Simulation of the growth of copper critical nucleus in dilute bcc Fe–Cu alloys

The composition of Cu particles formed during isothermal aging in bcc Fe–Cu alloys was simulated using the Cahn–Hilliard nucleation theory and non-linear diffusion equation. Whereas Cu nuclei are almost pure Cu in low Cu content alloys, the Cu concentration in the nucleus is significantly less than unity in higher Cu content alloys. During aging it increases almost to unity at an early stage and the increase in particle radius follows. Experimental evidence in the latter alloys is yet to be obtained.