Plastic deformation mechanisms in a crept L12 hardened Co-base superalloy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2013-06, Vol.571, p.13-18
• Main Authors: Pyczak, F., Bauer, A., Göken, M., Neumeier, S., Lorenz, U., Oehring, M., Schell, N., Schreyer, A., Stark, A., Symanzik, F.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cobalt based superalloys; Condensed matter: structure, mechanical and thermal properties; Creep; Cross-disciplinary physics: materials science; rheology; Defects and impurities in crystals; microstructure; Dislocations; Exact sciences and technology; Growth from solutions; Linear defects: dislocations, disclinations; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Methods of crystal growth; physics of crystal growth; Physics; Stacking faults and other planar or extended defects; Structure of solids and liquids; crystallography; Synchrotron X-ray diffraction; Transmission electron microscopy
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2013.02.007

Plastic deformation mechanisms in a crept L12 hardened Co-base superalloy are investigated by transmission electron microscopy. The deformation happens mainly in the cobalt solid solution matrix by slip of ordinary a/2〈101〉{111} dislocations and rafting of the γ′ precipitates perpendicular to the external compressive stress axis is observed. Dislocation structures are early stages of the development of γ/γ′ interfacial dislocation networks. Furthermore, γ′ precipitates are sheared by partial dislocations generating stacking faults which sometimes extend over matrix channels and neighbouring γ′ precipitates. Due to the positive lattice mismatch at creep temperature the dislocation activity in matrix channels perpendicular to the compressive external stress axis is less pronounced compared to parallel channels.