Influence of Thermomechanical Treatment on Structure and Crack Propagation in Nanostructured Ti–50.26 at%Ni Alloy

• Published in: Metallography, microstructure, and analysis microstructure, and analysis, 2014-02, Vol.3 (1), p.46-57
• Main Authors: Kreitcberg, A., Brailovski, V., Prokoshkin, S., Inaekyan, K.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Materials Science; Metallic Materials; Nanotechnology; Structural Materials; Surfaces and Interfaces; Technical Article; Thin Films
• ISSN: 2192-9262; 2192-9270
• DOI: 10.1007/s13632-013-0114-4

The fatigue propagation of processing-induced microcracks in severely deformed Ti–50.26 at%Ni alloy’s samples was investigated. The processing schedules included cold rolling (CR) with logarithmic strains of ɛ  = 0.75 and 1.2, and a combination of CR( ɛ  = 1), intermediate annealing (400 °C, 1 h), and warm rolling ( ɛ  = 0.2, T  = 150 °C). The final step of the thermomechanical processing schedules consisted of post-deformation annealing at 400 °C, 1 h. The resulting microstructures were studied using transmission electron microscopy. Using optical microscopy, the processing-induced edge cracks’ lengths and concentrations were measured before and after multicycle superelastic and stress generation/relaxation testing. From the functional fatigue point of view, nanocrystalline (NC) microstructure demonstrated higher tolerance to small cracks than mixed NC + nanosubgrained structure.