The helium embrittlement with helium injection by cyclotron and the irradiation embrittlement with neutrons by JMTR were compared in Fe-25% Ni-15% Cr alloys and Fe-40% Ni-15% Cr alloys with and without intermetallic compound strengthening, and in the MA 956 alloy. The results are summarized as follows: 1. (1) For helium-injected austenitic alloys precipitation-hardened by γ′ or γ″ to their highest strength, the total elongation almost becomes zero even for a very low helium level of 5-10 at ppm. 2. (2) For neutron-irradiation specimens, the embrittlement is also prominent for the specimens with highest tensile strength. The embrittlement may be caused primarily by helium from 10B(n, α) reactions. 3. (3) Addition of 0.25% Ti to the Fe-25Ni-15Cr alloy slightly suppresses the helium embrittlement in the case of neutron irradiation, but not in the He-injected case. 4. (4) The MA 956 alloy is found quite resistant to helium embrittlement even for high helium levels of 670 atppm.
ASJC Scopus subject areas