Microstructural evolution of a Ni-Co based superalloy during hot compression atγ'sub-/super-solvus temperatures  

作　　者：Peng Liu Rui Zhang Yong Yuan Chuanyong Cui Faguang Liang Xi Liu Yuefeng Gu Yizhou Zhou Xiaofeng Sun 

机构地区：[1]Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China [2]School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China [3]Xi'an Thermal Power Research Institute Co.Ltd.,Xi'an 710032,China

出　　处：《Journal of Materials Science & Technology》2021年第18期66-81,共16页材料科学技术（英文版）

基　　金：the financial support from the National Natural Science Foundation of China(No.51671189);the Ministry of Science and Technology of China(Nos.2017YFA0700703 and 2019YFA0705304)。

摘　　要：The effects of strain rate on the microstructural evolution and deformation mechanism of a Ni-Co based superalloy were investigated by isothermal compression tests performed atγ'sub-solvus(1090℃)andγ'super-solvus temperatures(1150℃)with a wide strain rate range from 0.001 to 10 s^(-1)under a true strain of 0.693.Electron backscatter diffraction(EBSD),electron channeling contrast imaging(ECCI)and transmission electron microscope(TEM)techniques were used to characterize the microstructures.The results revealed that the dynamic recrystallization(DRX)volume fraction increased and stored energy of theγ'matrix grains decreased with increasing the strain rate duringγ'sub-solvus temperature deformation,while the opposite phenomena were observed duringγ'super-solvus temperature deformation.The comprehensive effect of initial grain size,primaryγ'phase,twins and adiabatic temperature rise led to these results.The primaryγ'particles undergone the deformation behavior within itself and obviously accelerated the DRX of the matrix.The microstructural evolution proved that discontinuous dynamic recrystallization(DDRX)was the dominant mechanism during the hot deformation carried out at bothγ'sub-solvus andγ'super-solvus temperatures.Primaryγ'particles obviously accelerated the nucleation step and retarded the growth step of DDRX duringγ'sub-solvus temperature deformation.Besides,the acceleration effect of primaryγ'particles on DDRX increased with the increase of strain rate.Continuous dynamic recrystallization(CDRX)was confirmed to be an assistant mechanism duringγ'super-solvus temperature deformation and was promoted with the increase of strain rate.

关 键 词：Ni-Co based superalloy Strain rate Primaryγ'precipitates Dynamic recrystallization Microstructural evolution 

分 类 号：V263[航空宇航科学与技术—航空宇航制造工程] TG132.3[一般工业技术—材料科学与工程]