Microstructure and properties of the Al2O3-Ti3AlNb composites.

The study was concerned with the Al2O3-Ti3AlNb composites produced by powder metallurgy. The microstructures of the sintered composites were described qualitatively and quantitatively. The physical and mechanical properties of the samples examined during the experiments included: porosity, hardness, elastic modulus and brittle toughness. It has been shown that the properties of the composites depend not only on their constituents but also on the particular features of their microstructural structure, which in turn depend on the technology employed. The properties of the composites appeared to be intermediate between those of ceramics and those of alloys with intermetallic matrix. They depend, in a non-linear way, on the volumetric shares of the ceramics and the specific surface area of the phase boundaries. The deviations from the linear theory of mixing can be explained in terms of the disintegrated intermetallic precipitates and pores. It has also been found that with increasing volumetric share of the ceramic material, the sizes of the pores and of the intermetallic particles decrease, whereas their shapes remain almost unchanged.