The effect of hydrostatic pressures on martensitic phase transformations in near-equiatomic Ti-Ni shape-memory alloys has been investigated up to 1.5 GPa. The relative volume changes δVc/V and the entropy changes δSc have also been determined at atmospheric pressure. Supposing that the volume derivative of the elastic energy differs from zero at the martensite start (and austenite finish) temperatures as well, that is e0 ≠ 0, and that the Clausius-Clapeyron equation is valid for the equilibrium transformation temperature T0, it was shown that the dissipative energy terms were approximately zero for the B2-R transition. For the R → B19′ transformation this energy was independent of pressure, while for the reverse transformation it had a defmite pressure dependence. The pressure derivatives of elastic energy em (which corresponds to the martensite finish or austenite start) and e0 are similar in both directions for the R-B19′ transformations, while for the B2-R transition it is negative for e0.
|Number of pages||16|
|Journal||Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties|
|Publication status||Published - Jan 2002|
ASJC Scopus subject areas
- Chemical Engineering(all)
- Physics and Astronomy(all)