Investigation of the Bulge Test Response of Molybdenum Thin Films at Room Temperature and at 100 °C

Abstract

It is well known that mechanical properties of materials are dependent on the volume of material that is deformed. This size effect has been investigated for metal nanostructures and thin films. However, to date there are no known studies of how confined geometries affect properties of BCC metals. The current investigation began with the aim of shedding new light on this open question. Because it allows for isothermal tensile tests of thin films in a temperature regime from cryogenic to elevated temperatures, the approach taken is that of bulge testing. Molybdenum was chosen as a starting material because of its insensitivity to oxidation at temperatures below 300°C. After describing the coating procedure and the parameters associated with the coating process, the coating microstructure is presented. Qualitative results for investigation of the oxidation of Mo thin films are also presented. We then describe the method to obtain free-standing thin films. Finally, the apparatus for performing bulge tests and several stress-strain curves is presented. Due to limitations with the measurement equipment, for the current round of experiments, it was not possible to test the Molybdenum films at temperatures high enough to induce a brittle-to-ductile transition.

Elastic anisotropy of polycrystalline Au films: Modeling and respective contributions of X-ray diffraction, nanoindentation and Brillouin light scattering

“…Knowing r 11 and r 22 , it is possible to determine 1 2 S hkl 2 and S hkl 1 from the slope and the intercept of the linear fit of e hkl U;W as a function of sin 2 W, as shown in Eq. (10). Therefore the hkl-dependent elastic constants can be plotted as a function of orientation parameter C(h k l), which is defined by…”

“…Therefore, many techniques have been developed to evaluate its value for small structures, including nanoindentation [7], microbeam bending [8], bulge test [9,10], microtensile [11,12], acoustic microscopy [13,14], picosecond ultrasonics [15,16], Brillouin light scattering (BLS) [17], and in situ tensile testing under X-ray diffraction (XRD) [18] while combined global approaches have been proposed [19]. However, principles and physical background are inherent to each technique.…”