The effect of He ions irradiation on the micro-structure and property of CLF-1 steel

The TEM image of the CLF-1 steel after He2+ irradiation with the fluence of 1 × 1018/cm2(a)the cross-section morphology image (b) the atomic short-range ordered area in A region of a (c) the carbide particle in B region of a (d) the SAED pattern of the carbide particle in Fig. a gives a sectional morphology of the steel. It shows a He bubble layer with the thickness about 300 nm formed at the end of ion range. Meanwhile, it can be seen that the number of dislocation loops in the damage layer decreased. Fig. b is the magnified image of region A in Fig. a and shows that amorphous region with long-range disordered was formed locally in the damage layer of CLF-1 steel. It was mainly caused by the higher free energy of the crystal phase which may promoted the transition from crystal to amorphous. Fig. c is the carbide particles in the matrix of CLF-1 steel, respectively. Fig. d is the corresponding selected area electron diffraction pattern of the carbide particles. Some carbon particles with a diameter of dozens of nanometers could be seen in the matrix, while in the irradiated damaged layer, these were almost invisible which indicated that the carbide particles had a trend of decomposition caused by the irradiation.259