不同Si含量对免热处理强化压铸铝硅合金组织和性能影响的研究

Study on Effects of Different Si Content on Microstructure and Properties of Heat Treatment Free Die Casting Al-Si Alloy

研究了不同Si含量对免热处理强化压铸铝硅合金组织性能影响。结果表明:Al-6%Si合金中的析出相主要沿晶界析出,分布不均匀。其形貌类似杆状,具有尖锐的棱角。随着Si含量提升,析出相所占比重显著上升,并且粒子尺寸增大,同时存有少量未充分溶解的粗大块状初晶硅。在铝硅合金中主要存在两种不同类型的析出相,一种是长针状AlSiFe相,另一种是明亮粗大块状AlSiMnFe相。长针状AlSiFe相具有较高的表面能,能够有足够的空位吸纳Mn原子,从而随着凝固过程进行自发转变为更稳定的块状AlSiMnFe相。在该过程中Mn元素被大量消耗,析出相粒子中的Mn/Fe值下降。随着Si含量的增加,试样的抗拉强度得到了显著提高,但是塑性和抗冲击性能并未协同提升。

The effect of different Si content on the microstructure and properties of heat treatment free die casting Al-Si alloy was studied.The results show that the precipitates in Al-6%Si alloy mainly precipitated along the grain boundary and distributed unevenly,which shape is like a rod,with sharp edges and corners.With the increase of Si content,the proportion of precipitated phase increases significantly,and the particle size increases.At the same time,there is a small amount of undissolved massive primary silicon.In Al-Si alloy,there are mainly two different types of precipitates,one is long needle like AiSiFe phase,the other is bright coarse block like AiSiMnFe phase.The long needle like AiSiFe phase has high surface energy and owns enough vacancies to absorb Mn atoms,which can spontaneously transform into a more stable blocky AlSiMnFe phase during solidification process.In this process,Mn element is largely consumed,the Mn/Fe value in precipitated phase particles decreases.With the increase of Si content,the tensile strength of the sample is significantly improved,but the plasticity and impact resistance are not improved together.