A5021196205- Additive Manufacturing Materials and Processes
- Diamond and Carbon-based Materials Research
- Ion-surface interactions and analysis
- Welding Techniques and Residual Stresses
- Additive Manufacturing and 3D Printing Technologies
- Semiconductor materials and devices
- Nuclear Materials and Properties
- Laser Material Processing Techniques
- Advanced Electron Microscopy Techniques and Applications
- High Entropy Alloys Studies
- Advanced Surface Polishing Techniques
- Radioactive element chemistry and processing
- Electronic and Structural Properties of Oxides
- High-pressure geophysics and materials
- Nuclear materials and radiation effects
- Electron and X-Ray Spectroscopy Techniques
- Advanced X-ray and CT Imaging
- Integrated Circuits and Semiconductor Failure Analysis
- Fluid Dynamics and Thin Films
- Force Microscopy Techniques and Applications
- Metal and Thin Film Mechanics
- Titanium Alloys Microstructure and Properties
- Laser-induced spectroscopy and plasma
- Silicon and Solar Cell Technologies
- Magnesium Alloys: Properties and Applications
Lawrence Livermore National Laboratory
2015-2025
SUNY Polytechnic Institute
2019
University of Technology Sydney
2007-2017
University of Technology
2016
Universidad de Valladolid
2010
Abstract Laser powder bed fusion additive manufacturing is an emerging 3D printing technique for the fabrication of advanced metal components. Widespread adoption it and similar technologies hampered by poor understanding laser-metal interactions under such extreme thermal regimes. Here, we elucidate mechanism pore formation liquid-solid interface dynamics during typical laser conditions using in situ X-ray imaging multi-physics simulations. Pores are revealed to form changes scan velocity...
Circumventing spatter Laser powder bed fusion is an additive manufacturing technique that laser-melts layer by to build a three-dimensional (3D) part. Khairallah et al. used experiments and multiphysics model determine the origin of melt defect formation degrade properties built parts (see Perspective Polonsky Pollock). Informed modulation laser power important avoid disturbing creating shadowing. This reduces pore formations leads more uniform 3D-printed parts. Science , this issue p. 660 ;...
Advanced in situ characterization is essential for determining the underlying dynamics of laser-material interactions central to both laser welding and rapidly expanding field additive manufacturing. Traditional techniques leave a critical experimental gap understanding complex subsurface fluid flow metal evaporation inherent laser-induced heating metal. Herein, ultra-high-speed transmission X-ray imaging revealed be bridging this information gap, particularly via comparison with validation...
In situ X-ray-based measurements of the laser powder bed fusion (LPBF) additive manufacturing process produce unique data for model validation and improved understanding. Synchrotron X-ray imaging diffraction provide high resolution, bulk sensitive information with sufficient sampling rates to probe melt pool dynamics as well phase microstructure evolution. Here, we describe a laboratory-scale LPBF test designed accommodate experiments at synchrotron source during operation. We also present...
Abstract Laser powder bed fusion (LPBF) is a method of additive manufacturing characterized by the rapid scanning high powered laser over thin metallic to create single layer, which may then be built upon form larger structures. Much melting, resolidification, and subsequent cooling take place at much higher rates with thermal gradients than in traditional metallurgical processes, this occurring below surface. We have used situ speed X-ray diffraction extract subsurface following...
When tungsten is processed by laser powder bed fusion additive manufacturing, the combination of high residual stresses and tungsten's inherent ductile-to-brittle transition leads to a network microcracks. While preheating widely accepted as most efficient way reduce in additively manufactured parts, thus far it has proven ineffective completely eliminating microcracking tungsten. In addition preheating, changing alloy composition an increasingly popular approach circumvent cracking. This...
Laser powder bed fusion (LPBF) is a powerful tool for additive manufacturing (AM) of metal components. However, fabricating components with overhanging features using LPBF remains challenge. Overhangs suffer from dimensional inaccuracies, high surface roughness, and agglomerated material or dross. These parts often do not meet engineering requirements are discarded reprinted until met, redesigned to avoid overhangs. Printing flat overhang especially challenging due the long, unsupported that...
