High-pressure synthesis of cubic BN using Fe–Mo–Al and Co–Mo–Al alloy solvents

The pressure and temperature regions of cubic BN formation were determined using Fe–Mo–Al and Co–Mo–Al ternary alloys as synthetic solvents of cubic BN. The alloy compositions employed in the present study were (in weight percent) Fe60.14–Mo36.86–Al3 and Co57.6–Mo38.4–Al4. The cubic BN was successfully synthesized at minimum pressure of about 4.4 GPa and temperature of about 1250 °C. Pressure and temperature of cubic BN synthesis were decreased drastically by small amount of Al addition into Fe–Mo or Co–Mo alloy solvents. The growth of cubic BN was started at the interface between the molten alloy and the source hexagonal BN. In the present study, we proposed that Fe–Mo and Co–Mo work as solvent of B and N atoms and Al acts as a nucleation agent of cubic BN.

Research highlights
► Cubic BN was synthesized using Fe–Mo–Al and Co–Mo–Al solvent.
► Cubic BN was precipitated at about 4GPa and 1300 °C.
► Synthesizing pressure of cubic BN was lowered using alloy solvent.
► Effect of Al to the nucleation of cubic BN was discussed.