During the annealing process, which stage has the most dramatic change in dislocation density?

a$.$ Quenching

b$.$ Recovery

c$.$ Recrystallization

d$.$ Grain growth

e$.$ All stages about the same in terms of changes to dislocation density

Which of the following are common characteristics of thermoset polymers?

a$.$ Heavily networked or cross linked structures.

b$.$ Linear or slightly branched long chain molecules.

c$.$ Soften on heating and harden on cooling.

d$.$ Often recycled back into the same or similar applications.

What impact would substituting $C{a}^{2+}$ ions for zirconium ions $($i$.$e$.$ adding an impurity of calcium in the form of CaO $)$ in a $Zr{O}_2$ ceramic have on the material in terms of defects?

a$.$ For each $C{a}^{2+}$ substitution, one $O^{2-}$ vacancy would form

b$.$ For each $C{a}^{2+}$ substitutions, one $O^{2-\text{i}\text{n}\text{t}\text{e}\text{r}\text{s}\text{t}\text{i}\text{t}\text{i}\text{a}\text{l}\text{w}\text{o}\text{u}\text{l}\text{d}\text{f}\text{o}\text{r}\text{m}}$

c$.$ For each $C{a}^{2+}$ substitution, one Frenkel defect would form for oxygen

d$.$ For each $C{a}^{2+}$ substitution, one Schottky defect would form for $Zr$ and $O$

The addition of a phosphorous $($P$)$ impurity to otherwise pure silicon $($Si$)$ will

a$.$ Decrease conductivity due to additional scattering of electrons due to the impurity

b$.$ Create an additional allowable energy level inside the band$-$gap called a donor level

c$.$ Create an extrinsic semiconductor with holes being the majority charge carrier

d$.$ Transform the silicon from a semiconductor to an insulator.

e$.$ Provide a mechanism to stabilize the cubic phase of silicon.

What do you expect to happen when heating a typical thermoplastic polymer?

a$.$ It will soften considerably and then eventually melt

b$.$ It will remain rigid and eventually degrade $($burn$)$ and not melt

c$.$ If it was first cold worked, it will go through recovery, recrystallization, and grain growth

d$.$ Depends on the phase diagram and the specific phases present

e$.$ Heating will cause any martensite present to temper which will slightly increase ductility