Phosphorus plays an important role in the solidification, segregation and as-cast microstructure of superalloys. In order to control the as-cast microstructure and homogenization of IN783 alloy, the effect of phosphor...Phosphorus plays an important role in the solidification, segregation and as-cast microstructure of superalloys. In order to control the as-cast microstructure and homogenization of IN783 alloy, the effect of phosphorus on the as-cast microstructure and the solidification sequence of IN783 alloy was investigated and analyzed. The as-cast microstructure of IN783 alloy is constituted by γ matrix mainly located in dendrite core and segregation zone, together with β phase, blocky Laves phase and P-enriched phase mainly in interdendritic zone. Phosphorus hardly dissolves in β phase and blocky Laves phase dissolves in P-enriched phase. Thus, phosphorus inhibits the formation of blocky Laves phase, but promotes the formation of the P-enriched phase in the as-cast samples of IN783 alloy. As a result, the segregation of Nb in the γ matrix located in the segregation zone is decreased, consequently decreasing the area of the zone. The solidification sequence of IN783 alloy is L→ L+ γ→ L+ γ+ β phase→ L+ γ+ β phase+ Laves phase→γ+ β phase+ Laves phase + P-enriched phase.展开更多
Impact, tensile, and fatigue tests were performed in In783 alloy serving 4000, 23,000 and 48,000 h. The microstructure was then analysed by optical microscopy(OM), scanning electron microscopy(SEM), and transmission e...Impact, tensile, and fatigue tests were performed in In783 alloy serving 4000, 23,000 and 48,000 h. The microstructure was then analysed by optical microscopy(OM), scanning electron microscopy(SEM), and transmission electron microscopy(TEM) to probe the relationship between microstructure and properties. The results show that a new Ni_(5)Al_(3) phase is found, which grows gradually in β phase with serving time increasing,destroying the martensitic structure of the β phase, and degenerating the toughness of the β phase(approximately13.88% reduction). Therefore, the degradation of the βphase results in a sharp dropping of the resistance to stress accelerated grain boundary oxygen(SAGBO) during serving;thus, the intergranular fracture morphology degree increases with duration of service(almost 40% increase from the fractured surface). In addition, the strength of alloy will be gradually enhanced when the γ'phase becomes relatively bulky with serving time increasing due to considerable distortion of the dislocations as a result of the spacing of individual particles, in which any movement of the dislocation will have to overcome a larger number of obstacles per unit length.展开更多
文摘Phosphorus plays an important role in the solidification, segregation and as-cast microstructure of superalloys. In order to control the as-cast microstructure and homogenization of IN783 alloy, the effect of phosphorus on the as-cast microstructure and the solidification sequence of IN783 alloy was investigated and analyzed. The as-cast microstructure of IN783 alloy is constituted by γ matrix mainly located in dendrite core and segregation zone, together with β phase, blocky Laves phase and P-enriched phase mainly in interdendritic zone. Phosphorus hardly dissolves in β phase and blocky Laves phase dissolves in P-enriched phase. Thus, phosphorus inhibits the formation of blocky Laves phase, but promotes the formation of the P-enriched phase in the as-cast samples of IN783 alloy. As a result, the segregation of Nb in the γ matrix located in the segregation zone is decreased, consequently decreasing the area of the zone. The solidification sequence of IN783 alloy is L→ L+ γ→ L+ γ+ β phase→ L+ γ+ β phase+ Laves phase→γ+ β phase+ Laves phase + P-enriched phase.
基金financially supported by the National Key R&D Program of China (2016YFC081902)the Shenhua Guohua (Beijing) Electric Power Research Institute Co.,Ltd。
文摘Impact, tensile, and fatigue tests were performed in In783 alloy serving 4000, 23,000 and 48,000 h. The microstructure was then analysed by optical microscopy(OM), scanning electron microscopy(SEM), and transmission electron microscopy(TEM) to probe the relationship between microstructure and properties. The results show that a new Ni_(5)Al_(3) phase is found, which grows gradually in β phase with serving time increasing,destroying the martensitic structure of the β phase, and degenerating the toughness of the β phase(approximately13.88% reduction). Therefore, the degradation of the βphase results in a sharp dropping of the resistance to stress accelerated grain boundary oxygen(SAGBO) during serving;thus, the intergranular fracture morphology degree increases with duration of service(almost 40% increase from the fractured surface). In addition, the strength of alloy will be gradually enhanced when the γ'phase becomes relatively bulky with serving time increasing due to considerable distortion of the dislocations as a result of the spacing of individual particles, in which any movement of the dislocation will have to overcome a larger number of obstacles per unit length.
