Anomalous high activation energy for creep in nanostructured 3YTZP/Ni cermets

摘要

The plastic behavior of cermets based on a 3 mol percent yttria-stabilized tetragonal zirconia matrix that incorporates nanometric nickel inclusions (3YTZP-Ni), with 2.5, 5 and 10 vol. percent of nickel content, has been studied by constant load tests in compression carried out in argon atmosphere. The microstructure of these composites consists of nanometric nickel inclusions homogeneously dispersed into a fine-grained zirconia matrix (about 200 nm). The microstructural and mechanical results obtained show that the creep behavior is controlled by the zirconia matrix as in 3YTZP-based cermets with micrometric Ni inclusions (3YTZP/(mu -Ni); whereas the stress exponent values are similar to those of high-purity monolithic 3YTZPs, anomalous high values of the activation energy have been measured. The ceramic/metal interface plays a crucial role for creep properties; the strong TZP-Ni interface matching can be at the origin of these high values of the activation energies for creep.