  Ti3SiC2 is a potential structural material for nuclear reactor applications.
However, He irradiation effects in this material are not well understood,
especially at high temperatures. Here, we compare the effects of He irradiation
in Ti3SiC2 at room temperature (RT) and at 750 {\deg}C. Irradiation at 750
{\deg}C was found to lead to extremely elongated He bubbles that are
concentrated in the nano-laminate layers of Ti3SiC2, whereas the overall
crystal structure of the material remained intact. In contrast, at RT, the
layered structure was significantly damaged and highly disordered after
irradiation. Our study reveals that at elevated temperatures, the unique
structure of Ti3SiC2 can accommodate large amounts of He atoms in the
nano-laminate layer, without compromising the structural stability of the
material. The structure and the mechanical tests results show that the
irradiation induced swelling and hardening at 750 {\deg}C are much smaller than
those at RT. These results indicate that Ti3SiC2 has an excellent resistance to
accumulation of radiation-induced He impurities and that it has a considerable
tolerance to irradiation-induced degradation of mechanical properties at high
temperatures.
