含稀土高硅铝合金的组织特征

Microstructure feature of high silicon content aluminum alloys with RE

为深入研究含稀土(RE)高硅铝合金的组织特征,将质量分数为0.08%P和质量分数为0.6%RE复合变质Al-20%Si-2%Cu-1%Ni-xMg(x=0.4%,0.8%)高硅铝合金浇入金属模具中成形.通过光学显微镜(OM)、X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)等测试方法,分析了该合金的相组成.结果表明:合金中生成Mg2Si相、Al-Si-Cu-Ni-RE相、AlCuNi相、AlFeMnSi相等金属间化合物;合金中加入质量分数为0.6%RE能较好地变质共晶Si,但过剩的RE易生成针状的Al-Si-Cu-Ni-RE相,该富RE五元化合物的形态在T6热处理前后变化不明显;T6热处理后合金中粗大的AlCuNi相粒状化,且分布较均匀.

Al-20%Si-2%Cu-1%Ni-xMg （x=0.4%,0.8%） high silicon aluminum alloys with complex modification of 0.08%P and 0.6%RE（rare earth） was formed by pouring into permanent mould to research their microstructure features.And the constituent phases of the alloys were studied by optical microscope （OM）,X-ray diffraction （XRD）,scanning electron microscope （SEM）,and energy disperse spectroscopy （EDS）.The results show that intermetallic compounds such as Mg2Si,Al-Si-Cu-Ni-RE,AlCuNi and AlFeMnSi phase were formed in the matrix.The eutectic silicon phase was modified moderately with 0.6%RE addition,but the over-amount RE caused to form acicular five element compound Al-Si-Cu-Ni-RE which was not changed obviously by T6 treatment.However,the coarse phases of AlCuNi were granular and distributed uniformly after T6 treatment.