Mechanical Behavior of Alumina–Silicon Carbide „Nanocomposites”

The fracture behavior of Al 2 O 3 containing 5 vol% 0.15μm SiC particles was investigated using indentation techniques. A significant increase in strength was achieved by the addition of SiC particles to the base Al 2 O 3 . Specifically, the strength increased from 560 MPa for Al 2 O 3 to 760 MPa for the composite samples (average values for unindented hotpressed bars tested in four‐point bending). After annealing for 2 h at 1300°C, the average strength of the composite samples increased to about 1000 MPa. Toughness was estimated using indentation‐strength data. While there was a slight increase in toughness, the increase was not sufficient to account for the increase in the unindented strength on SiC particle addition. It is suggested that the observed strengthening and apparent toughening were due to a machining‐induced compressive surface stress.