Martensite transformation of 50Ni-xhf(50-x)Ti shape memory alloys
The characteristics of martensite transformation in NiTi-Hf alloys, such as transformation temperature, enthalpy and entropy changes, hysteresis width, Young`s modulus and damping, and martensite structure, are investigated in this paper. The results indicate that: (1) The martensite of the NiTi-Hf alloys is thermoelastic martensite. (2) The transformation temperatures and thermodynamic parameters depend on the Hf content. (3) The crystal structure of the high temperature parent phase is of the CsCl-type, regardless of the alloy composition. The primary product of the martensite transformation at room temperature for alloys with x < 6 is monoclinic B19` martensite, while for 20< x <30 at%, the crystal structure is orthorhombic B19.
- Research Organization:
- Florida International Univ., Miami, FL (United States)
- OSTI ID:
- 253904
- Report Number(s):
- AD-A--303906/2/XAB; CNN: Contract DAAL03-91-G-0245
- Country of Publication:
- United States
- Language:
- English
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