An indentation method for determining the film thickness, Young’s modulus, and hardness of bilayer materials

Abstract

Simultaneously determining the film thickness, Young’s modulus and hardness of film and substrate is a significant challenge due to the substrate effect. A method to solve the inverse problem of characterizing the mechanical properties of bilayer materials for instrumented indentation testing is proposed. This is done in combination with a weight function which could be obtained via finite element simulation. Using the proposed method, the film thickness and Young’s modulus of film-substrate materials, and the hardness values of the film and substrate could be determined. The proposed method is applicable to Vickers, Berkovich, and 70.3° conical indenters. Within the study range, numerical and theoretical results show that this method is both feasible and accurate in determining the above parameters, compared with existing experimental results. The method flow chart to determine the above parameters is also shown. This method separates the coupling effect between the film and the substrate in the bilayer material, giving it practical prospects in the field of indentation testing technology.

3D finite element simulation of scratch testing to quantify experimental failure mechanisms of a thin film

“…According to the literature, the mechanical properties of a film could be determined through indentation tests at different penetration depths up to a certain percentage of the film thickness, where the influence of the substrate can be excluded from the measurement data once the values of Young's modulus and hardness are stabilized [47].…”

Surface effects on the spherical indentation of biological film/substrate structures

“…Based on the discontinuous elastic interface transfer model, a new model was developed with two weighting factors [19]. Zhao et al [20] proposed a weight function to extract the film thickness, Young's modulus and hardness of materials from Vickers, Berkovich and conical indentations. The dimensional analysis method was also adopted to identify the elasticity of thin-film materials.…”