Effect of Grain Size on Transverse Bend Strength of Alumina and Magnesia

Experimental findings are presented for the effect of microstructure on the room‐temperature transverse bend strength properties of hot‐pressed dense pure alumina and magnesia. Bend strength shows an exponential dependence on porosity but is sensitive to fabricating temperatures because of changes in grain size. Log‐log plots of strength (extrapolated to zero porosity) versus grain size reveal the relation S= 86,000G−1/3 (psi) for alumina and S= 50,000G−1/6 (psi) for heat‐treated specimens of magnesia (G= grain size in microns).