P变质对Si合金化AZ91镁合金显微组织和力学性能的影响

Effect of P modifying on microstructures and mechanical properties of Si alloying AZ91 magnesium alloys

采用X射线衍射、高分辨透射电镜等现代分析测试手段研究了Al-P中间合金变质处理对AZ91＋0．7％Si合金的显微组织和力学性能的影响。研究结果表明：AZ91＋0．7％Si合金中加入一定量的Al-P中间合金变质处理后，Mg2Si的形貌发生了显著变化，由汉字状变为细小的颗粒状，其颗粒的平均尺寸为6～10μm，且基体组织的平均晶粒尺寸由原来的100μm减小到45μm左右，β-Mg17Al12相出现不同程度的断网，从而使AZ91＋0．7％Si合金的力学性能得到显著提高。说明Al-P中间合金对Si合金化的AZ91镁合金具有很好的变质强化功效，是一种Mg2Si化合物的强化粒化剂。

The microstructures and mechanical properties of AZ91 containing 0.7% Si alloys modified by Al-P master alloy were observed using XRD and TEM. The results show that addition of certain amount Al-P master alloy into AZ91 containing 0.7% Si alloys leads to morphology change of Mg2Si phase from Chinese script to fine particle with the average particle size between 6 and 10 μm. The average grain size of the matrix reduces from 100 μm to 45 μm. The morphology of β-Mg17Al12 phase varys from continuous nets to discontinuous nets. Consequently, the mechanical properties of AZ91 containing 0.7% Si alloys are improved dramatically. It indicates that the Al-P master alloy has excellent modifying and strengthening effects on AZ91 containing 0.7 % Si alloys and is a effective graining additive.