Answer:
a. False
b. True
c. False
d. True
e. True
Explanation:
The questions doesn't specify but it look most likely as a true/false question as most of its content are statement that are true/false
Martensitic transformation takes place first internally at the surface and it doesn't only occur in Fe-C system. It can occur in system like Cu-Al, Au-Cd, Fe-Ni etc
Certain materials can age harden at room temperature. Most material do harden at room temperature.
Pure metals cannot be age hardened. So, the statement from the question is False.
Tempering of martensitic steel increases its ductility; tempering of martensitic steel allows it to regain ductility.
Over-aging can occur when the aging temperature is large enough such that incoherent precipitates form.
