Guan Sheng, Wang Pengyue, Wang Tianhua, Wang Chenggang, Liu Guojun, Zhu Yongfu
Key Laboratory of Automobile Materials, Ministry of Education, School of Materials Science and Engineering, Jilin University, 5988# Renmin Street, Changchun 130025, China.
FAW Foundry Co., Ltd., Crossing of Hexie Street & Bingwu Road, Changchun 130013, China.
Materials (Basel). 2025 Jan 8;18(2):231. doi: 10.3390/ma18020231.
With the increasing demand for magnesium (Mg) alloys with high strength and good ductility, this study explores high-pressure die-cast (HPDC) Mg-6Al-2RE (AE62), Mg-8Al-2RE (AE82) and Mg-8Al-2RE-0.2Ca (AEX820) alloys (wt. %). Their microstructures and mechanical properties are investigated under both as-cast and T5-aged (direct artificial aging after casting) conditions. HPDC alloys consist of outer fine-grain regions and inner coarse α-Mg grains with abundant eutectic phases. The increasing addition of Al has an insignificant effect on the refinement of the grain size of α-Mg, but it significantly influences the morphology and area fraction of the second phases. The average grain sizes of α-Mg in HPDC AE62, AE82 and AEX820 alloys are approximately 4.0 μm, 3.9 μm and 3.7 μm in the edge regions and about 13.9 μm, 12.8 μm and 12.1 μm in the core regions, respectively. When aged at 200 °C, β-MgAl precipitates are predominantly formed in the studied alloys. Increasing the Al and Ca concentrations effectively refines the microstructures and enhances the aging hardening response and the strength, albeit at the expense of considerably reduced ductility. The peak-aged AE62 alloys demonstrate balanced tensile properties, with ultimate tensile strength (UTS), yield strength (YS), and elongation at fracture (E) at room temperature of ~241 MPa, ~141 MPa and ~7.1%, respectively, and values of ~129 MPa, ~96 MPa and ~19.8%, respectively, at 175 °C. Compared to peak-aged AE62 alloy, the UTS and YS of peak-aged AEX820 alloys are improved by ~6.7% and ~14.2%, respectively, at RT and ~8.5% and ~12.5% at 175 °C, while E is decreased by 35.2% at RT and 33.3% at 175 °C, primarily due to the high area fraction of secondary phases.
随着对具有高强度和良好延展性的镁（Mg）合金需求的不断增加，本研究探索了高压压铸（HPDC）的Mg-6Al-2RE（AE62）、Mg-8Al-2RE（AE82）和Mg-8Al-2RE-0.2Ca（AEX820）合金（重量百分比）。研究了它们在铸态和T5时效（铸造后直接人工时效）条件下的微观结构和力学性能。HPDC合金由外部细晶区和内部粗大的α-Mg晶粒以及丰富的共晶相组成。Al添加量的增加对α-Mg晶粒尺寸的细化影响不显著，但对第二相的形态和面积分数有显著影响。HPDC AE62、AE82和AEX820合金中α-Mg的平均晶粒尺寸在边缘区域分别约为4.0μm、3.9μm和3.7μm，在核心区域分别约为13.9μm、12.8μm和12.1μm。在200°C时效时，所研究的合金中主要形成β-MgAl析出相。增加Al和Ca的浓度有效地细化了微观结构，增强了时效硬化响应和强度，尽管以显著降低延展性为代价。峰值时效的AE62合金表现出平衡的拉伸性能，室温下的极限抗拉强度（UTS）、屈服强度（YS）和断裂伸长率（E）分别约为241MPa、141MPa和7.1%，在175°C时分别约为129MPa、96MPa和19.8%。与峰值时效的AE62合金相比，峰值时效的AEX820合金在室温下的UTS和YS分别提高了约6.7%和14.2%，在175°C时分别提高了约8.5%和12.5%，而E在室温下降低了35.2%，在175°C时降低了33.3%，主要是由于第二相的高面积分数。
