Effect of uniform pressure on deformation-induced processes was studied in Ti-Ni and Cu-Al-Ni alloys that exhibit thermoelastic martensitic transformations. It was shown that in the Ti52.5Ni47Fe0.5 alloy under a shear stress of 65 MPa, an applied pressure decreases the characteristic martensitic temperatures Ms, Mf , As, and Af by 5-7, 1.5-2, 3-4, and 9-10 K, respectively. For the Ti52Ni47.5Fe0.5 alloy, to initiate the accumulation of deformation in cooling, the pressure must be increased upon the realization of the B2 R transformation and decreased in the course of the R B19' transition. Another situation is observed in the Ti50.1Ni49.9 alloy, in which the shape-memory effect is realized due to only the B19' B2 transformation; namely, the applied pressure in it decreases the As and Af temperatures by about the same value equal to 6 K. In this alloy, an increase in the pressure from the atmospheric pressure to 200 MPa can initiate shape restoration. As was exemplified by the β1 single crystal (Cu-13.2% Al-4% Ni), the pressure applied can both stimulate the realization of shape memory effects and cause a change in the temperature of their development. This can be realized by increasing the pressure in cooling and decreasing it in heating. In the case of the transitions B2 B19' in the Ti-Ni alloys and β1 in the Cu-Al-Ni alloy, the temperature shifts were found to be larger by a factor of 3-4 (on average) than the estimates obtained taking into account only the volume effect of martensitic transformation.
|Number of pages||6|
|Journal||Fizika Metallov i Metallovedenie|
|Publication status||Published - 30 Oct 2003|
Scopus subject areas
- Metals and Alloys
- Condensed Matter Physics