During the annealing process, which stage has the most dramatic change in disloc

Question

During the annealing process, which stage has the most dramatic change in dislocation density? Recovery Recrystallization Grain growth They are about the same in terms of changes to dislocation density What would happen to room temperature properties if you were to plastically deform a material (like by rolling in a mill) when the temperature of the material were held above 60% of the melting temp in Kelvin? (properties would be measured after the sample cools back down to room temp). this process is known as "hot working". The material will get significantly stronger and less ductile The material will get significantly stronger and more ductile The strength and ductility will stay about the same The strength will decrease significantly but ductility will increase significantly The strength and ductility will both decrease significantly. The driving force for grains getting larger when exposed to elevated temperatures is based on Surface energy (small grains have higher energy) Large grains are drawn to the higher temperatures and small grains are repelled Crystallographic orientation Dislocation density (dislocations store energy)

Explanation / Answer

7.Recrystallization, where new strain-free grains nucleate and grow to replace those deformed by internal stresses

option b) Recrystalization

8. Hot working improves the engineering properties of the workpiece because it replaces the microstructure with one that has fine spherical shaped grains. These grains increase the strength, ductility, and toughness of the material

Option b , stronger and more ductile

9. Reduction in the internal energy can only be achieved by reducing the total area of grain boundary.

there is a thermodynamic driving force for the total area of boundary to be reduced. If the grain size increases, accompanied by a reduction in the actual number of grains per volume, then the total area of grain boundary will be reduced.

option a ) surface energy

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