Thermodynamic calculations of phase equilibria of Co-Cr-Pt ternary system and magnetically induced phase separation in the FCC and HCP phases

The calculations of phase equilibria of the Co-Cr-Pt ternary system have be en carried out based on the thermodynamic assessments of Co-Cr, Co-Pt and C r-Pt binary systems by the calculation of phase diagram technique. The Gibb s energies of the liquid, FCC, BCC and HCP solution phases were approximate d by a sub-regular solution model, while those of sigma and Cr3Pt phases we re approximated by a compound energy model. Almost all the experimental inf ormation on each sub-system has been well described by the present set of t hermodynamic parameters. A critical calculation of the magnetically induced miscibility gap between the ferromagnetic HCP and the paramagnetic HCP pha se has been conducted, where the two-phase separation has been found at the Curie temperature. The Cr content in the ferromagnetic HCP phase increases and the width of the two-phase separation becomes narrower with increasing Pt content. The present calculations would be useful for the design and de velopment of the perpendicular magnetic recording media. (C) 2001 Elsevier Science B.V. All rights reserved.