THE MECHANICAL PERFORMANCE OF ALUMINA AS A FUNCTION OF GRAIN-SIZE

The mechanical properties of ceramics usually exhibit a strong depende nce on the microstructure. In the present study, the dependence of mec hanical properties (namely, flexure strength, fracture toughness, Weib ull modulus and R-curve behavior) of alumina on grain size is investig ated. The results suggest that the strength of alumina decreases with increasing grain size. However, owing to the fact that specimens with a certain grain size do not behave as brittle, Griffith solids, the st rength is not exactly proportional to G-0.5. The fracture toughness in creases with increasing grain size; the toughness was determined by th e single-edge precracked beam (SEPB) and the indentation techniques. N o dependence of Weibull modulus or R-curve behavior on grain size was observed. However, the Weibull modulus and R-curve behavior are strong ly correlated with each other. R-curve behavior was observed for the s pecimens with higher Weibull modulus.