Development of novel ultra-hard materials composed of 5d transition-metal nitrides using high-pressure methods

Abstract

Development of novel ultra-hard materials exceeding WC-Co cemented carbides is strongly desired because demands for difficult-to-machine materials increase. We have been challenging the synthesis of new hard materials composed of 5d transition-metal nitrides under high pressure. Then, we have realized the effectivity of high-pressure metathesis reaction for synthesizing 5d transition metal nitrides. Rhenium nitride crystals with MoS2 structure was newly synthesized in the metathesis reaction. The tantalum nitride with WC structure, indicating a high vicker's hardness (HV > 30 GPa) are also synthesized under the pressure of 5.5 GPa.