Frontier nonequilibrium materials science enabled by ultrafast electron methods

Abstract

Most innovation in materials science and engineering resides in our ability to understand and control the intimate relationship between the structure of materials and their properties. Conventionally, the only route to discovering innovative new material properties has been to explore the structural and compositional phase space that is accessible at (or near) thermodynamic equilibrium. The characterization, manipulation and, ultimately, control of material properties far from equilibrium offers almost completely untapped possibilities for uncovering novel states and phases of materials. Investigations of materials far from equilibrium require the development of new techniques, which are capable of following dynamic processes in materials with extreme spatiotemporal resolution. Thus, ultrafast electron-based methods have become a major new frontier in materials science due to the capability of following dynamics on time scales as short as femtoseconds with the high spatial resolution and sensitivity afforded by electrons. The articles in this issue provide an exciting cross section of the novel research directions that have been enabled at this frontier. Imaging on ultrafast time scales carries critical information on phase transitions, fundamental processes involved in light-harvesting, magnetic, and plasmonic dynamics, the coupling of electronic and nuclear degrees of freedom in materials and has revealed previously hidden, nonequilibrium metastable states of matter that have no equilibrium analog.

Modelling of Microstructure Formation in Metal Additive Manufacturing: Recent Progress, Research Gaps and Perspectives

“…While solidification studies that centred around thermodynamic equilibrium (or nearequilibrium) were sufficient in the past to trigger innovations in manufacturing, this no longer holds for AM. Therefore, the characterisation, manipulation and, ultimately, control of material properties far from equilibrium offers almost completely untapped possibilities for uncovering novel states and phases of materials [18].…”

“…This can only accelerate the pace at which several of these phenomena are better understood-and potentially tuned to obtain desirable tailored microstructures. Investigations of materials far from equilibrium require the development of new techniques capable of following dynamic processes in materials with extreme spatiotemporal resolution [18]. It is encouraging that new breakthroughs are being reported in the in-situ sensor technologies that can assist the AM community in deepening its knowledge of the nonequilibrium phenomena.…”

“…It is encouraging that new breakthroughs are being reported in the in-situ sensor technologies that can assist the AM community in deepening its knowledge of the nonequilibrium phenomena. For example, recently Siwick et al [18] explained that ultrafast electron-based methods have become a major new frontier in materials science due to the capability of following dynamics on time scales as short as femtoseconds with the high spatial resolution and sensitivity afforded by electrons. Such equipment is likely to be capable of providing information for modellers and experimentalists on phenomena (e.g., phase transitions, metastable states) that hold the key to accurately recreating the solidification processes in AM.…”

“…Other alloys are considered elsewhere, e.g., [16]. Most innovation in materials science and engineering resides in our ability to understand and control the intimate relationship between the structure of materials and their properties [18]. The first step towards achieving such innovation in the sphere of AM involves understanding the relationship between the process parameters and the microstructures they create.…”

Dual-stage structural response to quenching charge order in magnetite

“…Compared with the pervious ultrafast studies on magnetite, we are more interested in the detailed lattice deformations related to the phonon modes in different and longer timescales. In this study, we use ultrashort laser pulses to decouple the electrons and lattice in the far-from-equilibrium state and employ MeV electron pulses to probe the charge ordered state and lattice deformation in the time domain [33,34]. Due to the energy redistribution between electrons and lattice in the photoexcited system, we observed energy flow from the electrons to the lattice.…”