摘要
Formation and sedimentation of Fe-rich intermetallics were studied in a commercial Al-Si-Cu-Fe alloy with extra additions of Mn. It is found that the introduction of extra Mn is an effective approach to lower the Fe level in the equilibrium liquid phase after sedimentation of solid Fe-rich phase at a temperature between its liquidus and solidus. The higher Mn/Fe mass ratio results in the lower Fe content in the retained alloy, during which Mn is also consumed and settled at the bottom of the melt as solid Fe-rich intermetallics. Therefore, the final Fe content in the alloy can be controlled by the Mn content and the holding temperature of the melt. The results confirmed a good agreement of the theoretical calculation and the experimental test with a specially designed 50 mm cylindrical casting. The sedimentation of Fe-rich intermetallics in the Al-Si-Cu-Fe alloy is completed at 600 °C after 10 min. The reduction of Fe content in the retained alloy is 31.4% when m（Mn）/m（Fe）=0.5 and 53.3% when m（Mn）/m（Fe）=1.0 in comparison with that in the original alloy. The settled Fe-rich intermetallics were identified as α-Al15（Fe,Mn）3Si2, which provided the lower balanced Fe concentration in the melt in comparison with other Fe-rich intermetallics.
研究锰添加对工业用Al-Si-Cu-Fe合金中富铁金属间化合物形成和析出的影响。发现在液固相温度之间经过固态富铁相的析出后,锰的加入是一种有效降低平衡液相中铁含量的方法。高的m(Mn)/m(Fe)质量比会降低实验合金中的铁含量,在此过程中锰被消耗,并且作为固态富铁金属间化合物沉积在熔体金属的底部。因此,合金中的最终Fe含量可以用锰含量和保温温度来控制。这些结果验证了专门设计的50 mm圆柱铸件的理论计算和实验测试的一致性。在600°C时,Al-Si-Cu-Fe合金中的富铁金属间化合物10 min后全部析出。与原始合金相比,当m(Mn)/m(Fe)质量比为0.5和1.0时,基体中的铁含量分别降低31.4%和53.5%。富铁金属间化合物为α-Al15(Fe,Mn)3Si2,与其他富铁金属间化合物相比,这种相可以提供较低的平衡铁浓度。
基金
financial support from TSB (UK) under project No. 101172
the EPSRC (UK) and Jaguar Cars Ltd. (UK) for financial support under the grant for the EPSRC Centre-LiME
