impact toughness at ambient temperature were tested. The results show that the discontinuous networkβ-Mg17Al12phase breaks and decreases gradually among the as-cast microstructure with increasing the Sm content. Meanwhile, small block Al2Sm new phase with high thermal stabilityincreases gradually.The tensile mechanical property and impact toughness on the whole are enhanced gradually. Tensile strength σb, elongation δand impact toughness αnKof AZ91D-0.88Sm alloy reach230 MPa, 15.5% and 24 J/cm2, respectively. After solution treatment, β-Mg17Al12phase dissolves into α-Mg matrix completely and Al2Sm phase still exists. The tensile mechanical property and impact toughness are enhanced obviously and the improving amplitude decreases slightly with increasing the Sm content.
Key words: AZ91D alloy; Sm modification; microstructure; tensile mechanical property; impact toughness
