Microstructure evolution and mechanical properties of B4C/6061Al neutron absorber composite sheets fabricated by powder metallurgy

Abstract B 4 C particle reinforced 6061Al matrix composites is interestingly used for neutron shielding due to its light weight and good strength and neutron absorbing. In this study, B 4 C/6061Al neutron absorber composite (B 4 C/6061Al NAC) sheet containing 30 wt% B 4 C particle was first fabricated by powder metallurgy (hot pressed sintering→extrusion→rolling), then its microstructure and mechanical properties were investigated. It was found that B 4 C particles distributed relatively homogeneously in the 6061Al matrix and the composite was mainly consisted of B 4 C, Al and Al 2 O 3 phases. B 4 C particles were found to be able to stimulate dynamic recrystallization (DRX) nucleation; restrain the grain growth; and reduce the preferential orientation of the aluminum grains. Moreover, under increasing deformation, amount of DRX was found to increases; the ultimate tensile and yield strength of the composites first increased and then decreased; while its elongation to fracture dropped. The decrease in strength was found to be due to the fracture of large B 4 C particles and the stress concentration in the locations between the B 4 C particle and the 6061Al matrix.