Evolution of supersaturated metastable phase in sputtered Cu–Fe alloy

Equilibrium phase diagram of Cu and Fe predicts extremely limited solid solubility at room temperature due to their positive heat of mixing. However, nonequilibrium processing techniques can create supersaturated solid solutions with metastable phases. Here, we report depositions of equal atomic percentages of Cu and Fe at different substrate temperatures. Phase evolutions have been observed in Cu–Fe to occur significantly with variation in temperature. Cu–Fe films deposited at room temperature exhibited both face centered cubic and body centered cubic (BCC) structures, while higher substrate temperature (up to 400 °C) led to the dominance of BCC structures. Changes in precipitation behavior of Cu and Fe with temperature have also been reported. This study provides insights on tailoring the supersaturated metastable phases by changing the substrate temperatures.