Phase field modeling of shearing processes of a dual-lobed γ″|γ′|γ″ coprecipitate
Phase field modeling of shearing processes of a dual-lobed γ″|γ′|γ″ coprecipitate
复制标题
双瓣 γ-γ|γ-γ|γ-γ 共沉淀物剪切过程的相场建模
DOI：
10.1016/j.actamat.2023.118693
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发表时间：
2023
期刊：
影响因子：
9.4
通讯作者：
Wang, Yunzhi
中科院分区：
文献类型：
--
作者：
Feng, Longsheng;Shi, Rongpei;Zenk, Christopher H.;Mills, Michael J.;Wang, Yunzhi
镍基高温合金IN718是20世纪60年代发展起来的航空航天工业中应用最广泛的商用合金之一。优异的机械性能在很大程度上归功于共格γ '和γ”沉淀物的强化。这两个阶段的变形机制已分别得到很好的研究。最近的实验表征表明，这两个阶段在各种形态的共沉淀物，有人认为，这些共沉淀物可能会导致改善加强相比，他们的单片对应。然而，这些共沉淀物的变形机制仍然没有得到很好的理解。在这项研究中，我们进行了微观相场模拟，与广义堆垛层错（GSF）能量表面fromumab initiocalculations作为输入，系统地研究了剪切过程的周期性阵列的双叶共沉淀物以及单片沉淀物。我们发现共沉淀物中γ′和γ″相之间的耦合迫使位错在两相中采取高能剪切路径，如果它们是整体形式，则不会发生这种情况。这种耦合还在共沉淀物中产生堆垛层错构型，这需要高应力来形成。因此，共沉淀物的存在通常应增加对位错剪切的抗性并导致更高的强度水平。在剪切过程中观察到的各种故障配置记录作为参考，为未来的比较与实验观察。层错剪切和微孪晶之间的联系进行了讨论。在这项研究中分析的机制加深了我们的理解共沉淀对合金强度的影响，并可能形成多沉淀强化合金设计策略的基石。
The Ni-based superalloy IN718 is one of the most widely used commercial alloy in the aerospace industry since its development in 1960s. The excellent mechanical properties have been attributed in a great deal to strengthening by coherent γ′ and γ″ precipitates. The deformation mechanisms of these two phases have been well studied individually. Recent experimental characterization has shown coprecipitates of these two phases in a variety of morphologies and it was argued that these coprecipitates may lead to improved strengthening as compared to their monolithic counterparts. However, the deformation mechanisms of these coprecipitates are still not well understood. In this study, we performed microscopic phase field simulations, with generalized-stacking-fault (GSF) energy surfaces fromab initiocalculations as inputs, to systematically study the shearing processes of a periodical array of dual-lobed coprecipitates as well as monolithic precipitates. We found that the coupling between the γ′ and γ″ phases in the coprecipitates forces dislocations to take high energy shearing pathways in both phases that would not occur if they were in monolithic forms. The coupling also creates stacking fault configurations in the coprecipitates that require high stress to form. Thus, the presence of coprecipitates in general should increase the resistance to dislocation shearing and lead to higher strength levels. Various fault configurations observed during the shearing process are documented as a reference for future comparison with experimental observations. The link between stacking fault shearing and microtwinning is also discussed. The mechanisms analyzed in this study deepens our understanding of coprecipitation effects on alloy strength and may form a cornerstone for multi-precipitate strengthened alloy design strategies.