Composition effect on elastic properties of model NiCo-based superalloys

• 作 者: Weijie Li Chongyu Wang
• 机 构: Department of Physics, Tsinghua University, Beijing 100084, China;Institute of Applied Physics and C
• 出 处: 中国物理B（英文版）
• 发表日期: 2020年2期
• 关键词: NiCo-based superalloys elastic constants special quasi-random structures (SQS) d

NiCo-based superalloys exhibit higher strength and creep resistance over conventional superalloys. Compositional effects on elastic properties of theγ andγ’ phases in newly-developed NiCo-based superalloys were investigated by first-principles calculation combined with special quasi-random structures. The lattice constant, bulk modulus, and elastic constants vary linearly with the Co concentration in the NiCo solution. In the selected (Ni, Co)3(Al, W) and (Ni, Co)3(Al, Ti) modelγ’ phase, the lattice constant, and bulk modulus show a linear trend with alloying element concentrations. The addition of Co, Ti, and W can regulate lattice mismatch and increase the bulk modulus, simultaneously. W-addition shows excellent performance in strengthening the elastic properties in theγ’ phase. Systems become unstable with higher W and Ni contents, e.g., (Ni0.75Co0.25)3(Al0.25 W0.75), and become brittle with higher W and Co addition, e.g., Co3(Al0.25 W0.75). Furthermore, Co, Ti, and W can increase the elastic constants on the whole, and such high elastic constants always corre-spond to a high elastic modulus. The anisotropy index always corresponds to the nature of Young’s modulus in a specific direction.