固溶处理对P变质Al-30%Si合金微观组织和性能的影响

Effect of solution treatment on microstructure and mechanical properties of P-modified Al-30%Si alloy

采用P对熔铸法制备的Al-30%Si合金进行变质处理,并对合金进行固溶处理,研究了P变质和固溶处理对Al-30%Si合金微观组织和性能的影响。结果表明:P变质对Al-30%Si合金中初晶硅具有显著的细化效果,加入0.15%P可使初晶硅平均尺寸减小至33.2μm,同时,共晶硅也得到明显的细化;530℃×6 h单级固溶处理只能对初晶硅和共晶硅的形态起到一定的改善作用;而570℃×2 h+530℃×2 h二级固溶处理,能够使初晶硅形态由多角块状转变为接近球状,并且,共晶硅由针状转变成细小的球状颗粒,均匀弥散的分布于Al基体中。经P变质和单级固溶处理后,Al-30%Si合金抗弯强度由铸态的125.76 MPa提高至218.31 MPa,而经过二级固溶处理可使合金的抗弯强度进一步提升至232.45 MPa。

The Al-30%Si alloy prepared by melting casting was modified by P , and then the alloy was treated by solid solution treatment. The effect of P modification and solution treatment on microstructure and properties of the Al-30% Si alloy was studied. The results show that the P modification has a remarkable refine effect on the primary silicon in the Al-30% Si alloy, and the average size of the primary silicon is reduced to 33. 2μm by the addition of 0. 15% P, and the eutectic silicon is also refined. The single-step solution treatment at 530℃ for 6 h can only improve the morphology of the primary and the eutectic silicon;and the two-step solution treatment at 570 ℃ for 2 h and at 530℃ for 2 h can change the morphology of primary silicon from polygonal block to nearly spherical, and the morphology of eutectic silicon from needle to fine spherical particles, which are evenly dispersed in Al matrix. The bending strength of the Al-30% Si alloy increases from 125. 76 MPa to 218. 31 MPa after P modification and single-step solution treatment, and the bending strength of the alloy is further increased to 232. 45 MPa after the two-step solution treatment.