First-principles-aided design of a new Ni-base superalloy: Influence of transition metal alloying elements on grain boundary and bulk cohesion
First-principles-aided design of a new Ni-base superalloy: Influence of transition metal alloying elements on grain boundary and bulk cohesion
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DOI：
10.1016/j.actamat.2014.08.047
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发表时间：
2015-01-01
期刊：
影响因子：
9.4
通讯作者：
Razumovskii, I. M.
中科院分区：
文献类型：
--
作者：
Razumovskiy, V. I.;Lozovoi, A. Y.;Razumovskii, I. M.
提出了一种设计镍基多晶高温合金的新方法。在这种方法中，我们假设高温合金的蠕变断裂特性主要由晶界 (GB) 和伽马基体主体中原子间键合的强度决定。 GB 的理想分离功 W-sep 用作控制界面机械强度的基本热力学量，而合金成分的部分内聚能 chi 用于表征其对本体强度的贡献。使用 Sigma 5 (2 1 0)[1 0] 对称倾斜 GB 作为 Ni 中代表性的高角度 GB，我们计算了全套 4d 和 5d 过渡金属杂质的 W-sep、chi 和 GB 偏析能、E-seg，其中我们添加了 B（典型的微合金化添加物）、S 和 Bi（众所周知的镍基有害杂质） 高温合金）。分析的目的是确定那些表现出高度偏析成 GB 的倾向、在本体中具有正的（最好是高的）部分内聚能以及对 GB 的 W-sep 有积极影响的元素。我们将这些元素称为低合金添加物。我们的研究表明 Zr、Hf、Nb、Ta 和 B 是最有前途的低合金添加物。我们的下一步是将第一步中发现的元素引入新型粉末冶金 (P/M) 镍基高温合金中。随后的测试结果证实，与现有的俄罗斯粉末冶金合金EP741NP相比，新制造的粉末冶金高温合金确实在高温下表现出优异的机械性能。 (C) 2014 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
A new approach to the design of Ni-base polycrystalline superalloys is proposed. In this approach, we assume that the creep rupture characteristics of a superalloy are mostly determined by the strength of interatomic bonding at grain boundaries (GBs) and in the bulk of gamma matrix. The ideal work of separation, W-sep, of a GB is used as a fundamental thermodynamic quantity that controls the mechanical strength of an interface, whereas the partial cohesive energy, chi, of an alloy component serves to characterize its contribution into the strength of the bulk. Using the Sigma 5 (2 1 0)[1 0] symmetric tilt GB as a representative high-angle GB in Ni, we calculate W-sep, chi, and GB segregation energies, E-seg for the complete set of 4d and 5d transition metal impurities, to which we add B (a typical microalloying addition), S and Bi (notoriously known as harmful impurities in Ni-base superalloys). The purpose of the analysis is to identify the elements that demonstrate a high tendency to segregate to GBs, have positive (preferably high) partial cohesive energies in the bulk, and have positive impact on W-sep of GBs. We refer to these elements as low-alloying additions. Our study reveals Zr, Hf, Nb, Ta and B as the most promising low-alloying additions. Our next step is to introduce the elements found in the first step into a new powder metallurgy (P/M) Ni-base superalloy. The results of the subsequent testing confirm that the newly created P/M superalloy indeed demonstrates superior mechanical properties at high temperatures compared to the existing Russian P/M alloy EP741NP. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.