Following peak profiles during elastic and plastic deformation: A synchrotron-based technique

Abstract

Understanding the elastic and plastic deformation properties of nanostructured metals requires the development of in situ testing methods that can follow the footprints of the deformation mechanism͑s͒ during mechanical testing. Here we present an in situ synchrotron x-ray-diffraction technique which allows the measurement of diffraction profiles continuously during mechanical testing, providing an in situ peak profile analysis capability. The in situ approach is achieved thanks to the development of a microstrip detector allowing the instantaneous measurement of the diffraction pattern over a 2 range of 60°. This in situ technique allows for the first time a comparison of the footprints of the plastic deformation mechanism during loading and after unloading. The measurements are performed on several types of freestanding dog bones, covering sample thicknesses down to the submicron range.

Microstructure and deformation mechanisms in nanocrystalline Ni–Fe. Part I. Microstructure

“…Details on the beamline and measurement set-up can be found in Refs. [33,34]. Two methods were used to analyse the diffraction patterns: single line analysis (SLA) and whole powder pattern modelling (WPPM).…”

From Micro‐ to Macroplasticity

“…Transmission electron microscopy analysis showed large grains (200-400 nm) with a visible subgrain boundary structure resulting in a maximum coherent XRD domain size in the order of 80 nm. Mini-dogbones, prepared as described previously [27], were used for mechanical testing.…”

“…The in situ technique allows for a diffraction pattern to be taken continuously during deformation over a 2 h range of 60°. For more details on the technique and the fitting procedure of the XRD spectra we refer to previous publications [23,27,30]. Figure 3.…”

“…For HPT-Ni, the FWHM behavior also indicated two distinct hardening regimes, the first characterized by a constant FWHM upon unloading, and the second by an increase relative to the as-prepared state, as expected from dislocation plasticity. [27] Similar to ED-Ni, the second regime demonstrated time dependence, albeit one less pronounced.…”

A Miniaturized Biaxial Deformation Rig for in Situ Mechanical Testing

“…The diffraction peaks were fitted by asymmetric PVII functions. More details on the beam line and fitting procedures can be found in references [56,57]. Elastic lattice strains ε hkl were calculated from the evolution of the diffraction peak positions θ hkl : Figure 13 displays the evolution of the lattice strain derived from the {311} diffraction peak as a function of applied stress for the three experiments.…”