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针对Al-18Mg_2Si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-18Mg_2Si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Mg_2Si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3~5μm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Mg_2Si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-18Mg_2Si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。
Aiming at the poor mechanical properties of Al-18Mg-2Si alloy, OM, XRD and SEM were used to study the influence of Nd and Nd-Ti-B composite modification on the microstructure and mechanical properties of Al-18Mg-2Si alloy. The results show that after 0.25% Nd modification, the size of primary Mg_2Si decreases from unmodified 65μm to 26μm, and the amount of α-Al phase in primary Mg2Si increases; the distance between eutectic Mg2Si and unmetered Mg3Si decreases from 1μm, the size of eutectic decreases and the number increases. After 0.25% Nd + 0.1% Ti + 0.02% B metamorphic treatment, the size of primary Mg_2Si decreases to 15μm, and the number increases 1 times. After 0.25% Nd and 0.25% Nd + 0.1% Ti + 0.02% B metamorphic treatment, the tensile strength of Al-18Mg_2Si alloy increased by 9.6% and 23.6%, and the elongation increased by 33% and 75% . Nd-Ti-B metamorphism is better than single Nd metamorphism.