材料科学
等轴晶
Laves相
因科镍合金
微观结构
溶解
碳化物
棒
高温合金
相(物质)
冶金
位错
差示扫描量热法
固溶体
复合材料
金属间化合物
合金
化学工程
热力学
有机化学
化学
病理
工程类
替代医学
物理
医学
作者
N. Hasani,C. Dharmendra,Mehdi Sanjari,Fateh Fazeli,Babak Shalchi Amirkhiz,Hadi Pirgazi,G.D. Janaki Ram,Mohsen Mohammadi
标识
DOI:10.1016/j.matchar.2021.111499
摘要
Inconel 718 superalloy cylindrical rods were fabricated using the laser powder bed fusion (L-PBF) technology in the vertical orientation. The rods were stress-relieved at 980 °C for 15 min before cutting them from the build plate. The microstructure in this condition exhibited a significant amount of undesirable needle-like δ-phase precipitates and a small amount of interdendritic Laves phase that is finer in size. Differential Scanning Calorimetry (DSC) was used to determine the temperatures for solid-state phase transformations and appropriate temperature for solution-treatment. Solution-treatment was performed at 1065 °C for 1 h, followed by air cooling. The microstructures were characterized with specific reference to δ-phase and Nb segregation. Solution-treatment at 1065 °C was found to result in a significant elimination of micro-segregation (mainly Nb), complete dissolution of δ phase, considerable Laves dissolution, and partly undissolved carbide particles (few nm in size). Solution-treatment did not produce a significant change in the grain morphology (columnar dendritic) on a plane parallel to the build direction but more recrystallized and equiaxed grains were formed on a plane perpendicular to the build direction. The hardness of the solution-treated sample is comparable with wrought 718 alloys but lesser (115 HV) than in the stress-relieved condition attributing to the annihilation of dislocation tangles.
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