中國有色金屬學報(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 26 No. 2 February 2016 |
（1. Key Laboratory of Superlight Material and Surface Technology, Ministry of Education,
Harbin Engineering University, Harbin 150001, China;
2. Center for Biomedical Materials and Engineering, College of Materials Science and Chemical Engineering,
Harbin Engineering University, Harbin 150001, China;
3. Department of Materials Science and Engineering, College of Engineering,
Peking University, Beijing 100871, China;
4. Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa 450000, Russia）
Abstract:The effect of annealing temperature on the martensitic transformation of a Ti49.2Ni50.8 alloy processed by equal channel angular pressing (ECAP) was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The as-ECAP processed and subsequently annealed Ti49.2Ni50.8 alloys consist of B2 parent phase, Ti4Ni2O phase and B19′ martensite at room temperature. Upon cooling, all samples show B2→R→B19′ two-stage transformation. Upon heating, when the annealing temperature is less than 400 °C, the samples show B19′→R→B2 two-stage transformation; when the annealing temperature is higher than 500 °C, the samples show B19′→B2 single-stage transformation. The B2-R transformation is characterized by wide interval due to the dislocations introduced during ECAP.
Key words: TiNi alloy; equal channel angular pressing; martensitic transformation; annealing temperature
