Abstract The site occupancy, lattice misfit and elastic modulus of Ni-based single crystal superalloys are investigated by combining the first principles exact muffin-tin orbital method and coherent-potential approximation. The site preference of alloying elements in γ′-Ni3Al can be classified into four types: Co, Fe, Ru and Ir occupy Ni site or Cr, Mo, Re, Ti, V occupy Al anti-site (namely alloying elements occupy Al site while the removed Al occupy Ni site). Ti and V are the alloying elements which stabilize the γ′-Ni3Al. The lattice misfit and the difference of elastic properties between γ and γ′ phases are the causes of γ′ rafting, while the alloying elements will improve the differences. The effects of 1 at. % ~5 at. % alloying elements on lattice constant and misfit are studied, because of biggish atomic radius, Ir, Mo, Ti, Re and Ru increase the lattice constant of γ/γ′ phase much faster, and the alloying elements have some impacts on the lattice misfit of γ/γ′ phase. Re is the most remarkable alloying element which improves the elastic modulus of Ni-based superalloys.

中文翻译：

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合金元素对镍基单晶高温合金晶格失配和弹性的第一性原理计算

摘要 结合第一原理精确松饼-锡轨道法和相干电位近似，研究了镍基单晶高温合金的位点占有率、晶格失配和弹性模量。γ'-Ni3Al中合金元素的位点偏好可分为四种：Co、Fe、Ru、Ir占据Ni位或Cr、Mo、Re、Ti、V占据Al反位（即合金元素占据Al位）而去除的Al占据Ni位点）。Ti和V是稳定γ'-Ni3Al的合金元素。γ、γ'相的晶格错配和弹性性能的差异是引起γ'漂流的原因，而合金元素会改善这种差异。1处的影响。%~5 处。研究了合金元素对晶格常数和失配的百分比，因为原子半径较大，Ir、Mo、Ti、Re和Ru使γ/γ'相的晶格常数提高得更快，合金元素对γ/γ'相的晶格失配有一定的影响。Re是提高镍基高温合金弹性模量的最显着的合金元素。