Influence of Vickers Indenter Tip Geometry on the Macro-indentation Properties of γ-TiAl Alloys
Abstract
The instrumented indentation testing of γ-TiAl imposes the use of large loads only possible with diamond pyramidal indenters. The geometry of such indenters (e.g. Vickers indenter) has to be precisely defined. In addition, the so-called zeropoint of the loading curve (i.e. the first point of the indenter coming into contact with the sample) has to be precisely located to ensure accurate measurements. Computer models may help to appropriately post-process the raw data by taking into account several crucial factors, among these, the initial stage of the loading curve, the influence of the actual indenter tip geometry, friction effects and pile-up or sink-in phenomena if any. In this work the influence of the geometry of the indenter tip on relevant indentation properties is investigated during experimental and numerical macro-instrumented indentation in the case of a hip-homogenized γ-TiAl alloy. The employed macro-instrumented indentation is characterized by loading forces ranging from 2 to 200 N. The developed 3D structural contact model is implemented in the Comsol Multiphysics 3.5a environment and involves large displacements, strong singularity and materials non linearity.