Sc、Zr对Al-4Fe合金组织的细化作用

Refining Effect of Sc and Zr Compound Alloying on Microstructure of the Al-4Fe Alloy

Sc、Zr复合添加到Al-4Fe合金中,改变了合金铸态晶粒的形态。变质剂在合金凝固过程中提供优质的异质形核核心,有效地细化铝基体晶粒;Sc、Zr在初生Al3Fe相周围的富集在一定程度上阻碍了Fe原子在结晶前沿的扩散,抑制了初生Al3Fe相的生长,起到了细化初生相的作用。当加入0.3%的Sc和0.2%的Zr时,合金组织的细化效果相对较好,初生Al3Fe相转变为针状、粒状和花朵状,合金的抗拉强度得到提高。探讨了微量Sc、Zr复合添加对过共晶铝铁合金的细化作用机理。

The as-cast grain morphology of the alloy was changed with adding the trace scandium and zirconium compound into the hypereutectic Al-4Fe alloy.The grain in the aluminum matrix is refined effectively as a result of the modification agent providing high quality heterogeneous nucleation core in the process of alloy solidification.The diffusion of the Fe atoms is inhibited partly in the frontiers of the crystallization because of the enrichment of Sc and Zr around the primary Al3 Fe phases which plays the role in inhibiting and refining the growth of primary Al3 Fe phase.With 0.3% Sc and 0.2% Zr compound addition in the Al-4Fe alloy,the desirable refining effects can be observed,and the primary Al3 Fe phase is changed from the shape of coarse needles to be fine needle-like,particle-like and flower-like,so the tensile strength of the alloy is also improved.In addition,the refining mechanism of minor Sc and Zr compound modifying the hypereutectic Al-4Fe alloy was expound.