Enhanced Metastable Solubility by Ball Milling of Rapidly Solidified Cu-Co-Mn Ribbon

Enhancement of solid solubility in binary immiscible Cu-Co system due to thermodynamic contribution from ternary Mn addition and kinetic contribution from use of rapidly solidified ribbons as the precursor of ball milling has been investigated. The impact of ternary addition on the binary system’s free energy change at various concentrations and grain size has been estimated by employing the thermodynamic model proposed by Miedema incorporating appropriate modifications for ternary addition. The solid solubility results obtained from x-ray diffraction analysis of the rapidly solidified ribbons have been compared with the results obtained by the thermodynamic calculation, and an attempt has been made to identify the potential attributes contributing to the mechanically induced solid solubility in the immiscible systems. High-resolution transmission electron microscopy (HRTEM), differential thermal analyzers (DTA) and x-ray diffraction (XRD) have all been used to characterize the phase advancement during rapid solidification, mechanical alloying and isothermal annealing. Using a superconducting quantum interference device magnetometer (SQUID), magnetic characteristics have been investigated. Following annealing in the ball-milled Cu-Co-Mn alloy at 550 °C for 1 h, the ideal combination of magnetic characteristics was achieved.