Microstructural degradation of polycrystalline superalloys from oxidized carbides and implications on crack initiation

Abstract

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The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy

“…In addition to surface eruption and volume expansion, pores around oxidised carbides have also been observed by them and supposed to cause microcracks. The similar observation of higher GND density around crosssectioned oxidised carbides has been made by Kontis et al [14] recently. They also reported suspected softer area of recrystallization adjacent to oxidised carbide and caused by elements diffusion through dislocations, which might also contribute to the weakening of oxidised carbides areas [14].…”

“…To investigate carbide and oxide connectivity as well as secondary and primary crack networks within the bulk sample, a three-dimensional imaging was performed using layer-by layer grinding and 14 polishing method. Fig.…”

“…For alloys subjected to high temperature fatigue loading, crack initiation in terms of surface oxidation and stress assisted intergranular oxidation have received considerable academic attention [10]. In particular, since fatigue cracks initiated by oxidised carbides were observed by Connolley et al [11], the importance of carbides oxidation has been reported [12] and its effects on local lattice and chemical changes in adjacent areas have been studied in detail 4 recently in [13,14]. However, with the advancements in materials processing techniques and heat treatments, cast defects have been reduced and their influence on the fatigue life have been greatly minimised.…”

Correlative Microscopy—Novel Methods and Their Applications to Explore 3D Chemistry and Structure of Nanoscale Lattice Defects: A Case Study in Superalloys

“…1a. 20,21 A series of APT specimens were prepared from locations highlighted in blue following the conventional procedure outlined by Thompson et al 22 and using a commercially available flat-top Si coupon and conventional clip holder. A representative tomographic reconstruction is shown in Fig.…”

Interfaces and defect composition at the near-atomic scale through atom probe tomography investigations

“…We have also turned our attention to deformed microstructures in Ni-based superalloys exhibiting a /' microstructure [53][54][55] . In a recent article, we reported on the strong segregation of  stabilizing elements, primarily Cr and Co onto a complex network of linear features appearing within ' precipitates in various alloys, incl.…”