c$)$ When austenite containing about $0\mathrm{.}8wt\%C$ is cooled below the $A1$ temperature, pearlite is formed. Explain carefully the microstructural characteristics and how pearlite is formed. $(2$p$)$

d$)$ With respect to particle coarsening, give one example of how you could design a material for high temperature. Motivate your answer. $(2$p$)$

$6.8p$

Diffusionless transformations $(8$p$)$

a$)$ Plastic deformation of $BCC$ metals at low temperatures or high strain rate tends to result in formation of deformation twins. It is said that the growth of those twin shows similarities with martensitic phase transformations. Discuss what these similarities are. $(3$p$)$

b$)$ At a point upon martensite growth, the thickening of the plate is prevented by the austenite, why? Motivate your answer $(2$p$)$