Synchrotron X-ray micro-tomography at the Advanced Light Source: Developments in high-temperature in-situ mechanical testing

Abstract

Synchrotron X-ray micro-tomography at the Advanced Light Source: Developments in high-temperature in-situ mechanical testing Abstract. At the Advanced Light Source (ALS), Beamline 8.3.2 performs hard X-ray microtomography under conditions of high temperature, pressure, mechanical loading, and other realistic conditions using environmental test cells. With scan times of 10s-100s of seconds, the microstructural evolution of materials can be directly observed over multiple time steps spanning prescribed changes in the sample environment. This capability enables in-situ quasistatic mechanical testing of materials. We present an overview of our in-situ mechanical testing capabilities and recent hardware developments that enable flexural testing at high temperature and in combination with acoustic emission analysis. IntroductionAs the use of advanced structural materials, such as carbon fiber composites and ceramic matrix composites (CMC), expand in aerospace, turbine, nuclear, and other engineering disciplines, there is a growing need for understanding the response of these materials' microstructure to their operational environments through high resolution imaging and in-situ testing. Beamline 8.3.2 at the Advanced Light Source (ALS) specializes in synchrotron hard X-ray micro-computedtomography (µCT) [1,2]. With µCT, transmission radiographs of an object are taken from multiple angles and are then used to computationally reconstruct a 3D image of the object's internal structure. The high X-ray flux from synchrotron sources like the ALS uniquely enable high-speed micro-scale X-ray imaging and tomography. At 8.3.2, µCT scans typically require 10s-100s of seconds to acquire high-resolution (0.6 µm/pixel) data sets. With short acquisition timescales, relative to other lab-based µCT instruments, synchrotron tomography is well suited for in-situ mechanical testing materials. Analysis of advanced structural materials exposed to incrementally increasing loads can provide detailed knowledge of how material microstructure evolves under realistic loading and failure conditions.

High-throughput quantification of quasistatic, dynamic and spall strength of materials across 10 orders of strain rates

“…Microtensile, microcantilever, and micropillar tests and their counterparts at the nanoscale have allowed researchers to carry out site-specific or volume-specific experiments and obtain the attendant mechanical response ( 3–5 ). These experiments have also been coupled with various diagnostic tools such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and other X-ray or beamline instruments that offer insights into deformation mechanisms and in situ tracking of key parameters such as texture/precipitate evolution, extent of slip behavior, and twin volume fractions ( 6–8 ) in metals.…”

Validation of Deep Learning Segmentation of CT Images of Fiber-Reinforced Composites

“…X-ray micro-computed tomography (µCT) has been widely adopted to investigate internal microstructures and damage of multi-phase structural materials such as fiberreinforced composites [1][2][3][4][5][6][7][8][9][10]. In situ µCT experiments generate multiple 3D images, each consisting of 2000 slices (~30 gigabytes).…”

The hard x-ray nanotomography microscope at the advanced light source

“…[3][4][5] This has been employed to great effect in materials science research and development, with several notable micro-scale computed tomography (µCT) beamlines operating around the world. [6][7][8][9][10][11] Typical µCT systems image direct projections using rectilinear propagation from the sample to detector, where the spatial resolution of the scintillator detector is limited to 0.5 -1.0 um by depth of focus issues 12 associated with the visible light optical microscope objectives used to project the scintillator image onto a pixelated detector. NanoCT systems typically require x-ray zone plates as these optics, when fabricated to modern standards, have inherently higher spatial resolution compared to scintillators used in µCT systems.…”