We have developed a new material for neutron shielding applications where space is restricted. W 2 B is an excellent attenuator of neutrons and gamma-rays, due to the combined gamma attenuation of W and neutron absorption of B. However, its low fracture toughness (∼3.5 MPa) and high melting point (2670 • C) prevent the fabrication of large fully-dense monolithic parts with adequate mechanical properties. Here we meet these challenges by combining W 2 B with a minor fraction (43 vol.%) of metallic W. The material was produced by reaction sintering W and BN powders. The mechanical properties under flexural and compressive loading were determined up to 1900 • C. The presence of the ductile metallic W phase enabled a peak flexural strength of ∼950 MPa at 1100 • C, which is a factor of 2-3 higher than typical monolithic transition-metal borides. Its ductile-brittle transition temperature of ∼1000 • C is typical of W-based composites, which is surprising as the W phase was the minor constituent and did not appear to form a fully continuous network. Compression tests showed hardening below ∼1500 • C and significant elongation of the phase domains, which suggest that by forging or rolling, further improvements in ductility may be possible.

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