R-curve behaviour of 2Y-TZP with submicron grain size

Nanocrystalline powders were used to prepare fracture test specimens of 2Y-TZP with average grain sizes between 150 and 900 nm. Crack extension and attendant R-curve behaviour were studied in both air and vacuum. The plateau values in air and vacuum increase linearly with grain size from 3.1 to 5.1 MPa m1/2 and from 4.7 to 6.7 MPa m1/2, respectively. The size of the process zone was quantified using Raman microscopy and the results correlated to both the plateau values and the shape of the R-curve as a function of grain size.