Mechanical Properties of Compositionally Modulated Au-Ni thin films using Indentation and Microbeam Deflection Techniques

Abstract

The “supermodulus effect” has been reported as an anomalous increase of as much as several hundred percent in the elastic moduli of compositionally-modulated thin metal films in a narrow range of modulation wavelength. The direct measurement of this effect has, however, been limited due to the very small dimensions of the test material. The mechanical properties of compositionally-modulated Au-Ni thin films (one of the first systems in which the supermodulus effect was reported) were studied on their substrates by indentation and microbeam-deflection techniques using a Nanoindenter. The films were fabricated by alternately sputtering Au and Ni onto [100] Si substrates for the indentation tests and onto prefabricated SiO2 cantilever beams with an initial Cr layer (for adhesion) for the beam deflection tests. All of the films have strong [111] textures and exhibit the structural characteristics of the films for which the modulus enhancement was reported. In particular, an increase in the average lattice parameter normal to the plane of the film over a narrow range of modulation wavelengths near 2 nm was noted. The modulation wavelengths range from 0.8 to 4.5 nm. The results from both indentation and microbeam deflection tests reveal no unusual plastic or elastic properties in these samples.

Metallic multilayers at the nanoscale

“…Corrections to fit a series of modulus measurements to adjusted beam lengths resulted in increasing the measured film modulus by more than 100% -which is as large or larger than the magnitude of enhancement found for any recent Young's modulus investigation(43.46). Hardness measurements reported for indentation depths greater than 10% of the film thickness (60) were not representative of the A m i multilayer as later proven in a Meyer-plot analysis of applied load vs indentation depth (61). In all, the micmindentatioddeflection studies have potential but proved wanton in this case for evaluating the elastic moduli of anisotropic behavior in Au/Ni metallic multilayers.…”

In situ thermo-mechanical bending behavior of VO2 microcantilevers across the phase transition

“…In currently proposed model, nanoscale probe perpendicularly bends the beam avoiding the occurrence of slip-friction between AFM tip and sample surface, sometimes observed in AFM based tests. Previously, Baker et al employed a nanoindenter to deflect a bilayer beam and calculated the stiffness from load deflection data showing linear elastic behavior [24]. Mechanical deformation behavior of metallic single crystal microcantilevers have been explored to calculate geometrically necessary dislocations (GNDs) using nanoindentation bending studies [25,26].…”

Experimental Techniques for the Measurement of Mechanical Properties of Materials Used in Microelectromechanical Systems

“…Microbeam deflection experiments using a nanoindenter are well established for determining yield stress and elastic stiffness of materials used in MEMS at the same length scale [47][48][49][50] . In this technique, very small cantilever beam specimens (Fig.…”

“…15. The elastic modulus and the yield strength of the material can be determined from the load deflection curve using beam theory or FEM [47][48][49][50] . This technique can also be extended for measuring the fatigue response of the films by superimposing an oscillating signal along with the monotonic force signal and using the continuous stiffness monitoring option of the nanoindenter system 51 .…”