Influence of hydrostatic pressure on martensitic transformation and strain behavior for Co₅₂V_29+xGa_19−x Heusler alloys

In the present work, polycrystalline Co₅₂V₂₉+_xGa_19-x(0 ≤ x ≤ 2) Heusler alloys have been prepared. The related experimental results confirm that each sample undergoes a first-order martensitic transformation (MT) from the L2₁ cubic austenitic state to the D0₂₂ tetragonal martensitic state. With increase of V concentration, both transformation temperature and strain are heightened simultaneously, thus giving rise to an increment of transition entropy change \(\left( {\Delta S_{{{\text{tr}}}} } \right)\). In addition, the influence of hydrostatic pressure on MT and transition strain have been also carefully studied. With increase of pressure, the transformation temperatures of these samples move to high values apparently, but their reversible strain only exhibit a slight enhancement and quickly approach the saturated values. For different compositions, however, there is no obvious difference in the rate of transformation temperature change with pressure. Such a behavior opens up the potential applications of the functional properties associated with the hydrostatic pressure-induced MT for this system.