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研究了不同含量的富La混合轻稀土(RE)和钇(Y)对Mg2Si/AZ91D复合材料中初生Mg2Si相形貌的影响。结果表明,混合轻稀土RE和Y对Mg2Si/AZ91D复合材料中的初生Mg2Si相均有明显的细化变质效果,但Y对初生Mg2Si相的细化变质效果优于等量混合轻稀土。合金液经0.8%的混合轻稀土RE或Y变质后,初生Mg2Si相由粗大的树枝状转变为细块状或颗粒状;当RE或Y加入量达到1.2%时,均出现过变质现象,初生Mg2Si相再次明显粗化。其变质机理主要与RE、Y和它们的化合物富集于Mg2Si相生长表面,从而抑制其生长有关。
The effects of different La-rich mixed rare earth (RE) and yttrium (Y) on the morphology of primary Mg2Si phase in Mg2Si / AZ91D composites were studied. The results show that mixed rare earth RE and Y have obvious metamorphic effect on the primary Mg2Si phase in Mg2Si / AZ91D composite, but the effect of refinement and metamorphism of Y on primary Mg2Si phase is better than that of mixed rare earth. When the alloy liquid is modified by 0.8% RE or Y, the primary Mg2Si phase changes from coarse dendrites to fine lumps or granules. When the amount of RE or Y added reaches 1.2% Mg2Si phase significantly roughened again. The metamorphic mechanism is mainly related to the enrichment of RE, Y and their compounds on the growth surface of Mg2Si phase, thereby inhibiting its growth.