A neutron absorbent material and its elaboration process

A novel neutron absorbent composite material comprises a homogeneous boron carbide (B4C) matrix, in which are homogeneously dispersed sized clusters of HfB2, TiB2 and/or ZrB2. Production of the above composite material involves homogeneously mixing B4C powder of less than 5 microns average particle size with the sized boride clusters, and hot pressing (uniaxially or isostatically) the mixture to a density greater than 90% of theoretical density. It can be used in nuclear reactors such as PWRs and fast neutron reactors. The boride clusters improve the behaviour (cracking resistance) under irradiation of the B4C, while maintaining the maximum possible neutron absorption efficiency. 4 figs