"Twin plus ' phase" Microstructure Regulation for a Novel Ni-based Wrought Superalloy and High Temperature Mechanical Properties

The "twin+gamma' phase" composite structure was constructed in a novel Ni-based wrought superalloy by thermomechanical treatment, and the evolution of twin and.' phases was investigated by EBSD and SEM. Meanwhile, the high temperature mechanical properties of the alloy at 760 degrees C were studied. The results show that the "twin+gamma' phase" composite structure can effectively improve the high temperature mechanical properties of the alloy, and with the increase in the length fraction of the annealing twin, the thickness of the twin lamellar increases, and the high temperature strength of the material decreases. When the rolled alloy (epsilon-68%) is annealed at 1120 degrees C for 15 min and subjected to two-stage aging treatment (650 degrees C/24 h/AC and 760 degrees C/16 h/AC), the length fraction of twins in the "twin+gamma' phase" composite structure is 25.38% and the average size of gamma' phase is 32.21 nm, the yield strength of the alloy increases from 775 MPa (solid solution state) to 1184 MPa, and the elongation after fracture increases from 3.18% to 18.96%. "Twin+gamma' phase" composite structure can effectively improve the high-temperature mechanical properties of the superalloy, which provides a novel strategy for improving the high-temperature mechanical properties of superalloys.