In situ micropillar deformation of hydrides in Zircaloy-4

Deformation of hydrided Zircaloy-4 has been examined using in situ loading of hydrided micropillars in the scanning electron microscope and using synchrotron X-ray Laue microbeam diffraction. Results suggest that both the matrix and hydride can co-deform, with storage of deformation defects observed within the hydrides, which were twinned. Hydrides placed at the plane of maximum shear stress showed deformation within the hydride packet, whilst packets in other pillars arrested the propagation of shear bands. X-ray Laue peak broadening, prior to deformation, was associated with the precipitation of hydrides, and during deformation plastic rotation and broadening of both the matrix and hydride peaks were observed. Post-mortem TEM of the deformed pillars has indicated a greater density of dislocations associated with the precipitated hydride packets, while the observed broadening of the hydride electron diffraction spots further suggests that plastic strain gradients were induced in the hydrides by compression

Synchrotron x-ray scattering analysis of nylon-12 crystallisation variation depending on 3D printing conditions

7Nylon-12 is an important structural polymer in wide use in the form of fibres and bulk structures. Fused filament fabrication (FFF) is an extrusion-based additive manufacturing (AM) method for rapid prototyping and final product manufacturing of thermoplastic polymer objects. The resultant microstructure of FFF-produced samples is strongly affected by the cooling rates and thermal gradients experienced across the part. The crystallisation behaviour during cooling and solidification influences the micro- and nano-structure, and deserves detailed investigation. A commercial Nylon-12 filament and FFF-produced Nylon-12 parts were studied by differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) to examine the effect of cooling rates under non-isothermal crystallisation conditions on the microstructure and properties. Slower cooling rates caused more perfect crystallite formation, as well as alteration to the thermal properties.openopende Jager B.; Moxham T.; Besnard C.; Salvati E.; Chen J.; Dolbnya I.P.; Korsunsky A.M.de Jager, B.; Moxham, T.; Besnard, C.; Salvati, E.; Chen, J.; Dolbnya, I. P.; Korsunsky, A. M

Nano-scale mapping of lattice strain and orientation inside carbon core SIC fibres by synchrotron X-ray diffraction

The strongest fibres available today are carbon-based, made from carbon nanotubes (CNTs) or reduced graphene oxide flakes (RGOFs). Carbon fibres (CFs) were first developed half a century ago. Control of the thermal, chemical and mechanical processing allows obtaining desired combination of structure, strength and stiffness. In practical use, CFs are typically incorporated into larger scale systems that require multi-scale characterisation. In the present study we considered an aerospace composite consisting of titanium alloy matrix reinforced with unidirectional silicon carbide fibres with carbon monofilament core. By combining synchrotron-based imaging and nano-focused X-ray beam scattering with Focused Ion Beam stress evaluation, we construct detailed maps of structure and strain inside this material. Eigenstrain modelling was used to reconstruct the full residual strain state within the fibre cross-section. The joined-up experimental and theoretical approach allows extracting information about fibre structure down to the nanoscale, developing insight into its processing history, and revealing the existence of significant residual strains that have a strong effect on the performance of CFs in service. © 2014 Elsevier Ltd

Multiscale synchrotron scattering studies of the temperature-dependent changes in the structure and deformation response of a thermoplastic polyurethane elastomer

The distinct molecular architecture and thermomechanical properties of polyurethane block copolymers make them suitable for applications ranging from textile fibers to temperature sensors. In the present study, differential scanning calorimetry (DSC) analysis and macroscopic stress relaxation measurements are used to identify the key internal processes occurring in the temperature ranges between −10 °C and 0 °C and between 60 °C and 70 °C. The underlying physical phenomena are elucidated by the small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) study of synchrotron beams, allowing the exploration of the structure-property relationships as a function of temperature. In situ multiscale deformation analysis under uniaxial cyclic thermomechanical loading reveals a significant anomaly in the strain evolution at the nanoscale (assessed via SAXS) in the range between −10 °C and 0 °C owing to the ‘melting’ of the soft matrix. Furthermore, WAXS measurement of crystal strain within the hard regions reveals significant compressive residual strains arising from unloading at ∼60 °C, which are associated with the dynamic shape memory effect in polyurethane at these temperatures

