Mn元素对Al-Si合金富铁相析出影响的热力学计算
Thermodynamic Study of the Influence of Mn on the Precipitation of Fe-Rich Phase in Al-Si Alloy

本研究选取不同Mn元素含量的Al-7 wt%Si-0.2 wt%Fe铝液为研究对象，利用热力学软件定量计算了Mn元素添加量对铝液Scheil-Gulliver冷却凝固过程的析出相。结果表明：不同Mn元素含量的铝液冷却过程中相转变顺序有所不同，添加一定量的Mn元素可利于铝液凝固过程中析出Al₃MnSi₂相；添加Mn元素并不会大幅减少完全凝固后β-AlFeSi相的质量比，且不同Mn元素含量的铝合金中β-AlFeSi相质量比相差不超过1%，说明难以通过添加Mn元素来减少铝液完全凝固后的β-AlFeSi相质量比；铝液凝固末期，β-AlFeSi与Al₃MnSi₂发生共晶反应，Al₃MnSi₂对β-AlFeSi的形貌可能具有改性作用，是β-AlFeSi与Al₃MnSi₂的共晶相呈现出不规则形状的主要原因。
In this paper, Al-7 wt%Si-0.2 wt%Fe liquid aluminum with different Mn content was selected as the research object, and the effect of Mn addition on the precipitated phase of Scheil-Gulliver cooling process of aluminum liquid was quantitatively calculated by thermodynamic software. The results show that, the phase transition sequence of aluminum liquid cooling with different Mn content is different, and the addition of a certain amount of Mn element can facilitate the precipitation of Al₃MnSi₂ phase during the solidification of aluminum liquid. The addition of Mn does not significantly reduce the mass ratio of β-AlFeSi phase after complete solidification, and the difference in the mass ratio of β-AlFeSi phase between aluminum alloys with different Mn content is less than 1%, indicating that it is difficult to reduce the mass ratio of β-AlFeSi phase after complete solidification by adding Mn element. At the end of liquid aluminum solidification, β-AlFeSi reacts with Al₃MnSi₂, and Al₃MnSi₂ may modify the morphology of β-AlFeSi, which is the main reason for the irregular shape of the eutectic phase of β-AlFeSi and Al₃MnSi₂.