Abstract With the aim of understanding the effect of creep defects in the γ′ phase on the creep resistance, the atomic structure and elemental segregation behavior of stacking faults (SFs), three types of SF interactions and anti-phase boundaries (APBs) in a Co-Al-W-based single-crystal superalloy crept at 1000 °C/137 MPa up to 1.0% strain were investigated. Both superlattice intrinsic and extrinsic stacking faults (SISF and SESF) were observed in the γ′ precipitates, and the interactions of such faults had different configurations. Both V- and T-like configurations can be composed of SISF-SISF, SISF-SESF and SESF-SESF interactions, while the X-like configuration was only observed to be composed by SISF-SISF interaction. The strengthening effect and mechanism of such SF interactions on the creep resistance are discussed based on their density and formation mechanism. W elemental segregation was present along the SISFs and SESFs. In contrast, only the γ forming element Co was enriched near the leading partial dislocations (LPDs) of the SISFs/SESFs, stair-rod dislocations and APBs. The rate limiting step of the expansion of the SFs was estimated to be the drag effect induced by the Co diffusion. In addition, the local phase transformation from the L12 to A1 structure at the intersection of SFs was mainly attributed to the Co supersaturation and aided by wetting phenomenon from the APB.

中文翻译：

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Co-Al-W基单晶高温合金高温低应力蠕变缺陷的原子结构和元素偏析行为

摘要 为了解γ′相蠕变缺陷对蠕变阻力、堆垛层错（SFs）的原子结构和元素偏析行为、三种类型的SF相互作用和反相界（APBs）的影响。研究了 Co-Al-W 基单晶高温合金在 1000 °C/137 MPa 下蠕变至 1.0% 应变。在γ'沉淀物中观察到超晶格内在和外在堆垛层错（SISF和SESF），并且这些层错的相互作用具有不同的构型。V 型和 T 型构型都可以由 SISF-SISF、SISF-SESF 和 SESF-SESF 相互作用组成，而 X 型构型仅观察到由 SISF-SISF 相互作用组成。基于它们的密度和形成机制讨论了这种SF相互作用对抗蠕变性的增强作用和机制。W 元素偏析沿 SISF 和 SESF 存在。相比之下，只有 γ 形成元素 Co 在 SISF/SESF、楼梯杆位错和 APB 的前导部分位错 (LPD) 附近富集。SFs 膨胀的限速步骤估计是由 Co 扩散引起的阻力效应。此外，SFs 交点处从 L12 到 A1 结构的局部相变主要归因于 Co 过饱和并借助 APB 的润湿现象。只有 γ 形成元素 Co 在 SISFs/SESFs、楼梯杆位错和 APBs 的前导部分位错 (LPDs) 附近富集。SFs 膨胀的限速步骤估计是由 Co 扩散引起的阻力效应。此外，SFs 交点处从 L12 到 A1 结构的局部相变主要归因于 Co 过饱和并借助 APB 的润湿现象。只有 γ 形成元素 Co 在 SISFs/SESFs、楼梯杆位错和 APBs 的前导部分位错 (LPDs) 附近富集。SFs 膨胀的限速步骤估计是由 Co 扩散引起的阻力效应。此外，SFs 交点处从 L12 到 A1 结构的局部相变主要归因于 Co 过饱和并借助 APB 的润湿现象。