Selective Laser Melting of an Al-Fe-V-Si Alloy: Microstructural Evolution and Thermal Stability

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2017,（4）
• 页码范围: 389-396
• 页数: 8页
• 语种: 英文

摘要

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 AlmFe metastable phases coexisted with α-Al in the as-produced alloy.Annealing at 400 ℃ 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 ℃ for 60 min,which was resistant to coarsening exposed at 425 ℃ up to 500 h.The Al12(Fe,V)3Si and AlmFe phases were coarsened at 475 and 525 ℃ 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 ℃ resulted in accelerated microstructure coarsening and formation of large-sized equilibrium phases,which significantly degraded the room temperature microhardness.