Sudden excursions of unusually large magnitude 1 m , “giant pop-ins,” have been observed in the force-displacement curve for high load indentation of crystalline germanium Ge . A range of techniques including Raman microspectroscopy, focused ion-beam cross sectioning, and transmission electron microscopy, are applied to study this phenomenon. Amorphous material is observed in residual indents f...

Nanoindentation morphologies of crystalline copper have been probed at the grain scale. Experimental tests have been conducted on nanocrystalline (NC), ultrafine-grained (UFG), and coarse-grained (CG) copper samples with a new Berkvoich indenter at the strain rate of 0.04/s without holding time at an indentation depth of 2000 nm at room temperature. As the grain size increases, the height of th...

The accuracy of mechanical properties from depth-sensing indentation, or nanoindentation, depends on the accuracy of the displacement measurement used to calculate these properties. Here, current nanoindentation techniques and analysis methods for accurate displacement measurements are reviewed. First, the ability of a commercial instrument to sense the surface of soft materials is examined. Se...

Thin films have an important part to play in modern technology. It is difficult to characterize the mechanical properties of thin films because the films cannot usually be investigated separately from the substrate. One of the few methods that can be used for such investigations consists in making an indentation in the film by applying an extremely small and accurately controlled force while at...

Structural, optical and nanomechanical properties of nanocrystalline Zinc Telluride (ZnTe) films of thickness upto 10 microns deposited at room temperature on borosilicate glass substrates are reported. X-ray diffraction patterns reveal that the films were preferentially oriented along the (1 1 1) direction. The maximum refractive index of the films was 2.74 at a wavelength of 2000 nm. The opti...

We have developed a tool for performing surgical operations on living cells at nanoscale resolution using atomic force microscopy (AFM) and a modified AFM tip. The AFM tips are sharpened to ultrathin needles of 200-300 nm in diameter using focused ion beam etching. Force-distance curves obtained by AFM using the needles indicated that the needles penetrated the cell membrane following indentati...

We consider the effect of an elastic modulus that decreases with depth on the load-displacement relation for indentation of a graded half space by a rigid indenter. A closed-form approximation incorporating features of the plate on an elastic substrate and the Hertzian contact theory is compared with finite element results for the case of a uniform stiff layer on a homogeneous substrate. Some g...

Experimental assessment of the reverse algorithms that enable the extraction of plastic properties from the load–depth of penetration curves was conducted. Results show that they predict the stresses at 3.3% and 5.7% representative strains for Berkovich and 60 cone-equivalent three-sided pyramidal indenters, respectively, with good accuracy. It was shown that the uniaxial stress–strain curves c...

A new procedure for identifying the mechanical behavior of individual phases within a bi-material (matrix-particles) is presented. The case AlSi10Mg (large globularized Si-rich particles surrounded by an α-Al phase) processed additive manufacturing and post-treated taken as typical example. Grids nano-indentation tests are performed at different locations on nanocomposite using Berkovich indent...

A solution is given for the frictionless indentation of an elastic half-space by a flat-ended cylindrical punch with a central circular recess, when the load is large enough to establish a circular region of contact in the recess. The problem is reduced to two simultaneous Fredholm equations using the method of complex potentials due to Green and Collins. Results are presented for the relations...