Abstract
Most intelligent materials are brittle. From the engineering point of view, it is just important to evaluate the fracture toughness. KIC is a standerd value to evaluate the brittleness. However, it is difficult to prepare (form) test specimens. Vickers hardness tester is a good tool to know many mechanical propaties without fracture. In this paper, we introduce evaluate methods of fracture toughness for brittle materials by means of Vickers hardness tester. Indentation fracture (IF) method is easy to detarmine KIC to measure crack length around the indentation, load, diagonal and Young's modules. On the other hands, we have suggested a new method to evaluate brittleness by means of critical deformation energey (Ef). Ef is calcurated by critical load (Pf) and critical diagonal (df) only. This method is useful to evaluate brittleness of small or thin specimens.
