Phase relations in the LaB6-MoB2 system

LaB 6 -MoB 2.2 alloys have been prepared at 2600°C in high-purity helium in a vacuum induction furnace. As found by microstructural analysis and x-ray diffraction, the components of this system form a eutectic. The microstructure of the eutectic has been studied. MoB 2.2 is shown to undergo a transformation during cooling, with the precipitation of submicron-sized Mo 2 B 5 and α-MoB particles. For this reason, its microhardness increases with an increase in the melting temperature of the alloys because the diffusion rate rises with temperature.