Abstract：GH4742 (Russian ЭП742) alloy is a typical high-alloyed hard-to-deform nickel-based superalloy turbine disk material. In this paper, GH4742 alloy is improved by adjusting the composition of Al, Ti and Nb, and a new type of nickel-based superalloy was invented. Use JMatPro to simulate the equilibrium phase diagram, and then use optical metallographic microscope and field emission scanning electron microscope to observe the alloy′s grain structure, carbides and γ′ phase distribution, and at the same time to detect the mechanical properties.The results show that the phase transition of the alloy in the equilibrium state from 1 400 ℃ to 300 ℃ during the cooling process can be summarized as L → L+γ → L+γ+MC →γ+MC+γ′ → γ+γ′+MC+μ → γ+γ′+μ+MC+M23C6 → γ+γ′+μ+MC+M23C6+σ. The volume fraction of γ′ phase precipitated at 780 ℃ is 40.88%. The forging deformation process is γ+γ′ dual phase zone deformation. After solution at 1 120 ℃, the microstructure after standard double aging treatment (850 ℃/6 h/AC+ 780 ℃/6 h/AC) clearly shows two different size grains. Small crystal grains (13 μm) are distributed around large crystal grains (100 μm) in a necklace shape. The carbides in this alloy are mainly MC (NbC, TiC, VC) of large size and irregular shape. The distribution state of the strengthening phase γ′ phase also has two different sizes. The average diameter of γ′I phase is 600 nm, the average diameter of γ′II phase is 150 nm. The good matching of the two sizes of γ′ phase strengthening makes the alloy have high strength and high plasticity at the same time, and excellent mechanical properties. The tensile strength at room temperature is 1 478 MPa, and the durability at 650 ℃/863 MPa is 194 h, which far exceeds the standard of 50 h at 650 ℃/823 MPa for GH4742 alloy.
张晓敏，秦鹤勇，于萍，田强，段然，张文云. 一种新型镍基高温合金组织及性能的研究[J]. 物理测试, 2022, 40(4): 18-23.
ZHANG Xiaomin,QIN Heyong,YU Ping,TIAN Qiang,DUAN Ran,ZHANG Wenyun. Study on the microstructure and properties of a new type of nickel-based superalloy. PHYSICS EXAMINATION AND TESTING, 2022, 40(4): 18-23.
2022, Vol. 40 
