Influence Of Mn Addition On Microstructure And Phase Formation Of Spray-deposited Al-25si-xfe-ymn Alloy

摘要

The hypereutectic Al-25Si-xFe-yMn alloys (with the ratio of Mn to Fe (y/x) between 0 and 1 wt.%) were synthesized by spray forming. The microstructure of the spray-deposited preforms as well as the over-sprayed powders was investigated. The addition of Mn was aimed to improve the mechanical properties of the alloys through forming the particulate α-Al_(15)(Fe,Mn)_3Si_2 phase to replace the acicular δ-Al_4FeSi_2 and β-Al_5FeSi phases formed in the alloy without Mn. XRD results revealed that, for alloy with y/x = 0, almost single acicular δ-Al_4FeSi_2 phase presented in the over-sprayed powders, whereas the spray-deposited preform consisted of both δ-Al_4FeSi_2 and β-Al_+5FeSi phases. For alloy with y/x = 0.625, the particulate α-Al_(15)(Fe,Mn)_3Si_2 phase began to appear in the deposited preform. When y/x increased to 1.0, δ-Al_4(Fe,Mn)Si_2, β-Al_5(Fe,Mn)Si and α-Al_(15)(Fe,Mn)_3Si_2 phases coexisted in the over-sprayed powders, whereas only particulate α-Al_(15)(Fe,Mn)_3Si_2 phase could be observed in the deposited preform. These results can be explained with schematics for transformation of the intermetallics in light of the phase forming mechanisms involved during spray deposition.