Mechanical properties of cBN-Al composite materials

The relationship between microstructure and mechanical properties for a wide range of composite materials based on polycrystalline cubic boron nitride and aluminium as a binder phase (PcBN-Al) has been examined. The PcBN-Al composites were made using high-pressure, high-temperature (HPHT) sintering methods, yielding materials with grain sizes of cBN between 2 and 20 mu m and an initial amount of Al binder between 15 and 25 vol.%. Hardness ranged between 15 and 40 GPa, while fracture toughness and strength were between 6.4-8.0 MPa m(1/2) and 355-454 MPa, respectively. Fractography was employed to investigate the large scatter in fracture strengths and correlate fracture strength with fracture toughness through the size of the fracture origins. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.