Acoustic Emissions from Microindentation Fracture Toughness Tests

There is interest in the materials research community in the development of materials for high performance, high temperature turbine engine design. As they are in the development stage, these materials are in very short supply, and it is, therefore, difficult to determine the most basic of material parameters. The alloys and ceramics under consideration are typically very brittle, and one of the critical material parameters needed to evaluate them is fracture toughness. Fracture toughness is the measure of notch sensitivity of a material and knowledge of this parameter allows decisions to be made about the inspectability and inspection requirements for the materials by establishing a critical crack length. Processing techniques and toughening mechanisms being investigated during material development can also be evaluated by making precise measurements of toughness changes