MOU PARTS A & B

For high technological industries, you evaluate metals and ceramics beyond the $Fe-C$ alloys to more costly applications.

A$.$ For one process, elect three alloying components for $Ti$ alloys to give alpha$-$gamma phase from an eutectoid reaction and another process, give three alloying components added to $Ti$ to give beta phase from a peritectic reaction. Be sure to describe each process in not more than three sentences.

B$.$ What alloying elements should you seek for stainless steel to have a bar or plate with an austenitic phase, as well as explain the reason or need for the phase.

C$.$ For a material of the hypersonic plane, liquid $Hf-Nb-Ti$ alloy infuses into a $B_{4}C$ packed bed and reacts to form a $Hf{B}_2-HfC-N{b}_3{B}_4-N{b}_{2}C-$TiC$-Ti{B}_2$ composite or the same boridecarbide precipitates embedded in a $Hf-Nb-Ti$ alloy matrix. Determine the mass of $Hf,Nb,$ and $Ti$ needed to give you $1kg$ of $N{b}_{2}C$ in metal matrix by using a $55at\%Hf-40at\%Nb-5at\%Ti$ alloy and adding $Nb$ to the alloy to achieve $15wt\%$ excess $Nb.$

D$.$ What three ceramics $($no metals$)$ must you use as a crucible for melting and hold an $Hf-Nb-Ti$ melt at $2600C?$

E$.$ A hafnium$-$niobium melt contained in a graphite or carbon crucible thick and $10cm$ inner diameter$)$ reacts to form an internal layer composed of $HfC$ and $NbC$ between the $Hf-Nb$ liquid and the internal, graphite crucible. The figure below gives the diffusion coefficients of carbon in $c\frac{m^2}{s}$ for $HfC,$TaC,$NbC$ and $ZrC.$

a$.$ Determine the carbon diffusion in TaC at $4100C.$

b$.$ Determine how much further carbon diffuses in TaC than $HfC$ for a ten hour hold in the furnace at $3273K.$

F$.$ From the Nb$-$C phase diagram, below, give the three$-$phase reactions for a eutectic, peritectic, peritectoid, congruent, and euctectoid reactions along with their respective temperatures at which they occur.