Ce对Mg-5Si合金中初生Mg2Si相变质的影响

Modifying Effect of Ce Addition on Primary Mg2Si Phase in Mg-5Si Alloy

利用扫描电子显微镜(SEM)、能量色散光谱仪(EDS)、光学显微镜(OM)、ICP光谱仪及X射线衍射(XRD)等手段研究了Ce对Mg-5Si合金中Mg2Si相变质的影响。结果表明:添加不同量的Ce使Mg-5Si合金中的初生Mg2Si相的形貌从粗大的树枝状变为多边形状,共晶Mg2Si由汉字状变为了细纤维状或点状。Ce的添加量为1.2%时变质效果最佳,初生Mg2Si的尺寸从48μm减小到9μm或更小。同时,在1.6%Ce变质的合金中发现了短棒状的Mg-Si-Ce化合物。Ce促进了Mg2Si的形核,并抑制了Mg2Si的各向异性生长。

The modifying effect of Ce addition on primary Mg2 Si phase in Mg-5 Si alloy was investigated by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),optical microscopy(OM),ICP spectrometry and X-ray diffraction(XRD).The results show that the morphology of the primary Mg2 Si phase changed from coarse dendritic shape to polygonal shape with the addition of various amount of Ce.The eutectic Mg2 Si phase changed from Chinese-characters shape to fine fiber shape or dot shape.The optimum modification effect was obtained when the amount of Ce addition was 1.2%.The size of the primary Mg2 Si decreased from 48μm to 9μm or less.Whilst,short rod-shaped Mg-Si-Ce compounds were found in the alloy with 1.6%Ce.Ce promotes the nucleation of Mg2 Si,and inhibits its anisotropic growth.