Thermodynamics and microstructure of Ti-ZrO2 metal-ceramic functionally graded materials

The standard Gibbs free energy functions of Ti2O and Ti5O9 have been predic ted according to the quasi-parabola rule. To determine the synthesis condit ions of Ti-ZrO2 composite, the thermodynamic stability of various oxides in Ti-Zr-O system and the co-existing region of Ti and ZrO2 have been obtaine d by thermodynamic calculation. According to the thermodynamic analysis, it can be deduced that Ti could probably react with ZrO2 in the synthesis pro cesses of Ti-ZrO2 functionally graded materials (FGMs). But the experimenta l results show that there is no reaction product in the Ti/ZrO2 interfaces and the bending state between Ti and ZrO2 is physical in the composite. ZrO 2 (3 mol.% Y2O3-stabilized zirconia) mainly exists as tetragonal phase in t he prepared Ti-ZrO2 FGMs. The presence of Ti exerts an important influence on the transformation of ZrO2 from tetragonal to monoclinic phase. Ti-ZrO2 system functionally graded materials (FGMs) have been prepared by powder me tallurgical method. The microstructural features of Ti-ZrO2 system FGMs hav e been appropriately interpreted by the heat percolation model. (C) 2000 El sevier Science S.A. All rights reserved.