Effect of added Cu on disorder-order transformation of L1/sub 0/-FePt

Abstract

The L1/sub 0/-FePt ordered phase is formed at lower annealing temperature by addition of Cu. FePtCu films start ordering at 300/spl deg/C or a lower temperature, whereas FePt and FePtAg films are still disordered alloys after annealing at 300/spl deg/C. The results of X-ray diffraction indicate that FePt and the added Cu form an FePtCu ternary alloy, whereas FePtAg decomposes into FePt and Ag phases in the disorder-order transformation. From thermodynamic considerations, it is concluded that reduction of the ordering temperature of FePt is due to the formation of an FePtCu solid solution.