A Study on Ultra-Hard AlMgB 14 Modified by TiB 2 and Ni 3 Al

AlMgB14 is a very hard and brittle material which need be modified for utilizing as cutting tool materials. In present study, TiB2 and Ni3Al were used to strengthen and toughen AlMgB14 material. The microstructure of the AlMgB14-TiB2-Ni3Al composites was analysized by scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) and an X-ray diffractometer (XRD). The hardness and fracture toughness of the AlMgB14-TiB2Ni3Al composites were also examined. The results showed that the major phases in AlMgB14-Ni3Al composites were TiB2, AlMgB14, MgAl2O4 , Ni3Al and NiAl. With the increasing of the amount of Ni3Al, more intergranular fractured features can be found in the fractured surface of the composites, the hardness and fracture toughness of the composites were both decreased comparing to the synthesised AlMgB14. The AlMgB14-TiB2-4wt.% Ni3Al composite has a hardness of 28.1 Gpa and a fracture toughness of 3.14 MPa·m1/2.