Thermodynamic Studies and Magnetic Ordering of Ni-Cr Alloys Close to the Critical Composition

Abstract

We report measurements of the specific heat capacity and the thermal expansion for Ni-Cr alloys in the vicinity of the magnetic ordering temperature TM and at lower temperatures. No evidence of a contribution due to the magnetic ordering is found in the specific heat capacity and only the indication of a small contribution in the thermal expansion near to T M for an Ni 11 at. % Cr alloy. A significant contribution of magnetic origin is seen for both quantities at lower temperatures. Values for the magnetic Grlineisen parameter yi, are derived from the specific heat capacity and thermal expansion data and compared with values of dIn TM/d In V obtained from direct easurements of dTM/dP. Both yi, and - d In TM/d In V are large and negative for weakly ferromagnetic alloys but differ numerically, whereas for paramagnetic alloys yi, is large and positive.