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研究稀土元素Nd(0~0.4%,质量分数)对近共晶Al-12Si合金显微组织与力学性能的影响。结果表明:在0.3%Nd改性的Al-12Si合金中形成一种亚微米或纳米尺寸的Al2Nd相。在Al-12Si合金中添加稀土元素Nd能显著细化合金中的α(Al)相,粗生硅相转变为细小颗粒状,共晶硅由粗大针状变成细小纤维状。在改性效果最佳的Al-12-0.3Nd合金的Si相表面观察到少量的生长孪晶。力学性能测试结果表明:添加Nd元素后,Al-12Si合金的力学性能得到改善,当合金中Nd元素含量达到0.3%时,合金的力学性能达到最优,抗拉强度(UTS)为252 MPa,伸长率(EL)为13%。合金力学性能的改善主要归因于合金中Si相形貌的改善和细小Al2Nd相颗粒的形成。
The effect of rare earth element Nd (0 ~ 0.4%, mass fraction) on the microstructure and mechanical properties of near-eutectic Al-12Si alloy was studied. The results show that a submicron or nanosize Al2Nd phase is formed in 0.3% Nd-modified Al-12Si alloy. The addition of rare earth element Nd to Al-12Si alloy can remarkably refine the α (Al) phase in the alloy, and the coarse silicon phase transforms into small particles. The eutectic silicon changes from coarse needle to fine fiber. A small amount of growth twins were observed on the surface of Si phase of Al-12-0.3Nd alloy with the best modification effect. The results of mechanical properties test show that the mechanical properties of Al-12Si alloy are improved when Nd is added. When the content of Nd in the alloy reaches 0.3%, the mechanical properties of Al-12Si alloy are optimized. The tensile strength (UTS) Elongation (EL) is 13%. The improvement of the mechanical properties of the alloy is mainly attributed to the improvement of the morphology of the Si phase in the alloy and the formation of fine Al2Nd phase particles.