Strengthening Mechanisms in Polycrystalline Multimodal Nickel-Base Superalloys
Strengthening Mechanisms in Polycrystalline Multimodal Nickel-Base Superalloys
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DOI：
10.1007/s11661-009-9858-5
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发表时间：
2009-07-01
影响因子：
2.8
通讯作者：
Pollock, T. M.
中科院分区：
文献类型：
--
作者：
Kozar, R. W.;Suzuki, A.;Pollock, T. M.
研究了具有不同晶粒尺寸和单峰、双峰或三峰析出相分布的多晶γ - γ高温合金。为了评估微观结构的特定特征对材料整体强度的贡献，开发并评估了一个模型，该模型考虑了固溶强化、Hall-Petch效应、强弱对耦合模式下的析出相剪切以及析出相之间的位错弯曲。还考虑了Ni3Al相的交叉滑移诱发硬化和多模态组织中析出相的尺寸分布。本文介绍了高温下沉淀剪切对流动应力峰值贡献的新实验观察结果。对具有相当屈服强度的各种合金进行了研究，发现它们的强度来自于微成分（机制）的不同组合。在各种微观结构中，反相边界能（APB）对强度的影响较大。经过低于γ溶剂温度热处理的材料受益于强大的Hall-Petch贡献，而超溶剂热处理材料的大部分强度来自于它们对沉淀剪切的抵抗力。
Polycrystalline gamma-gamma' superalloys with varying grain sizes and unimodal, bimodal, or trimodal distributions of precipitates have been studied. To assess the contributions of specific features of the microstructure to the overall strength of the material, a model that considers solid-solution strengthening, Hall-Petch effects, precipitate shearing in the strong and weak pair-coupled modes, and dislocation bowing between precipitates has been developed and assessed. Cross-slip-induced hardening of the Ni3Al phase and precipitate size distributions in multimodal microstructures are also considered. New experimental observations on the contribution of precipitate shearing to the peak in flow stress at elevated temperatures are presented. Various alloys having comparable yield strengths were investigated and were found to derive their strength from different combinations of microconstituents (mechanisms). In all variants of the microstructure, there is a strong effect of antiphase boundary (APB) energy on strength. Materials subjected to heat treatments below the gamma' solvus temperature benefit from a strong Hall-Petch contribution, while supersolvus heat-treated materials gain the majority of their strength from their resistance to precipitate shearing.