Investigation on solution heat treatment response and γ′ solvus temperature of a Mo-rich second generation Ni based single crystal superalloy. (October 2020)

• Record Type: Journal Article
• Authors: Ai, Cheng; Xi, Liguo; Wang, Bo; Sun, Yanghui; Zhang, Jun; Su, Haijun; Yang, Wenchao; Liu, Lin; Sun, Zhiping; Chen, Yongnan
• Is Part Of: Intermetallics. Volume 125(2020:Oct.)
• Publication Date: 2020-10
• Subjects: Mo-rich single crystal superalloy -- Solution heat treatment -- Microstructure -- Homogenization of alloying elements -- DICTRA -- γ′ solvus temperature; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2020.106896
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: A multi-step solution heat treatment regime of a Mo-rich Ni based single crystal superalloy (Alloy Mo) was designed, and the effect of each solution heat treatment step on microstructure, microsegregation degree and phase transformation characteristic temperatures of Alloy Mo was investigated by experimental analysis and dynamic calculation (via DICTRA). Homogenizations of microstructure and Re element in as-cast Alloy Mo were obtained via first step solution heat treatment (lowest temperature and shortest time) and last step solution heat treatment (highest temperature and longest time), respectively. In addition, appropriate diffusion length for dynamic calculation of homogenization of Re element was determined. Meanwhile, solution heat treatment increased the solidus temperature of as-cast Alloy Mo, while it had less effect on liquidus temperature and γ′ solvus temperature. Moreover, as compared with W-rich single crystal superalloys, effects of solution heat treatment on both solidus temperature and γ′ solvus temperature of Mo-rich single crystal superalloy were lower. Additionally, γ′ solvus temperatures of Mo-rich single crystal superalloys were lower than those of W-rich single crystal superalloys. Highlights: Homogenization of Re was obtained via last step solution heat treatment (SHT). Appropriate diffusion distance of DICTRA calculation was determined. SHT responses of Mo-rich and W-rich single crystal (SC) superalloys were different. γ′ solvus temperatures of Mo-rich and W-rich SC superalloys were compared.