采用选区激光熔化(selective laser melting, SLM)技术制备 Mg-3.4Y-3.6Sm-2.6Zn-0.8Zr 合金，系统探究固溶及时效热处理工艺对其显微组织与力学性能的影响。 通过优化 SLM 工艺参数(激光功率 60 W，扫描速度 300 mm/s，层厚 20 μm)，结合固溶热处理(500 ℃×12 h)和时效处理(225 ℃×0~50 h)，利用 SEM、TEM、XRD 等手 段 分 析 显 微 组 织 演变 ，并测 试 压 缩 性 能 及 硬 度 。 结果 表 明 ，时效 处 理 40 h 后 ，合金 硬 度 达 峰 值 93.9 HV，晶内 析 出 纳 米 级 β′相(尺寸 约7nm×3nm)，晶界处形成 Mg24Y5 和少量 Mg41Sm5 混合相，同时生成层状 Mg12(Y, Sm)Zn(14H-LPSO 结构)。 相较于固溶态 ，时效 后 屈 服 强 度 与 抗 压 强 度 分 别 下 降 11.3%(338 MPa)和 11.2%(469 MPa)，但压 缩 应 变 提 升 5%(21.4%)，归因 于LPSO 相的非均匀变形机制。 研究揭示了 SLM 稀土镁合金的强化机理以相变强化为主，晶界粗大析出相导致力学性能恶化，而 LPSO 相显著改善塑性。

AMg-3.4Y-3.6Sm-2.6Zn-0.8Zr alloy was fabricated via selective laser melting (SLM), and the effects of solution and aging heat treatments on its microstructure and mechanical properties were systematically investigated. The SLM processing parameters were optimized (laser power: 60 W, scanning speed: 300 mm/s, layer thickness: 20 μm), followed by solution treatment (500 ℃ for 12 h) and aging treatment (225 ℃ for 0~50 h). The microstructural evolution was analysed via SEM, TEM, and XRD, and the compressive properties and hardness were evaluated. The results show that after 40 h of aging, the peak hardness of the alloy reaches 93.9 HV. Nanoscale β′ precipitates (~7 nm×3nm) form within the grains, whereas Mg24Y5 and a small amount of Mg41Sm5 phases are observed at the grain boundaries, along with the formation of layered Mg12(Y, Sm)Zn (14H-LPSO structure). Compared with those in the solution-treated state, the yield strength and compressive strength of the aged alloy decrease by 11.3% (338 MPa) and 11.2% (469 MPa), respectively, whereas the compressive strain increases by 5%(21.4%). This improvement in plasticity is attributed to the heterogeneous deformation mechanism of the LPSO phase. The study reveals that the strengthening mechanism of the SLM-processed rare-earth magnesium alloy is primarily phase transformation strengthening, whereas the coarsened grain boundary precipitates lead to deterioration of the mechanical properties. In contrast, the LPSO phase significantly enhances plasticity.