Microstructure and mechanical properties of ZrO₂/NiCr functionally graded materials

The microstructure and mechanical properties of ZrO₂/NiCr functionally graded materials (FGMs) fabricated by powder metallurgy are investigated experimentally. Microscopic examination exhibits that the material composition and microstructure of the FGMs vary gradually. The distributions of mechanical properties in the FGMs are obtained from the mechanical testing of homogeneous composite samples (non-FGM) with different volume fractions of ZrO₂. The experimental results show that the distributions of mechanical properties strongly depend on the variation of microstructure. It is found that hardness increases and ductility decreases with the increase of ZrO₂, which is attributed to the variation of the matrix phase from the metal to the ceramic. Bending strength and elastic modulus decrease as the volume fraction of ZrO₂ increase from 0% to 40%, however, increase as the volume fraction of ZrO₂ increase from 50% to 100%. These are mainly caused by the weakly bonded ceramic/metal interface. Crown