Fracture toughness of nanocrystalline ZrO2-3mol% Y2O3 determined by Vickers inde

2019-10-10 10:19:51

fracture grain ZrO2 toughness nanocrystalline

责任者: Cottom, B.A.;Mayo, M.J. 单位: Dept. of Mater. Sci. & Eng., Pennsylvania State Univ., University Park, PA, USA 来源出处: Scripta Materialia(Scr. Mater. (USA)),1996/03/01,34(5):809-14 摘要: Nanocrystalline 3Y-ZrO2 with densities ranging from 90.4% to 98.7% of theoretical and grain sizes from 55 nm to 160 nm were tested by Vickers indentation. The hardness of nanocrystalline and submicron (Tosoh) 3Y-ZrO2 was a strong function of density but independent of grain size and could be expressed as hardness (GPa)=0.549*density (in%)+40.449 with a correlation coefficient, R, of 0.919. The fracture toughness of both submicron and nanocrystalline 3Y-ZrO2 was low, about 2.5-4.5 MPa·m½, in contrast with the 8.4 MPa·m½ for a micron-grained 3Y-ZrO2 sample. In addition, the fracture toughness was relatively constant over all density and grain size ranges studied (55-400 nm; 90-100% density). The low fracture toughness, combined with no perceptible grain size dependence, implies that there is not a significant room temperature ductility mechanism peculiar to nanocrystalline materials. Minor effects may exist, but they are not sufficient to noticeably increase the fracture toughness. Because the data fit with existing trends of decreasing transformation toughening with decreasing grain size, it is presumed the poor fracture toughness of the nanocrystalline samples is due to a diminished capacity to transformation toughen via the tetragonal-to-monoclinic transformation 关键词: ceramics;density;fracture toughness;grain size;hardness;martensitic transformations;nanostructured materials;transformation toughening;zirconium compounds;nanocrystalline ZrO2-Y2O3;Vickers indentation;hardness;fracture toughness;density;grain size ranges;transformation toughening;tetragonal-to-monoclinic transformation;ZrO2;ZrO2-Y2O3