1991 Volume 32 Issue 4 Pages 305-307
An alloy Fe0.7Ni0.3 has been studied under high pressure up to 45 GPa by X-ray diffraction and an electric resistance measurement. The bcc α′-martensitic phase is transformed to a fcc γ-austenitic phase at 8 GPa at room temperature. This transition is accompanied by the volume reduction of 0.17×10−6 m3/mol and a large resistance increase. The decrease of the austenite-start temperature, As, from 623 K at ambient pressure to room temperature at 8 GPa gives the mean value of dAs⁄dP=−40.4 K/GPa. The entropy change of ΔS=4.23 J/mol·K is obtained for the reverse martensitic transition.