This page contains a Flash digital edition of a book.
Far-Field High-Energy Diffraction Microscopy: A Non-Destructive Tool for Characterizing the Microstructure and Micromechanical State of Polycrystalline Materials


Jun-Sang Park , 1 * Xuan Zhang , 2 Peter Kenesei , 1 Su Leen Wong , 3 Meimei Li , 2


and Jonathan Almer 1 1 X-ray Science Division , Argonne National Laboratory , 9700 S Cass Avenue , Lemont IL 60439 2 Nuclear Engineering Division , Argonne National Laboratory , 9700 S. Cass Ave. , Lemont IL 60439 3 Max-Planck-Institut fur Eisenforschung GmbH , Max-Planck-Straße 1 , 40237 , Düsseldorf , Nordrhein-Westfalen , Germany * parkjs@aps.anl.gov


Abstract: A suite of non-destructive, three-dimensional (3D) microscopy techniques using high-energy synchrotron X-rays has been developed over the past decade. These have been used to characterize microstructures and micromechanical states of various polycrystalline materials. Several sample environments compatible with these 3D microscopy techniques have come on-line to enable in situ measurements. This article describes the far-fi eld high-energy diffraction microscopy (FF-HEDM) technique implemented at the 1-ID beamline of the Advanced Photon Source. Examples presented illustrate how FF-HEDM can be used to deepen our understanding of structure- property-processing relationships in polycrystalline materials.


Introduction T e ability to non-destructively map three-dimensional (3D) microstructures and their evolution following external stimuli such as load or heat is of great interest to the materials science and engineering community. As described in a recent review article [ 1 ], microscopy techniques employing visible light or electron beams have been used extensively to characterize material systems so that their properties can be predicted from their microstruc- tures. With these approaches, a polycrystalline sample is typically mapped in 2D, and a series of 2D maps are combined to create a 3D view of the microstructure. Taking advantage of various contrast mechanisms, tomography techniques have also been used to map microstructures in 3D [ 2 ]. While tomography techniques are non-destructive and provide views of the complex internal structures of materials, these methods are typically insensitive to crystallographic orientations in the grain structure that is oſt en related to material properties [ 3 ].


Spatial Resolution


In the past decade, several non-destructive 3D microscopy techniques using high-energy synchrotron X-rays have come on-line [ 4 – 8 ]. T ese techniques are capable of characterizing the microstructure of a relatively large polycrystalline aggregate at the grain length scale with sensitivity to crystallographic orientation. Combined with suitable experimental apparatus, these techniques can be performed in situ ; thus, the evolution of a polycrystalline aggregate microstructure can be tracked while external stimuli such as load, electric current, or heat are applied [ 9 – 12 ]. T is experimental capability opens new opportunities for scientists and engineers to deconvolve and understand the complex relationships between processing history, grain structure, and component perfor- mance. Experimental data obtained from these techniques can be used to validate and calibrate physically based material models crucial to eff orts such as Integrated Computational Materials Engineering (ICME) and the Materials Genome Initiative (MGI). In this article we describe the far-fi eld high-energy diff raction microscopy (FF-HEDM) setup at the 1-ID beamline of the Advanced Photon Source (APS) at Argonne National Laboratory. Examples are presented of how FF-HEDM data can be used to validate physically based models and to understand the intricate relationship between structure, processing, and properties.


Far-Field High-Energy Diffraction Microscopy at the APS


High-energy synchrotron radiation . X-rays from synchro- trons with energies greater than 50 keV have a unique set of characteristics that make them an ideal probe for characterizing


Table 1 : HEDM techniques available at the APS 1-ID beamline [ 19 ]. Experimental Technique Near-field


high-energy diffraction microscopy (NF-HEDM)


Far-field


high-energy diffraction microscopy (FF-HEDM)


Very-far-field high-energy diffraction microscopy (VFF-HEDM)


36


∼ 1 μ m spatial resolution; 0.1  –0.01  angular resolution


∼ 10 μ m spatial resolution; 0.1  –0.01  crystallographic orientation resolution; 10 −4 strain resolution


~0.01angular resolution Remarks


Area detector (1.5 μ m square pixels covering ~3.1 mm × ~3.1 mm area) placed ~10 mm away from the sample. Analogous to non-destructive 3D electron backscatter diffraction view of a polycrystalline aggregate using a line focused beam [ 13 – 14 ]. Does not provide strain information.


Area detector (200 μ m square pixels covering ~410 mm × ~410 mm area) placed ~1 m away from the sample. Non-destructive 3D map of the centers of masses, crystallographic orientations, radii, and elastic strain tensors of the grains in a polycrystalline aggregate [ 8 ].


Area detector (~60 μ m pixels covering ~50 mm × ~30 mm area) placed ~5 m away from the sample. Non-destructive reciprocal space mapping of individual grains in a polycrystalline aggregate [ 18 ].


doi: 10.1017/S1551929517000827 www.microscopy-today.com • 2017 September


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76