2. Interface migration Following is a solid composed of A and B atoms. The matrix is B-rich (almost all B atoms). The a matrix is A-rich (the concentration of A atoms is greater than the concentration of B atoms.) to Which two processes are necessary for the growth of the phase? Following are the Gibbs free energy curves for the a and phases. G Ed GB Xi Xe (b) Xi represents the concentration of B atoms at the interface. Draw on the graph the quantity of the driving force of migration of B atoms across the interface. (c) On the following graph, indicate with a dot (on the Gibbs free energy curve of the a matrix) the equilibrium concentration of B atoms at the interface. G2 G Xg- GB (d) On the graph in part (c), show graphically why the driving force of migration is zero in equilibrium.