摘要
The recrystallization behaviors of a nickel-based single crystal superalloy during heat treatment at 1,200℃ for 4 h with various cooling rates were studied.Results show that the thickness of recrystallization layer decreases with the increase of cooling rate.In addition,the microstructures ofγ′phase in the recrystallization region are different in various cooling rates.In the high cooling rates(70,100℃·min^(-1)),small size and high volume fraction ofγ′phases are formed in the recrystallization region.It is also found that irregular fine secondaryγ′phases are precipitated between matrix channels with an average size of 150 nm in the original matric(100℃·min^(-1)).The sizes of the secondaryγ′phase decrease with the increase of cooling rate.In contrast,large size and small volume fraction ofγ′phases are formed in the recrystallization region,and a grain boundary layer is formed under a low cooling rate(10℃·min^(-1)).The evolution mechanism of recrystallization at various cooling rates during heat treatment is analyzed.
基金
financially supported by the National Natural Science Foundation of China(No.92060104)
the National Science and Technology Major Project(No.2017-VII-00080102)
the Shanghai Municipal Science and Technology Committee Grant(No.20511107700)。
