The effect of solid solution and gamma prime on the deformation modes in Ni-based superalloys
The effect of solid solution and gamma prime on the deformation modes in Ni-based superalloys
复制标题
固溶体和γ ′对镍基高温合金变形方式的影响
DOI：
10.1016/j.actamat.2020.04.004
复制
发表时间：
2020-08-01
期刊：
影响因子：
9.4
通讯作者：
Preuss, Michael
中科院分区：
文献类型：
--
作者：
Harte, Allan;Atkinson, Michael;Preuss, Michael
了解多晶镍基高温合金的变形、强化和失效机制，对于开发下一代适用于高要求环境的合金是必要的。在这里，的目的是检查的各种方式，其中溶液和γ '沉淀强化影响三个镍基高温合金的变形行为，通过变形映射和调查，在多个长度尺度。这是通过使用高分辨率数字图像相关性来量化局部应变、晶格旋转的电子背散射衍射和电子沟道衬度成像来研究位错介导的变形机制来实现的。这种方法弥补了位错-γ相互作用的纳米级显微镜和力学性能（如屈服应力、流动应力和应变硬化率）的宏观尺度测量之间的差距。固溶强化合金中的变形通过滑移带细化机制进行，这导致晶界处的位错堆积水平较低，因此与相邻物的晶粒变形相容性较好。γ强化合金中的变形通过滑移面软化机制发展，并且所产生的高应变局部化冲击晶界，在边界处产生扩散应变区域。在粗γ '变体中，在较大的沉淀物周围存在更多的奥罗万环和交叉滑移，更多的滑移面是活跃的，并且发生更多的晶粒尺度交叉滑移，导致更大的局部摩擦应力，因此更大的宏观流动应力和应变硬化率。我们提供的证据表明，在γ '强化合金中，交叉的非共面滑移带之间的相互作用更大，这有助于通过逐渐减小滑移距离来实现应变硬化。在固溶强化合金中没有观察到这种机制。(C)2020 Acta Materialia Inc.爱思唯尔有限公司出版
Understanding the deformation, strengthening and failure mechanisms in polycrystalline nickel-base superalloys is necessary to develop next generation alloys for application in highly demanding environments. Here, the aim is to examine the various ways in which solution- and gamma' precipitation-strengthening affect the deformation behaviour of three Ni-based superalloys through deformation mapping and investigation at multiple length-scales. This is achieved using high-resolution digital image correlation to quantify local strain, electron backscattered diffraction for lattice rotations and electron channelling contrast imaging to investigate dislocation-mediated mechanisms of deformation. This approach bridges the gap between nanoscale microscopy of dislocation-gamma' interactions and macro-scale measurements of mechanical properties, such as yield stress, flow stress and the strain-hardening rate. Deformation in solution-strengthened alloys progresses by a slip band refinement mechanism, which results in low levels of dislocation pileup at grain boundaries and so better grain deformation compatibility with neighbours. Deformation in the gamma'-strengthened alloys evolves through a glide plane softening mechanism and the resulting high strain localisation impinges on grain boundaries, creating diffuse strain regions at the boundary. In the coarse-gamma' variant there is more Orowan looping and cross slip around larger precipitates, more slip planes are active and more grain-scale cross slip takes place, resulting in greater local friction stresses and therefore greater macroscopic flow stresses and strain-hardening rates. We provide evidence of greater interaction between intersecting non co-planar slip bands in the gamma'-strengthened alloys, which contributes to the strain-hardening by progressively decreasing the slip distance. This mechanism is not observed in the solution-strengthened alloy. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd.