Oxidation behavior of plasma sintered beryllium–titanium intermetallic compounds as an advanced neutron multiplier

Abstract

Beryllium intermetallic compounds (beryllides) such as Be12Ti are very promising candidates for advanced neutron multiplier materials in a demonstration fusion power reactor (DEMO). However, beryllides are too brittle to be fabricated either into pebble-type or rod-type shapes via conventional methods (i.e. arc melting and hot isostatic pressing). We have proposed a plasma sintering technique as a new method for beryllide fabrication, and our studies on the properties of plasma sintered beryllides are ongoing.In the present work, the oxidation properties of plasma sintered beryllides were investigated at 1273K for 24h in a dry air atmosphere to evaluate the high temperature properties of this material. Thermal gravimetry measurements indicate that specimens with larger fractions of Be12Ti phase corresponding to samples that have been sintered for longer time periods, exhibit superior oxidation properties.Our evaluation of the oxidation behavior of each phase in our beryllide samples is as follows: Be12Ti and Be17Ti2 both have good oxidation resistance, owing to the formation of dense and protective scales, while the Be and Be2Ti phases are mainly responsible for thermal-gravimetry (TG) weight gains, which is indicative of severe oxidation. We attribute the degradation in oxidation resistance specifically to Be2Ti that transforms into TiO2, and also find this phase to be the cause of deterioration in the mechanical properties of samples, owing to cracks near Be2Ti phase conglomerates.