Co-Fe-Gd (Cobalt-Iron-Gadolinium)

Abstract

mal sections that agree reasonably well with the limited experimental results available. The isothermal section at 1050 C determined by [1990Ati] (reviewed in [1992Rag]) shows that the pairs Fe17Gd2-Co17Gd2 ,F e 3Gd-Co3Gd, and Fe2Gd-Co2Gd form Binary Systems continuous solid solutions. These solutions are denoted here by M17Gd2 ,M 3Gd, and M2Gd, respectively. [1995Liu] evaluated the thermodynamic properties of this ternary system, The Co-Fe phase diagram was reviewed by [1993Nis]. The fcc phase forms through a peritectic reaction at 1499 using the experimental results of [1990Ati]. [1995She] studied the phase equilibria in this system by Cbetweenbccandliquid.TheCoandFeformacontinuous fcc solid solution () over a wide range of temperature, the diffusion-couple technique and presented five isothermal sections at 1200, 1050, 1000, 950, and 900 C. Tie-line comwhich transforms to bcc () below 985 C. An order-disorder transformation occurs in the equiatomic phase at 730 C positions were determined for the pairs -M17Gd2 ,M 17Gd2M3Gd, M3Gd-M2Gd, M17Gd2-Co5Gd, Co5Gd-Co7Gd2, and and the CsCl-type ordered phase exists over a wide composition range below this temperature. The Co-Gd phase diagram Co7Gd2-M3Gd. Using the experimental data of both [1990Ati] and [1995She], [1998Su] optimized the thermodywas calculated by [1995Liu]. There are seven intermetallic phases in this system: Co17Gd2 ,C o 5Gd, Co7Gd2 ,C o 3Gd, namic properties of the ternary system and recalculated the ternary equilibria at 1200, 1050, 1000, 950, 900, and 427 Co2Gd, Co3Gd4, and CoGd3. With the exception of Co17Gd2, theyformthroughperitecticreactions.Thefinalsolidification C. The calculated and experimental tie-line compositions agree reasonably well. The computed isothermal sections at