Yuli Li

The dynamic properties of B4C/6061Al neutron absorber composites fabricated by power metallurgy

ABSTRACT The dynamic compression properties of B4C/6061Al neutron absorber composites (NACs) with three B4C volume fractions (20–40%), fabricated by power metallurgy, were studied. Compression tests were conducted at strain rates ranging from 760 to 1150 s−1, using a split Hopkinson pressure bar. The damage mechanism was studied through microstructural analysis. Results show that the B4C particles exhibited a uniform distribution in the 6061Al matrix. The NACs dynamic strength was found to improve with increasing quantities of B4C particles, and with strain rate. The damage mechanisms include particle fracture and interface debonding. Dislocation pile-up was observed at grain boundaries and at the interface between particles and the matrix. A constitutive model under dynamic compression was developed based on the Johnson–Cook model. This paper is part of a thematic issue on Nuclear Materials.

Understanding micro-diffusion bonding from the fabrication of B 4 C/Ni composites

A Ni-B4C macroscopic diffusion welding couple and a Ni-15wt%B4C composite fabricated by spark plasma sintering (SPS) were used to understand the micro-scale diffusion bonding between metals and ceramics. In the Ni-B4C macroscopic diffusion welding couple a perfect diffusion welding joint was achieved. In the Ni-15wt%B4C sample, microstructure analyses demonstrated that loose structures occurred around the B4C particles. Energy dispersive X-ray spectroscopy analyses revealed that during the SPS process, the process of diffusion bonding between Ni and B4C particles can be divided into three stages. By employing a nano-indentation test, the room-temperature fracture toughness of the Ni matrix was found to be higher than that of the interface. The micro-diffusion bonding between Ni and B4C particles is quite different from the Ni-B4C reaction couple.