中文摘要：

针对Al-18Mg2Si合金力学性能差的问题,采用OM、XRD、SEM等手段研究单独添加Nd与Nd-Ti-B复合变质处理对Al-18Mg2Si合金凝固组织与力学性能的影响。结果表明,经0.25%的Nd变质处理后,初生Mg2Si尺寸由未变质的65μm减小到26μm,包裹初生Mg2Si的α-Al相数量增加;共晶Mg2Si片间距由未变质的35μm降低到1μm,共晶团尺寸减小,数量增加;经0.25%的Nd＋0.1%的Ti＋0.02%的B变质处理后,初生Mg2Si尺寸减小到15μm,数量增加1倍。经0.25%的Nd和0.25%的Nd＋0.1%的Ti＋0.02%的B变质处理后,Al-18Mg2Si合金的抗拉强度分别提高9.6%和23.6%,伸长率分别提高33%和75%。Nd-Ti-B变质处理效果优于单一Nd变质处理。

英文摘要：

In order to solve the problem of poor mechanical properties,effects of Nd and Nd-Ti-B modification treatment on solidification structure and mechanical properties of Al-18Mg2Si alloy were investigated by OM,XRD and SEM.The results reveal that,for Al-18Mg2Si alloy after 0.25% Nd modification,the size of primary Mg2Si is decreased from 65μm to 26μm,and the number ofα-Al phase enclosing primary Mg2Si is increased.In addition,the lamellar space of eutectic Mg2Si is reduced from 35μm to 1μm with the decrease of size and increases of eutectic colony number,compared with those of ones without modification.After 0.25%Nd＋0.1%Ti＋0.02%B compound modification,the size of primary Mg2Si is reduced to 15μm with great increase of content.The tensile strength of Al-18Mg2Si alloy after0.25%Nd and 0.25%Nd＋0.1%Ti＋0.02%B modification is improved by 9.6%and 23.6%,and the elongation is increased by 33% and 75%,respectively.The effect of Nd-Ti-B compound modification is superior to that of single Nd modification.