Role of microstructure in hertzian contact damage in silicon nitride: I, mechanical chatacterization

摘要

In this Part I of a two-part study of hertzian induntation in silicon nitride we characterize irreversible contact damage as a function of microstructure. Three controlled silicon nitride microstructures are examined, representing a pro- gression toward greater long-crack toughness: fine (F), bi- modal with predominantly equiaxed α grains; medium (M), bimodal with mostly β grains of intermediate size; and coarse (c), with almost exclusively elongated β grains.