The Vickers hardness of polycrystalline { \gamma}-B was measured using a diamond indentation method. The elastic properties of polycrystalline { \gamma}-B (B=213.9 GPa, G=227.2 GPa, and E=503.3 GPa) were determined using ultrasonic measurement at ambient condition. Under the loading force up to 20 N, our test gave an average Vickers hardness in the asymptotic-hardness region of 30.3 GPa. The average fracture toughness was measured as 4.1MPa m1/2. Additionally, We also measured the hardness and elastic properties of polycrystalline { \beta}-B and PcBN for comparison. The hardness and elastic properties for polycrystalline { \gamma}-B was found to be very close to that of PcBN. Our results suggest that the polycrystalline { \gamma}-B could be a superhard polycrystalline material for industrial applications.
Categories: cond-mat.mtrl-sci