J. Phys. IV France
Volume 05, Numéro C8, Décembre 1995International Conference on Martensitic Transformations – ICOMAT 95
|Page(s)||C8-1023 - C8-1028|
|Publié en ligne||11 juillet 2014|
Temperature and Uniaxial Stress Dependence of the Martensitic Transformation Temperature in Ni63 Al37
Physics Department, John Carroll University, Cleveland, OH 44118, U.S.A.
A study of the martensitic transformation in Ni63Al37 single crystals was made using optical, ultrasonic and atomic force microscope techniques. The transformation was studied as a function of temperature and uniaxial stress applied on (110) and (001) surfaces. Surface relief was observed optically several degrees above the bulk transformation determined ultrasonically. Atomic force measurements of the surface relief show clear evidence of the surface transformation at slightly higher temperatures, and the height of the thermally induced surface relief band increased from 20 nanometers to 3 microns when the band is fully developed. The stress induced bands are smaller and have different orientations. These measurements clearly show that the transformation emanates at the surface near regions of high local strain. Uniaxial stress applied along the  direction has a profound effect on the martensitic phase transformation temperature and the ultrasonic studies yield a value of dMs/dT = 0.4 K/MPa. These results will be compared with recent neutron diffraction of the uniaxial stress dependence of the phonon behavior in Ni62.5Al32.5 and thermal expansion studies.
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