The figure given below shows the molar free energy$-$composition diagram for the A$-$B system at

temperature T$1.$ Imagine that a block of $$ with composition $(1)$ is welded to a block of $$ phase with

composition $(2).$ By considering the chemical potentials of the A and B atoms in both the $$ and $$ phases

predict which way the atoms will move during a diffusion anneal at T$1.$ Show that this leads to a reduction

of the molar free energy of the couple. Indicate the compositions of the two phases when equilibrium is

reached.