Probing Novel Microstructural Evolution Mechanisms in Aluminum Alloys Using 4D Nanoscale Characterization

Abstract

Dispersions of nanoscale precipitates in metallic alloys have been known to play a key role in strengthening, by increasing their strain hardenability and providing resistance to deformation. Although these phenomena have been extensively investigated in the last century, the traditional approaches employed in the past have not rendered an authoritative microstructural understanding in such materials. The effect of the precipitates' inherent complex morphology and their 3D spatial distribution on evolution and deformation behavior have often been precluded. This study reports, for the first time, implementation of synchrotron-based hard X-ray nanotomography in Al-Cu alloys to measure kinetics of different nanoscale phases in 3D, and reveals insights behind some of the observed novel phase transformation reactions. The experimental results of the present study reconcile with coarsening models from the Lifshitz-Slyozov-Wagner theory to an unprecedented extent, thereby establishing a new paradigm for thermodynamic analysis of precipitate assemblies. Finally, this study sheds light on the possibilities for establishing new theories for dislocation-particle interactions, based on the limitations of using the Orowan equation in estimating precipitation strengthening.

Three-dimensional alteration of neurites in schizophrenia

“…In this study, we analyzed brain tissue structures of schizophrenia patients and control cases with synchrotron radiation nanotomography. 18,19 X-ray microtomography and nanotomography [20][21][22][23][24][25] can visualize three-dimensional opaque objects with nearly isotropic resolution. 26 Its reconstruction process does not involve any deformation correction, and hence, the obtained image reproduces the actual three-dimensional structures.…”

Precipitation kinetics in metallic alloys: Experiments and modeling

“…When studying precipitates of relatively large size (>10-100nm), 3D characterization becomes accessible using in-situ X-ray tomography [55].…”

“…The description of the transition between these structures is obviously complex, but was first simplified to a criterion on precipitate size [197], before recent phase-field modelling has been able to describe the occurrence of the internal displacive transformation [198]. Another classic case is the evolution of GPI zones in Al-Cu alloys (a single atomic plane of Cu) into GPII zones (two atomic planes), which simply requires adding atoms to the initial structure, followed by more abrupt changes in structure towards the ' [199] and  phases [55]. An interesting case of this in-situ transformation is when the metastable state contains some crystallographic building blocks of the precipitate which will form from it.…”

Unraveling the Mechanisms of the Apis mellifera Honeycomb Construction by 4D X‐ray Microscopy

“…3D X-ray microscopy (XRM) is a powerful tool that provides an unprecedented means of studying and quantifying the microstructure of the honeycomb non-destructively. [14][15][16][17] Furthermore, using a time-resolved approach in which scans are interrupted to apply an external stimulus to the sample, [18,19] one could systematically understand the step-by-step process by which honey bees construct comb. Using our time-resolved XRM technique, we investigated the construction of honeycomb in 4D (time-resolved) for the first time.…”