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采用低压铸造工艺制备了Mg-10Gd-3Y-0.7Zr合金,利用OM、SEM、EDS、DTA等手段研究了合金在热处理前、后的微观组织演变,并对其热处理工艺进行优化,以提高合金的综合力学性能,并结合组织变化分析了合金的热处理强化机制。结果表明,Mg-10Gd-3Y-0.7Zr合金的铸态组织主要由α-Mg初生相和Mg24(Gd,Y)5共晶相组成,且Mg24(Gd,Y)5共晶相呈网状分布在晶界上。热处理后,连续分布的Mg24(Gd,Y)5相消失,主要为α-Mg和颗粒状Mg5(Gd,Y)相。在520℃×14h+230℃×20h热处理效果最佳。经过520℃固溶14h后,合金强度变化不大,但是伸长率由5.5%变为13.4%,提高了144%。230℃时效处理后,合金的综合力学性能优异,抗拉强度和屈服强度达到307.8 MPa和200.4 MPa,伸长率为7.2%,较热处理前分别提高了41%、38%和31%。
Mg-10Gd-3Y-0.7Zr alloy was prepared by low-pressure casting process. The microstructure evolution of the alloy before and after heat treatment was studied by means of OM, SEM, EDS and DTA. The heat treatment process was optimized to improve the alloy The mechanical properties of the alloy were analyzed. The heat treatment strengthening mechanism of the alloy was analyzed with the change of the structure. The results show that the as-cast microstructure of Mg-10Gd-3Y-0.7Zr alloy mainly consists of α-Mg primary phase and Mg24 (Gd, Y) 5 eutectic phase, and Mg24 (Gd, Y) Distribution in the grain boundary. After heat treatment, the continuous distribution of Mg24 (Gd, Y) 5 phase disappears, mainly α-Mg and granular Mg5 (Gd, Y) phase. At 520 ℃ × 14h + 230 ℃ × 20h heat treatment best. After 520 ℃ solution for 14h, the strength of alloy did not change much, but the elongation changed from 5.5% to 13.4%, increased by 144%. After aging at 230 ℃, the mechanical properties of the alloy were excellent. The tensile strength and yield strength reached 307.8 MPa and 200.4 MPa, respectively. The elongation was 7.2%, which was increased by 41%, 38% and 31% respectively before heat treatment.