NiTi Shape Memory Marformed Alloy Studied by Electron Beam Precession TEM Orientation Mapping Method |
| P. Świec, M. Zubko, Z. Lekston and D. Stróż
Institute of Material Science, University of Silesia, 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland |
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| Severe plastic deformation by cold-rolling in martensitic state was applied to Ni50.4Ti49.6 shape memory alloy. Received materials with 17, 20, 25, and 35% deformation were further annealed at 450°C for 15 min. After such treatment hardness of this alloy increased significantly reaching 365 HV0.5 for highest deformation degree. Calorimetric studies revealed two-stage and two-step character of martensitic transformation occurring in all specimens. Nanocrystalline structure with average grain size 53, 34, 28, and 24 nm was obtained. In material with 35% of deformation amorphous regions containing a nuclei of B2 parental phase with average size of 5 nm were observed. To determine the crystallographic orientation of observed nanograins and for better phase analysis, electron beam precession transmission electron microscopy orientation mapping was performed. |
DOI: 10.12693/APhysPolA.131.1307 PACS numbers: 62.20.fg, 62.20.F-, 61.43.Dq, 61.66.Bi, 68.37.Ef, 62.25.-g, 64.70.Nd |