$(0\mathrm{.}2$ p$)$ Thick gold $(Au)$ and titanium $($Ti$)$ metal plates are attached against each other $(=$semiinfinite diffusion couple$)$ at the temperature of $1000C.$ Based on the phase diagram $($see Fig. $3)$ draw the structure of the diffusion couple and the composition profiles for both components, when sufficient amount of time has elapsed so that local equilibria is achieved in all interfaces.

Figure $3.$ Ti$-$Au binary phase diagram