Indentation

About: Indentation is a research topic. Over the lifetime, 13002 publications have been published within this topic receiving 340476 citations.

Hardness and elastic modulus of TiN based on continuous indentation technique and new correlation

Abstract: Young’s modulus and hardness of TiN films are reported. The films, deposited on 440C stainless steel, range between 0.25 and 1.0 μm in thickness. They fall to within 3% of stoichiometry and have a 〈111〉 texture. Within experimental resolution, the properties of films with different thickness are indistinguishable: calculated values of Young’s modulus and hardness are 550±50 GPa and 31±4 GPa, respectively. Properties are obtained from a continuous indentation technique. A new correlation is used for identifying whether all films have the same properties, independent of thickness, and for measuring hardness of thin films. The same correlation is utilized for measuring machine compliance and obtaining the profile of the indenter tip. An elasticity analysis aids in obtaining elastic modulus from compliance data.

On the determination of spherical nanoindentation stress-strain curves

Abstract: Instrumented nanoindentation experiments, especially with sharp tips, are a well-established technique to measure the hardness and moduli values of a wide range of materials. However, and despite the fact that they can accurately delineate the onset of the elasto-plastic transition of solids, spherical nanoindentation experiments are less common. In this article we propose a technique in which we combine (i) the results of continuous stiffness measurements with spherical indenters–with radii of 1 μm and/or 13.5 μm, (ii) Hertzian theory, and (iii) Berkovich nanoindentations, to convert load/depth of indentation curves to their corresponding indentation stress–strain curves. We applied the technique to fused silica, aluminum, iron and single crystals of sapphire and ZnO. In all cases, the resulting indentation stress–strain curves obtained clearly showed the details of the elastic-to-plastic transition (i.e., the onset of yield, and, as important, the steady state hardness values that were comparable with the Vickers microhardness values obtained on the same surfaces). Furthermore, when both the 1 μm and 13.5 μm indenters were used on the same material, for the most part, the indentation stress–strain curves traced one trajectory. The method is versatile and can be used over a large range of moduli and hardness values.

On the Measurements of Rigidity Modulus of Soft Materials in Nanoindentation Experiments at Small Depth

Abstract: It is of interest to measure the modulus of rigidity at small indentation depths for many systems, such as thin films, nanocomposites, biomaterials, etc. Depth-dependence of the rigidity modulus of...

Effects of 'sinking in' and 'piling up' on estimating the contact area under load in indentation

Abstract: The phenomena of the 'piling up' and 'sinking-in' of surface profiles in conical indentation in elastic-plastic solids with work hardening are studied using dimensional and finite-element analysis The degree of sinking in and piling up is shown to depend on the ratio of the initial yield strength Y to Young's modulus E and on the work-hardening exponent n The widely used procedure proposed by Oliver and Pharr for estimating contact depth is then evaluated systematically By comparing the contact depth obtained directly from finite-element calculations with that obtained from the initial unloading slope using the Oliver-Pharr procedure, the applicability of the procedure is discussed

Influence of crystal anisotropy on elastic deformation and onset of plasticity in nanoindentation -- a simulational study

Abstract: Using molecular-dynamics simulation we simulate nanoindentation into the three principal surfaces—the (100), (110), and (111) surface—of Cu and Al In the elastic regime, the simulation data agree fairly well with the linear elastic theory of indentation into an elastically anisotropic substrate With increasing indentation depth, the effect of pressure hardening becomes visible When the critical stress for dislocation nucleation is reached, even the elastically isotropic Al shows a strong dependence of the force-displacement curves on the surface orientation After the load drop, when plasticity has set in, the influence of the surface orientation is lost, and the contact pressure (hardness) becomes independent of the surface orientation