MECHANICAL-PROPERTIES OF A 20 VOL-PERCENT SIC WHISKER-REINFORCED, YTTRIA-STABILIZED, TETRAGONAL ZIRCONIA COMPOSITE AT ELEVATED-TEMPERATURES

The high-temperature deformation behavior of a SiC whisker-reinforced, yttria-stabilized, tetragonal zirconia polycrystalline composite cont aining 20 vol % SiC whiskers (SiC/Y-TZP) has been investigated. Tensil e tests were performed in vacuum at temperatures from 1450-degrees-C t o 1650-degrees-C and at strain rates from 10(-3) to 10(-5) s-1. The ma terial exhibits useful high-temperature engineering properties (e.g., approximately 100 MPa and 16% elongation at T = 1550-degrees-C and at a strain rate of approximately 10(-4) s-1). The stress exponent was de termined to be n almost-equal-to 2. Scanning electron microscopy was u sed to characterize the grain size and morphology of the composites, b oth before and after deformation. The grain size in the composite was initially fine, but coarsened at the test temperatures; both dynamic a nd static grain growth were observed. The morphology of ceramic reinfo rcements appears to affect strongly the plastic deformation properties of Y-TZP. A comparison is made between the properties of monolithic Y -TZP, 20 wt. % Al2O3 particulate-reinforced Y-TZP (Al2O3/Y-TZP), and S iC/Y-TZP composites.