Thick Cobalt $($Co$)$ and Titanium $($Ti$)$ metal plates are attached against each other

$(=$semi$-$infinite 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. $($NB$.$ Mark clearly the compositions of the phases at all

interfaces!$)$ In addition, please explain shortly how the structure of the diffusion couple is

changed if the temperature is then decreased down to $650C?(4+1p)$

Figure $3$ Ti$-$Co binary phase diagram