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Selective laser melting was used to produce an aluminum alloy Al-8.5Fe-1.3V-1.7Si(wt%). The effects of heat treatment on microstructure evolution and phase stability during long-term thermal exposure of the deposits were investigated. Results show that the microquasi-crystalline phase, Al12(Fe,V)3Si and AlmF e metastable phases coexisted with α-Al in the as-produced alloy. Annealing at 400 °C resulted in decomposition of microquasi-crystalline phase and supersaturated α-Al into Al12(Fe, V)3Si phase in the fusion zone, accompanied by the decrease in alloy hardness. The activation energy of this decomposition process was 115 k J/mol. A more homogenous microstructure was obtained after annealing at 400 °C for 60 min,which was resistant to coarsening exposed at 425 °C up to 500 h. The Al12(Fe,V)3Si and AlmF e phases were coarsened at 475 and 525 °C with increasing the exposure time. Coarsening of Al12(Fe,V)3Si phase was attributed to a combination of volume diffusion and grain boundary diffusion mechanism of Fe. Heat treatment at 600 °C resulted in accelerated microstructure coarsening and formation of large-sized equilibrium phases, which signi?cantly degraded the room temperature microhardness.
Selective laser melting was used to produce an aluminum alloy Al-8.5Fe-1.3V-1.7Si (wt%). The effects of heat treatment on microstructure evolution and phase stability during long-term thermal exposure of the deposits were investigated. Results show that the microquasi-crystalline phase, Al12 (Fe, V) 3Si and AlmF e metastable phases coexisted with α-Al in the as-produced alloy. Annealing at 400 ° C resulted in decomposition of microquasi-crystalline phase and supersaturated α-Al into Al12 (Fe, V) 3Si phase in the fusion zone, accompanied by the decrease in alloy hardness. The activation energy of this decomposition process was 115 kJ / mol. A more homogenous microstructure was obtained after annealing at 400 ° C for 60 min , which was resistant to coarsening exposed at 425 ° C up to 500 h. The Al12 (Fe, V) 3Si and AlmF e phases were coarsened at 475 and 525 ° C with increasing exposure time. Coarsening of Al12 (Fe, V) 3Si phase was attributed to a combination of volume diffusion and grain bounda ry Diffusion mechanism of Fe. Heat treatment at 600 ° C resulted in accelerated microstructure coarsening and formation of large-sized equilibrium phases, which signi? cantly degraded the room temperature microhardness.