Mechanical Properties of Al₂O₃/TiC/Ni FGMs Doped with WC/Co

Abstract

The Al₂O₃-WC-Co/TiC/Ni/TiC/Al₂O₃-WC-Co FGMs with a symmetrically graded structure were fabricated by SHS/HIP. It is possible to induce the strong residual compressive stress in the outer ceramic layers of the ceramic/metal/ceramic symmetric FGMs due to the thermal expansion mismatch between the outer and inner layers. The doping of WC-Co into the outer Al₂O₃ layers further increased the residual stress comparing with the Al₂O₃/TiC/Ni/TiC/Al₂O₃ system. The toughness and the strength of the outer layer increased to 13.1MPam^1/2 and 950MPa by doping 20vol% of WC-Co, respectively. Stress analysis was carried out for the macro and micro structures of FGMs by means of X-ray diffraction method and finite element method. The correlation between the surface stress and the mechanical properties was discussed.