Question

Explain why BCC metals undergo a brittle to ductile transition and fcc metals do not in terms of dislocations and the metals' crystal structures ?

Please explain in a good words!!! Thanks

Answer 1

Solution :-

The ductile-brittle transition is present in the BCC metals which becomes brittle at low temperature and high stress. While the FCC metals remain ductile at low temperatures

The process of ductile failure or the brittle failure depends on the amount of stress provided.

In FCC metals the stress required to move the dislocations is not more temperature dependent therefore dislocation movement remain high even at low temperatures and therefore material or metal remain relatively ductile. On the other hand in the BCC metals the stress required is mainly dependent on the temperature. Therefore the mode of the failure changes from plastic flow at high temperature to brittle fracture at low temperature.