Stress-induced amorphization at moving crack tips in NiTi.
In situ fracture studies on thin-film NiTi intermetallic compounds have been carried out in the high-voltage electron microscope at Argonne National Laboratory. Local stress-induced amorphization of regions directly in front of moving crack tips has been observed under tensile loading conditions. The stress-induced amorphization at crack tips exhibits a temperature dependence similar to that of ion-induced amorphization of NiTi. The upper limiting temperature for stress-induced amorphization is the same as that for ion-induced amorphization of crystalline NiTi and for amorphous phase formation during ion-beam mixing of Ni and Ti multilayer specimens. This upper limiting temperature of 600K is also the lowest temperature at which stress-induced amorphous phase crystallizes during isothermal annealing. This isothermal crystallization temperature is nearly 200K less than the kinetic crystallization temperature during heating of unrelaxed NiTi glasses formed by rapid quenching or vapor phase deposition.
- Research Organization:
- Argonne National Lab., IL (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-31-109-ENG-38
- OSTI ID:
- 8104
- Report Number(s):
- ANL/MSD/CP-93805; TRN: AH200117%%18
- Resource Relation:
- Conference: Fall Meeting of the Materials Research Society, Boston, MA (US), 12/05/1997--12/05/1997; Other Information: PBD: 29 Jan 1998
- Country of Publication:
- United States
- Language:
- English
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