Ming Yang, Tao Luo, Lei Lei, Yun Jiang, Pan-Zhi Wang, Fa-Hong Xu
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引用次数: 0
Abstract
Uniaxial tensile testing explored the Portevin–Le Chatelier (PLC) effect in nickel-based superalloys featuring high Mo/Cr mass ratios, focusing on the influence of variations in the initial microstructure on the deformation behavior at room and elevated temperatures. Experimental results indicated that the PLC effect was observed solely in the high-temperature tensile curves. However, the deformation mechanisms and characteristics of the PLC effect varied with different initial microstructures. Solid solution (SS) and over-aged (OA) samples exhibited C-type serrations, while under-aged (UA) and peak-aged (PA) specimens, featuring short- and long-range ordered phases, respectively, exhibited A + B type serrations in their tensile curves. Microstructural evolution from the SS to the UA, PA and OA states changed their stacking fault energy (SFE), leading to a sequential transformation in the plastic deformation mechanisms during high-temperature tensile deformation: stacking fault (SF) → nanotwin → microtwin → SF. C-type serrations in the SS samples were associated with high solute-atom contents and SF formation. The PLC effects in the UA and PA samples were predominantly caused by solute atom pinning dislocations. Although precipitates and twins were not the primary drivers of the PLC effect, they impeded dislocation migration, exacerbated solute-atom segregation and enhanced dislocation pinning, generating A + B-shaped serrations. In the OA specimens, precipitated phases induced interfacial mismatch under thermal-force coupling. SF shearing of the precipitated phase and subsequent re-dissolution facilitated the formation of C-type serrations, whose PLC effect was induced by the combined action of dynamic strain aging (DSA), SFs of the matrix and diffusion-controlled pseudo-locking mechanisms.
单轴拉伸试验探索了具有高钼/铬质量比的镍基超级合金中的波特文-勒夏特列（PLC）效应，重点研究了初始微观结构的变化对室温和高温下变形行为的影响。实验结果表明，仅在高温拉伸曲线中观察到 PLC 效应。然而，PLC 效应的变形机制和特征随不同的初始微观结构而变化。固溶体（SS）和过老化（OA）试样表现出 C 型锯齿，而欠老化（UA）和峰值老化（PA）试样分别具有短程和长程有序相，其拉伸曲线表现出 A + B 型锯齿。从 SS 到 UA、PA 和 OA 状态的微观结构演变改变了它们的堆积断层能（SFE），导致高温拉伸变形过程中塑性变形机制的顺序转变：堆积断层（SF）→纳米孪晶→微孪晶→SF。SS 样品中的 C 型锯齿与高溶质原子含量和 SF 的形成有关。UA 和 PA 样品中的 PLC 效应主要是由溶质原子钉扎位错引起的。虽然析出物和孪晶不是产生 PLC 效应的主要驱动因素，但它们阻碍了位错迁移，加剧了溶质原子偏析，增强了位错钉扎，从而产生了 A + B 型锯齿。在 OA 试样中，析出相在热力耦合作用下诱发了界面错配。析出相的SF剪切和随后的再溶解促进了C型锯齿的形成，其PLC效应是由动态应变老化（DSA）、基体的SF和扩散控制的伪锁定机制共同作用引起的。
期刊介绍：
Rare Metals is a monthly peer-reviewed journal published by the Nonferrous Metals Society of China. It serves as a platform for engineers and scientists to communicate and disseminate original research articles in the field of rare metals. The journal focuses on a wide range of topics including metallurgy, processing, and determination of rare metals. Additionally, it showcases the application of rare metals in advanced materials such as superconductors, semiconductors, composites, and ceramics.
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