Figure $2$ shows the $Ni-Ti($Nickel$-$Titanium$)$ phase diagram. With the help of the

diagram answer following questions:

a$)$ What can you say about the solubility of Nickel to Titanium and Titanium to Nickel at

temperatures from $600C$ to $900C?(1$p$)$

b$)$ Explain the equilibrium $(D_{\text{L}\text{i}\text{q}}=D_{\text{s}\text{o}\text{l}\text{i}\text{d}}=)$ solidification $($i$.$e$.$ the compositions and

amounts of phases as a function of temperature$)$ from $1800C$ to $600C$ when the nominal

composition of the alloy is Ti$80$Ni$20($at$-\%).$ You need to include in your answer at least

following details. i$)$ What is the composition of the solid phase when first solid crystals

nucleate from the liquid and at what temperature this occurs? ii$)$ What is the composition

of the liquid just before it is completely solidified? iii$)$ What phases are in equilibrium at

$850C$ and $750C,$ what are the compositions and relative amounts of the phases at these

temperatures? $(4p)$