Characterization of microstructure and hardening of B4C/6082Al neutron absorbing composites irradiated by He ions

Evaluating the performance of B 4 C/6082Al composites that are expected to be used for neutron absorption in spent fuel pools (SFPs), especially under He-induced damage, is the key to ensuring the subcritical safety of spent fuel. The composites prepared by cyclic extrusion compression (CEC) without sintering were irradiated by 100 keV He ions at room temperature (RT) with a fluence of 6 × 10 16 ions/cm 2 . The composites prepared by hot pressing (HP) were used as control group to evaluate the irradiation resistance under the same irradiation parameters. The irradiation damage and irradiation-induced hardening of the 6082Al matrix and B 4 C reinforcement of the HP- and CEC-consolidated composites were compared by transmission electronic microscopy (TEM) and nanoindentation measurements. The average diameters of the He bubbles in the 6082Al matrix of the HP- and CEC-consolidated composites were ∼1.51 and ∼1.20 nm, respectively. The irradiation hardening degree of the HP-consolidated composites (matrix: ∼97.8%, reinforcement: ∼68.0%) was significantly higher than that of the CEC-consolidated composites (matrix: ∼34.0%, reinforcement: ∼50.5%). Compared with the composites prepared by HP, the fine-grained composites prepared by CEC showed improved irradiation resistance in terms of smaller He bubble size and less irradiation hardening. This study provides a reference for the preparation of irradiation-resistant composites for nuclear industry applications.