Vacancy mediated alloying strengthening effects on γ/γ′ interface of Ni-based single crystal superalloys: A first-principles study

Interface Alloying Design to Improve the Dispersion of TiB2 Nanoparticles in Al Composites: A First-Principles Study

“…Meanwhile, three substitution sites (Al i , Al i –1 , Al i –2 ) from the interface to the bulk region are employed to determine the optimal substitution position of the X atom (Figure a). To evaluate the site preference of the alloying atoms and the stability of the alloyed interface, the relative interface formation energy (Δ E f ) was calculated using the following equation , where E interface ( E interface X ) is the total energy of the original (alloyed) interface supercell; N Total and N X are the numbers of the total atoms and alloyed atoms in the supercell, respectively; E Al bulk and E X bulk are the ground state energies of the individual atoms in the corresponding elemental bulk states, respectively; and Δ E f is the relative formation energy of the alloyed interface. A negative Δ E f value indicates that the alloyed interface is more stable than the original interface, and a positive value indicates interface instability.…”

“…from the interface to the bulk region are employed to determine the optimal substitution position of the X atom (Figure 3a). To evaluate the site preference of the alloying atoms and the stability of the alloyed interface, the relative interface formation energy (ΔE f ) was calculated using the following equation 30,46…”

“…29 Therefore, the relative interface energies of the alloyed interface have been widely employed in many related studies. For example, Zhao et al 30 compared the formation energy and the Griffith work of the original and alloyed (i.e., Re, Mo, Ta, and Cr) Ni/Ni 3 Al interfaces to explain the vacancy-mediated alloying strengthening mechanism of Ni-based single crystal superalloy. Phongpreecha et al 31 theoretically verify the mechanisms of the CuO interlayer enhancing the wetting and adhesion of the Ag/YSZ interface by DFT calculation.…”

Prediction on elastic properties of Nb-doped Ni systems

“…The calculated results showed that the most preferable substitution sites of alloying elements didn't be changed by a Ni vacancy on (001)γ' plane, except Cr element, and the alloying elements at Al site in γ' enhanced the interfacial bonding strength of γ/γ' interface, among which the strengthening effect of Re was the best. 17 Although many solid-solution strengthening elements, such as Ru, Rh, Pd, Ir, Os, Re, Mo, Ta, Cr and Pt, have been researched by first−principles simulations, there are few studies about Nb element which can improve solid solution strengthening effect of γ matrix phase (Ni crystal). In order to reveal the influence of Nb on γ matrix phase from the atomic and electronic perspective, Ni system doping with Nb element in five different concentrations are systematically investigated by first−principles simulations.…”

Effect of Ta and Re on the fracture strength and creep strength of Ni/Ni₃Al interface

“…大量的 γ/γ′相界面。γ/γ′相界是镍基单晶超合金中的主要结构缺陷，在很大程度上 可以影响镍基单晶合金的力学性能 [3] 。高温合金的组成、结构和性能是紧密相关 的。镍基高温合金中还含有很多种合金元素 [4,5] ，其力学性能也会受到合金原子在 γ/γ′界面处分布的影响，在合金中掺杂一定量的合金化元素就可以对合金力学性 能起到改善作用。 Chen 等人 [6] 研究了多种元素在 Ni/Ni 3 Al 相界面上的强化效果及 其机理，使用第一性原理计算了 Mo、W、Ti、Re、Cr 等元素添加前后界面剪切 强度和结合强度，发现 W 对剪切强度增强效果最好，Mo 对界面结合强度增强效 果最好，也发现增强背后的机理是大多数合金原子与近邻的 Ni 原子之间会产生 强成键作用；通过研究 S 掺杂在界面中的成键特性发现界面处 S 与 Ni 原子间形 成的强键是导致界面硫脆的主要原因 [7] 。在断裂强度方面的研究，Gong [8] 等人研 究了 Re、Ru、Ta、Cr、W、Co 等金属元素添加对界面的强化作用，通过计算界 面断裂功发现对界面断裂强度提升效果最好的是 Re 元素，Co 元素的作用效果较 差。Peng 等人 [9][10][11][12] Re 和 P 进行在界面的协同化研究， Re-P 原子对相互排斥但 Re 的添加对 P 的分布 位置无影响。温玉锋 [13] 等人采用第一性原理方法对层错能进行了计算研究，发现 合金原子与 Ni 原子之间半径差的不同以及价电子数差的不同都会对层错能大小 3 产生影响，但合金化原子掺杂与否对层错能的影响更为重要，其中 Re、W、Mo 元素对合金固溶强化效果最好。Zhu [14] 等人也利用第一原理方法从形成能、断裂 能以及层错能角度研究了合金化元素 Re、 Ta 和 W 元素对 Ni/Ni 3 Al 界面的强化行 为，得出合金原子对界面的强化行为是通过与近邻 Ni 原子的杂化来完成的，其 中 Re 原子的杂化行为最强。 Zhao [15] 等人研究了在界面上 Ni 空位的存在对合金元 素占位分配的影响以及空位与合金元素对界面强度的协同作用，发现除 Cr 元素 之外，Ni 空位的存在不会改变合金元素的占位，而且当界面中存在空位时合金元 素依然对界面表现出强化效果，其中 Re 元素的作用效果是最突出的，提高了合 金的蠕变性能。孙敏 [16] 等人进行了关于纯界面和 Re 掺杂界面的空位计算，结合 攀爬图像-微动弹性带(CI-NEB)方法进行密度泛函理论计算研究了镍基单晶高温 合金的扩散现象，描述了空位介导的扩散的四种情况的理论模型以及扩散过程， 计算了空位形成能，迁移能和活化能，并研究扩散行为的电子效应。 Re 可以显著提高镍基单晶高温合金的蠕变和疲劳断裂强度 [17] ，这是通过 Re 进入合金的 γ 基体中阻碍位错运动来实现的 [18] ，进入 γ′相的也可以产生对 γ′相的 强化作用 [19] 。而 Ta 是一种具有高熔点且能对合金起到固溶强化作用的合金元素，…”