How Does Irradiation Affect Yield Strength in BCC and FCC Structures?

[matt222]

I have a question about source hardening: what is the reason for a decrease on the yield strength in the case of the 1-(Un-irradiated) Body centre cubic (bcc) 2- (irradiated) face centre cubic (fcc)

 

[Astronuc]

I have a question about source hardening: what is the reason for a decrease on the yield strength in the case of the 1-(Un-irradiated) Body centre cubic (bcc) 2- (irradiated) face centre cubic (fcc)

What is the context of the question, i.e., what is the environment of the materials? And what type of material - steel?