Toughening alumina with silver and zirconia inclusions

Both silver and zirconia inclusions are added into an alumina matrix, the strength and toughness of the composites are determined. The toughening agents prohibit the grain growth of the matrix, the strength of alumina is, therefore, enhanced. The addition of two toughening agents also enhances the toughness of alumina. The presence of Ag inclusions raises the transformation ability of ZrO2; however, the toughness increase of the Al2O3–ZrO2–Ag composites is slightly lower than the sum of the toughness increase of Al2O3–ZrO2 and of Al2O3–Ag composites. The present study demonstrates that the toughening effects contributed by a transformation toughening agent and a ductile toughening agent can interact with each other; nevertheless, such interaction depends strongly on the microstructure of the composites.