MATRIX CRACKING IN INTERMETALLIC COMPOSITES CAUSED BY THERMAL-EXPANSION MISMATCH

Matrix cracking in brittle matrix composites caused by thermal expansion misfit has been addressed by a combination of experiment with calculations. It has been established that a critical reinforcement size exists below which matrix cracking is suppressed. This concept is summarized in terms of a non-dimensional group R, of the reinforcement size, misfit strain, elastic modulus and matrix toughness. It has also been demonstrated that the interface exerts a major influence on matrix cracking, through relaxation of constraint by debonding. Furthermore, the results imply that a failsafe value of R exists, of order unity, that can be used to select material combinations that suppress matrix cracking.