镍基单晶高温合金小角度晶界组织特征

doi:10.13251/j.issn.0254-6051.2025.12.003

摘要/Abstract

摘要： 采用双籽晶定向凝固法制备了含10°小角度晶界的镍基单晶高温合金试样,表征铸态和热处理态下小角度晶界处的显微组织。结果表明,铸态下小角度晶界存在共晶、初生和竞争3种晶界类型。其中,共晶类型晶界的比例最高,分布着大量的不规则共晶和少量粗大的γ′相以及碳化物;初生类型晶界表现为尺寸较大的γ相和γ′相以及一层狭长的γ′相;竞争类型晶界主要是规则的马赛克共晶或者较大的γ′相与γ相。经热处理后,小角度晶界上主要为薄的γ相,其中共晶类型晶界中仍有少量残留共晶和碳化物,而初生类型晶界的两侧则存在不完整γ′相,其晶界上还有块状γ相和富Re、W颗粒;竞争类型晶界两侧保留较完整的γ′相,且无析出物存在。

关键词: 单晶高温合金, 定向凝固, 双晶, 小角度晶界, 微观组织

Abstract: Utilizing the double-seed directional solidification method, low-angle grain boundary specimens were fabricated to investigate the microstructural characteristics of as-cast and heat-treated low-angle grain boundaries with misorientation of 10° in nickel-based single crystal superalloys. The results show that the as-cast grain boundaries comprise three types of boundaries: eutectic-type, birth-type, and competitive-type. The eutectic-type grain boundary is the most common, characterized by a high density of irregular eutectic structures, along with minor amounts of coarse γ′ phase and carbide precipitates. The birth-type grain boundary is characterized by large γ and γ′ phases, accompanied by a narrow layer of γ′ phase. The competitive-type grain boundary displays either regular mosaic eutectic structures or larger γ′ and γ phase. Following heat treatment, low-angle grain boundaries typically exhibit thin layers of γ phase. Specifically, a small amount of residual eutectic and carbides persist in the eutectic-type grain boundaries. In contrast, the birth-type grain boundaries show incomplete γ′ phase on both sides, with blocky γ phase and Re- and W-rich particles found on the grain boundaries. However, the competitive-type exhibits more complete γ′ phase on both sides of the grain boundaries, with no obvious precipitate observed.

Key words: single crystal superalloy, directional solidification, bi-crystal, low-angle grain boundary, microstructure

中图分类号:

TG146.2

李丞, 曹敏, 李亚峰, 顾建宏, 吕斌, 陈信锗, 苏振华, 陈贤. 镍基单晶高温合金小角度晶界组织特征[J]. 金属热处理, 2025, 50(12): 16-22.

Li Cheng, Cao Min, Li Yafeng, Gu Jianhong, Lü Bin, Chen Xinzhe, Su Zhenhua, Chen Xian. Microstructural characteristics of low-angle grain boundaries in Ni-based single crystal superalloy[J]. Heat Treatment of Metals, 2025, 50(12): 16-22.

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