【摘要】 采用压铸工艺制备了SA42和Mg-4Sm-2.6Al （SA42.6）合金，分析了微量Al含量变化对合金力学性能的影响。结果表明，在SA42合金的基础上添加0.6%（质量分数，下同）的Al后，合金屈服强度和伸长率分别降低了10.2%和63.5%。这是因为Al与基体内固溶的Sm反应形成了大量的大块Al₂Sm相，使得合金基体内固溶的Sm浓度降低了近50%，导致固溶强化效果大幅降低。形成的Al₂Sm相带来的第二相强化和晶界强化效果无法弥补固溶强化效果的缺失，导致了SA42.6合金的屈服强度比SA42合金的低了近20MPa。伸长率大幅降低主要归因于Al₂Sm颗粒与基体的模量不匹配，Al₂Sm颗粒较脆较硬，在变形过程中产生了较大的应力集中，加速了合金的断裂失效。更多还原

【Abstract】 SA42 and Mg-4Sm-2.6Al（SA42.6） alloys were fabricated by HPDC process, and influence of trace Al content on mechanical properties was systematically analyzed. The results indicate that with 0.6% Al addition to SA42 alloy, the yield strength and elongation are reduced by 10.2% and 63.5%, respectively, which is attributed to the large quantities of massive Al₂Sm phases generated by reaction between Al and Sm dissolved into the matrix, leading to an approximate 50% reduction in Sm concentration within Mg matrix, significantly diminishing solute strengthening effects. The contributions from secondary phase strengthening as well as grain boundary strengthening provided by formed Al₂Sm can hardly compensate for the loss in solid solution strengthening effect, resulting in an approximate reduction of 20 MPa in yield strength for SA42.6 compared to that of SA42. The substantial decrease in elongation primarily arises from modulus mismatch between Al₂Sm particles and Mg matrix. The brittle and hard Al₂Sm particles induce great stress concentrations during deformation processes, thereby accelerating fracture and failure.更多还原