Al-3P变质Al-18Si合金的显微组织与力学性能

Microstructure and mechanical properties of Al-18Si alloy modified by Al-3P master alloy

用Al-3P作为变质剂对Al-18Si合金进行变质处理,利用光学显微镜、Image Pro Plus 6.0软件、扫描电镜和万能电子试验机等研究变质剂加入量w(Al-3P)(0~1.0%)和变质温度(750~850℃)对合金显微组织与拉伸性能的影响。结果表明,变质处理后,初晶硅的尺寸减小,面积分数增大。当变质温度为800℃时,随w(Al-3P)增加,初晶硅的尺寸先减小后增大,初晶硅的面积分数先增大后减小,w(Al-3P)为0.6%时初晶硅尺寸最小,平均尺寸为14μm,w(Al-3P)为0.8%时初晶硅面积分数达到最大值14.4%。当w(Al-3P)为0.8%时,随变质温度升高,Al-18Si合金中的初晶硅面积分数减小,初晶硅尺寸先减小后增大,变质温度为800℃时初晶硅尺寸最小,约为15μm。与未变质的Al-18Si合金相比,在800℃加入0.8%Al-3P变质处理后,合金的抗拉强度和伸长率分别提高17.6%和109%,拉伸断口呈现明显的韧性断裂特征。

Al-18Si alloy was modified by Al-3P master alloy.The effects of adding amount of alterant w(Al-3P)(0?1.0%)and modification temperature(750?850℃)on microstructures and tensile properties of the alloy were investigated by optical microscope(OP),Image Pro Plus 6.0,scanning electron microscopy(SEM)and universal testing machine.The results show that the size of primary Si decreases and its area fraction increases after modification.With the increase of w(Al-3P),the size of primary Si first decreases and then increases,and the area fraction of primary Si first increases and then decreases when Al-18Si alloy was modified at 800℃.When the adding amount of alterant w(Al-3P)is 0.6%,the size of primary Si is the smallest,and the average size is 14μm.When the adding amount of w(Al-3P)is 0.8%,the area fraction of primary Si reaches the maximum of 14.4%.When the adding amount of w(Al-3P)is 0.8%,the area fraction of primary Si in Al-18Si alloy decreases with the increase of modification temperature.The size of primary Si decreases first and then increases.The size of primary Si is the smallest of 15μm when the alloy is modified at 800℃.Compared with unmodified Al-18Si alloy,the tensile strength and elongation of Al-18Si alloy increase by 17.6%and 109%respectively after modified with w(Al-3P)0.8%at 800℃.The fracture mode of the modified Al-18Si alloy is ductile fracture.