Kinetics analysis of mechano-chemically and thermally synthesized Cu by Johnson–Mehl–Avrami model

In this paper, the isothermal reduction process kinetics of Cu2O with carbon under high vacuum for a non-activated sample and mechanically activated samples has been studied. The influence of milling time on the apparent activation energy was analyzed using Johnson–Mehl–Avrami (JMA) model. In order to gain a deeper insight into the possible mechanisms that govern mechanochemical solid-state reduction of Cu2O, the kinetic of the process was investigated using a similar model. It was found that in temperature range of 550–650 °C, the rate determining step of the thermal reduction is chemical reaction. But in the range of 650–750 °C, the rate determining step seems to be diffusion. Analyzing the relevant experimental results and comparison of the thermal and mechanochemical reduction kinetics showed that the mechanical activation induced by milling may decrease the required reaction activation energy by increasing defect sites. However, it appears that the thermal and mechanical activation induce different transformation rates, but the transformation paths are the same.