Synthesis and radiation damage tolerance of Mo0.75W0.25AlB solid solution for nuclear fusion reactor applications.

MAB phases (M = transition metal, A = aluminium (Al), B = boron (B)), a new family of nano-laminated ternary transition metal borides with an excellent combination of functional and structural properties, are currently being investigated as potential radiation shielding materials in nuclear fusion reactors. Here, we report the fabrication of a solid solution MAB phase Mo 0.75 W 0.25 AlB (Mo - molybdenum, W - tungsten), in the form of dense and high purity pellets, synthesised for the first time using a reactive hot-pressing method. The shielding and irradiation damage properties of the material were also evaluated. Monte Carlo N-Particle (MCNP) calculations showed that W doping in the MoAlB phase is likely to enhance the shielding capacity against neutrons and gamma rays of different energies. The experimental damage tolerance of Mo 0.75 W 0.25 AlB to silicon ion (Si+) irradiation indicated that this solid solution compound has a high resistance to crack formation and other radiation damage effects compared to that of pure MoAlB. Thermal annealing of the amorphous Mo 0.75 W 0.25 AlB layer formed by irradiation showed that the damaged structure easily recrystallizes at high temperatures, completely returning to the virgin state. The results show that this solid solution should be considered as a promising candidate material for radiation shielding components. • A high density and purity Mo 0.75 W 0.25 AlB solid solution was synthesised by sintering at 1100 °C. • Mo 0.75 W 0.25 AlB exhibits excellent shielding capacity against gamma rays and neutrons of different energies. • Unlike MAX phases, no cracks or voids were observed on the surface of the amorphous MAB phase. • The radiation-induced amorphization of the solid solution was almost completely recovered by thermal annealing at 700 °C. [ABSTRACT FROM AUTHOR]