Multiple-length-scale deformation analysis in a thermoplastic polyurethane

Thermoplastic polyurethane elastomers enjoy an exceptionally wide range of applications due to their remarkable versatility. These block co-polymers are used here as an example of a structurally inhomogeneous composite containing nano-scale gradients, whose internal strain differs depending on the length scale of consideration. Here we present a combined experimental and modelling approach to the hierarchical characterization of block co-polymer deformation. Synchrotron-based small- and wide-angle X-ray scattering and radiography are used for strain evaluation across the scales. Transmission electron microscopy image-based finite element modelling and fast Fourier transform analysis are used to develop a multi-phase numerical model that achieves agreement with the combined experimental data using a minimal number of adjustable structural parameters. The results highlight the importance of fuzzy interfaces, that is, regions of nanometre-scale structure and property gradients, in determining the mechanical properties of hierarchical composites across the scales

Multiple-length-scale deformation analysis in a thermoplastic polyurethane

Thermoplastic polyurethane elastomers enjoy an exceptionally wide range of applications due to their remarkable versatility. These block co-polymers are used here as an example of a structurally inhomogeneous composite containing nano-scale gradients, whose internal strain differs depending on the length scale of consideration. Here we present a combined experimental and modelling approach to the hierarchical characterization of block co-polymer deformation. Synchrotron-based small- and wide-angle X-ray scattering and radiography are used for strain evaluation across the scales. Transmission electron microscopy image-based finite element modelling and fast Fourier transform analysis are used to develop a multi-phase numerical model that achieves agreement with the combined experimental data using a minimal number of adjustable structural parameters. The results highlight the importance of fuzzy interfaces, that is, regions of nanometre-scale structure and property gradients, in determining the mechanical properties of hierarchical composites across the scales

Multiscale synchrotron scattering studies of the temperature-dependent changes in the structure and deformation response of a thermoplastic polyurethane elastomer

The distinct molecular architecture and thermomechanical properties of polyurethane block copolymers make them suitable for applications ranging from textile fibers to temperature sensors. In the present study, differential scanning calorimetry (DSC) analysis and macroscopic stress relaxation measurements are used to identify the key internal processes occurring in the temperature ranges between −10 °C and 0 °C and between 60 °C and 70 °C. The underlying physical phenomena are elucidated by the small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) study of synchrotron beams, allowing the exploration of the structure-property relationships as a function of temperature. In situ multiscale deformation analysis under uniaxial cyclic thermomechanical loading reveals a significant anomaly in the strain evolution at the nanoscale (assessed via SAXS) in the range between −10 °C and 0 °C owing to the ‘melting’ of the soft matrix. Furthermore, WAXS measurement of crystal strain within the hard regions reveals significant compressive residual strains arising from unloading at ∼60 °C, which are associated with the dynamic shape memory effect in polyurethane at these temperatures

Operando observation of the Taylor cone during electrospinning by multiple synchrotron X-ray techniques

Electrospinning has introduced a powerful means of fabricating polymer nanofibres into the broader realm of nanotechnology and polymer science. It has attracted considerable attention due to its outstanding versatility and numerous applications, such as the incorporation of nanoparticles within the fibres. The Taylor cone formed at the tip of the syringe that delivers the solution (or melt) plays an important role in controlling the structure, and thus the mechanical and functional properties of the fibres produced. Characterising the dynamic processes that occur within the cone is a challenging experimental task. In this study, operando synchrotron X-ray techniques were used to observe the Taylor cone formed during electrospinning. The combination of imaging with spatially resolved mapping by small angle and wide angle X-ray scattering provides a wealth of information about the cone exterior shape, surface orientation and inner morphology. This express note illustrates the rich body of data that can be collected using multi-modal X-ray imaging and scattering setup. From the observed patterns it is possible to extract information concerning particle density and flow patterns that persist within the Taylor cone