Instrumented nanoindentation

The indentation hardness signifies the mean pressure that can be sustained under the indentation load and is defined as 

The indentation hardness is commonly used as a convenient material parameter with which different materials can be ranked in terms of their strength values. 

The use of depth-sensing instrumented indentation to study the inelastic deformation response of thin metal films on substrates remains a work in progress. A key underlying challenge here is to estimate the connection between the projected contact area Ac and the indenter depth of penetration h for particular geometrical configurations, constraint conditions and material parameters by properly accounting for the manner in which the material flows around the indenter. References to relevant literature on this topic can be found in Section 6.8.2 as well as in reports by Ohver and Pharr (1992), Nix (1997) and Dao et al. (2001). 

A bilayer is made by diffusion-bonding a metallic layer of thickness hf to 

15x10 (°C) , and Mf/oYf = 3800, where the symbols denote the various material parameters defined earlier in this chapter. The corresponding properties of the ceramic layer are Eg = 380 GPa, Vg = 0.25, and ag = 5x10 (°C) h The metallic layer can be assumed to be an elastic-ideally plastic material with equal values of tensile and compressive yield strengths. For the purposes of this exercise problem, the properties of both layers can be assumed to be independent of temperature, hf/hg = 1. 

---

Fig. 7.35. Schematic illustrations of two different designs for an instrumented nanoindenter. Figure (a) is adapted from Materials Test Systems Corporation, Eden Prairie, Minnesota, and (b) from Hysitron Corporation, Minneapolis, Minnesota.

Appendix H Instrumented Nanoindentation Applied to Thin Films... 

It should be noted that hardness values obtained from instrumented nanoindentation and microindentation may differ significantly and this phenomenon is invoked as the indentation size effect (ISE). 

Another advantage of instrumented nanoindentation is that the elastic properties of materials can be determined. The composite modulus (specimen-tip) E is extracted from... 

Using low load and increasing progressively the load, the instrumented nanoindentation technique allows for investigation of the elastic-plastic response of coatings as well as their adhesion to the substrate (Figure H.8). Indeed, the probe size can be adjusted to the film thickness using appropriate loads. For dedicated... 

In AFM, the relative approach of sample and tip is nonnally stopped after contact is reached. Flowever, the instrument may also be used as a nanoindenter, measuring the penetration deptli of the tip as it is pressed into the surface of the material under test. Infomiation such as the elastic modulus at a given point on the surface may be obtained in tliis way [114], altliough producing enough points to synthesize an elastic modulus image is very time consuming. 

In this chapter, we overview basic techniques for making nanoscale adhesion and mechanical property measurements. Both quasi-static and dynamic measurements are addressed. In Section 2 of this chapter, we overview basic AFM instrumentation and techniques, while depth-sensing nanoindentation is overviewed in Section 3. Section 4 addresses recent advances in instrumentation and techniques... 

Nanoindentations were carried out by using a commercial AFM (AutoProbe CP Research, Park Scientific Instruments) equipped with a commercial capacitance transducer (TriboScope, Hysitron) with a three-sided pyramidal dia-... 

Nanoindentation instruments emerged as a consequence of the need to characterize mechanically the surfaces of thin films and near surfaces (within 1000 nm of the surface). The type of instrumentation and data processing needed for nanoindentation is essentially different from the microhardness tester (Pollock, 1992). 

Table 2.2. Commercial nanoindentation instrument specifications. (From Pollock, 1992.)...

Another modem instrument used for nanoindentation and for nanotribological studies of polymers is the surface force microscope (SFM) (Ovemey, 1995a). 

The development of multipurpose nanoindentation instruments that also perform scratch testing, profiling, and measurements of scratch hardness, film stress, friction, and other surface-mechanical properties. 

In situ TEM can be performed to study the optical, electrical, and mechanical properties of materials. The instrumentation involved considers several types of specimen holders. At present, the main types of specimen probes used in industry are electrical probing (TEM-STM) [32], micro-force (TEM-nanoindenter) [33], nano-force (TEM-AEM) [34, 35], optical, scanning fiber, multiple electrical wire. 

---