Initial investigation of B4C–TiB2 composites as neutron absorption material for nuclear reactors

Abstract

In this study, a specifically designed B4C–TiB2 composite with the typical microstructural feature of a TiB2 network (cages) that encapsulates a B4C matrix was fabricated by the molten-salt and spark plasma sintering (SPS) method. The finite-element (FE) calculation results show that the connected TiB2 cages constitute a thermally conductive network, which effectively improves the overall thermal conductivity of the composite; these results agree well with the experimental results. Moreover, the Vickers indentation results reveal that the TiB2 network (cages) can effectively impinge/block the propagation of cracks, which increases the composite toughness. The composite was subjected to helium (He) ion irradiation to simulate the situation in which the B4C–TiB2 composites serve as neutron absorption material, and for which case a high quantity of He atoms is produced by the B10 (n, α) Li7 nuclear reaction. According to the transmission electron microscopy (TEM) results, the interfaces between TiB2 and B4C act as effective sinks for He atoms, and are preferential nucleation sites for He bubbles. The theoretical and experimental results show that when the B4C–TiB2 composites serve as neutron absorption pellets in nuclear reactors, they exhibit a better resistance to their disintegration than pure B4C pellets. Consequently, the performance of the control rods of nuclear reactors can be improved.