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研究了不同添加量的混合稀土对压铸AZ91D合金的组织和力学性能的影响。添加混合稀土后,常温力学性能没有明显改善。在100℃时,混合稀土含量为0.4%的压铸AZ91D合金的力学性能与不含混合稀土的试样几乎相等。在170℃时,混合稀土含量为0.4%的压铸AZ91D合金的抗拉强度、屈服强度及伸长率分别为206MPa、142MPa、26%,比不含混合稀土的压铸AZ91D试样的力学性能分别提高15.7%、10%及30%。这是因为添加适量的混合稀土后,形成热稳定性较高的强化相,增加了位错滑移阻力并阻碍裂纹扩展,镁基体中稀土元素起到固溶强化作用,从而提高镁合金的高温抗拉强度。
The effects of different additions of rare earth elements on the microstructure and mechanical properties of AZ91D alloy were investigated. After adding rare earth mixed, the mechanical properties at room temperature did not significantly improve. At 100 ℃, the mechanical properties of the die-cast AZ91D alloy with 0.4% rare-earth content are almost the same as that of the non-mixed RE91 alloy. The tensile strength, yield strength and elongation of die-cast AZ91D alloy with 0.4% rare-earth content were 170MPa, 206MPa, 142MPa and 26% respectively, which were higher than that of die-cast AZ91D without mixed rare earth 15.7%, 10% and 30%. This is because the addition of an appropriate amount of rare earth, the formation of a higher thermal stability of the reinforcing phase, increasing the dislocation slip resistance and impede the crack growth, magnesium matrix rare earth elements play a solid solution strengthening effect, thereby increasing the magnesium alloy high temperature tensile strength.