Mapping strain fields induced in Zr-based bulk metallic glasses during in-situ nanoindentation by X-ray nanodiffraction

Abstract

A pioneer in-situ synchrotron X-ray nanodiffraction approach for characterization and visualization of strain fields induced by nanoindentation in amorphous materials is introduced. In-situ nanoindentation experiments were performed in transmission mode using a monochromatic and highly focused sub-micron X-ray beam on 40 lm thick Zr-based bulk metallic glass under two loading conditions. Spatially resolved X-ray diffraction scans in the deformed volume of Zr-based bulk metallic glass covering an area of 40 Â 40 lm 2 beneath the pyramidal indenter revealed twodimensional map of elastic strains. The largest value of compressive elastic strain calculated from diffraction data at 1 N load was À0.65%. The region of high elastic compressive strains (<À0.3%) is located beneath the indenter tip and has radius of 7 lm. V

Structural periodicity in laser additive manufactured Zr-based bulk metallic glass

“…This technique is well established for investigating structural evolution [18][19][20] and strains in BMGs. [21][22][23][24][25] For the synchrotron measurements, thin strips ($1.5 Â 18 Â 0.15 mm 3 ) were cut from both the "center" and "edge" of the AMZ4 block with a low speed diamond saw (Buehler IsoMet) and the surface was ground with 4000 grit SiC paper to remove surface asperities. Samples were cleaned with acetone and ethanol and then adhered to an Al window (vacuum-grade Al, wire electrical discharge machined) for the X-ray measurements.…”

Shear Banding in a Contact Problem between Metallic Glasses

“…Consequently, the deformation, while irregular, concentrates below the surface, at the maximum deviatoric strain due to the Hertz contact. Such a kind of deformation without shear bands was already observed experimentally with in situ X-ray diffraction in Zr-based metallic glass samples [59]. However, the disorder was unfortunately not characterized in these samples.…”

Progress of in situ synchrotron X-ray diffraction studies on the mechanical behavior of materials at small scales

“…As illustrated in Fig. 41, this instrument is coupled with X-ray diffraction in transmission geometry using hard X-ray beams that are focused down to a size of the order of 200 nm [204,205]. The local mechanical deformation, the microstructural changes, and stress distributions can be studied during step-wise indentation of lamellas of several micrometer thick films as well as bulk metallic glasses.…”

“…X-ray nanodiffraction on a lamella of an indented CrN-Cr multilayer thin film in a transmission geometry providing access to the local stress fields around the indenter imprint was demonstrated by Stefenelli et al [222]. This diffraction technique was later on coupled with the in situ indenter at the P03 beamline at PETRA III for monitoring the strain field and the microstructural changes in Zrbased bulk metallic glasses [204] and in several micrometer thick TiN films (Fig. 48) [205] during the indentation process.…”