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.