Laser powder bed fusion (LPBF) metal additive manufacturing provides distinct advantages for aerospace and biomedical applications. However, widespread industrial adoption is limited by a lack of confidence in part properties driven an incomplete understanding how unique process parameters relate to defect formation ultimately mechanical properties. To address that gap, high‐speed X‐ray imaging used probe subsurface melt pool dynamics void‐formation mechanisms inaccessible other monitoring...
Laser powder bed fusion (LPBF) additive manufacturing and laser welding are powerful metal processing techniques with broad applications in advanced sectors such as the biomedical aerospace industries. One common process variable that can tune laser-material interaction dynamics these two is adjustment of composition pressure atmosphere which conducted. While some physical mechanisms governed by ambient well known from literature, it remains unclear how extend to distinct conditions LPBF. In...
Detonation nanodiamond (DND) is known to form aggregates that significantly reduce their unique nanoscale properties and require postprocessing separate. How when DND an important question has not been answered experimentally could provide the foundation for approaches limit aggregation. To answer this question, time-resolved small-angle X-ray scattering was performed during detonation of high-explosives are expected condense particulates in diamond, graphite, liquid regions carbon phase...
Metal parts produced by laser powder bed fusion (LPBF) additive manufacturing exhibit characteristic microstructures comparable to those observed in welding. The primary cause of this microstructure is rapid, localized heating and cooling cycles, which result extreme thermal gradients where material solidification followed fast the solid state. final mechanical performance are also influenced pore formation caused melt pool fluid dynamics. Here, we use high speed, situ X-ray diffraction...
Abstract We present our recent development of an integrated mesoscale digital twin (DT) framework for relating processing conditions, microstructures, and mechanical responses additively manufactured (AM) metals. In particular, focusing on the laser powder bed fusion technique, we describe how individual modeling simulation capabilities are coupled to investigate control AM microstructural features at multiple length time scales. review prior case studies that demonstrate schemes, in which...
Controlled fabrication of semiconductor nanostructures is an essential step in engineering high performance photonic and optoelectronic devices. Diamond particular has recently attracted considerable attention as a promising platform for quantum technologies, photonics resolution sensing applications. Here we demonstrate the optically active, functional diamond structures using gas-mediated electron beam induced etching (EBIE). The technique achieves dry chemical at room temperature through...
We present a direct-write chemical technique for controlling the charge state of near-surface nitrogen vacancy centers (NVs) in diamond by surface fluorination. Fluorination H-terminated is realized electron beam stimulated desorption H2O presence NF3 and verified with environmental photoyield spectroscopy (EPYS) photoluminescence (PL) spectroscopy. PL spectra shallow NVs H- F-terminated nanodiamonds show expected dependence NV on their energetic position respect to Fermi-level. EPYS reveals...
Abstract In situ monitoring is required to improve the understanding and increase reliability of additive manufacturing methods such as laser powder bed fusion (LPBF). Current diagnostic for LPBF capture optical images, X-ray radiographs, or measure emission thermal acoustic signals from component. Herein, a methodology based on electrons - thermionic metal surface during proposed which can resolve laser-material interaction dynamics. The high sensitivity temperature morphology revealed...
Abstract Recent advances in focused ion beam technology have enabled high-resolution, maskless nanofabrication using light ions. Studies with ions to date have, however, on milling of materials where sub-surface damage does not inhibit device performance. Here we report single crystal diamond a oxygen Material quality is assessed by Raman and luminescence analysis reveals that the layer generated can be removed non-intrusive post-processing methods such as localised electron induced chemical etching.
The rendering in the background shows a metal component being manufactured through laser powder bed fusion additive manufacturing. film strip contains frames from high-speed X-ray imaging revealing previously unseen void defect formation during build which furthers understanding of material properties and performance these components. Further details can be found article number 1900455 by Johanna Nelson Weker co-workers.
Laser powder bed fusion (LPBF) is a highly dynamic multi-physics process used for the additive manufacturing (AM) of metal components. Improving understanding and validating predictive computational models require high-fidelity diagnostics capable capturing data in challenging environments. Synchrotron x-ray techniques play vital role validation as they are only situ diagnostic imaging sub-surface melt pool dynamics microstructure evolution during LPBF-AM. In this article, laboratory scale...
Additive friction stir deposition (AFSD) is a solid-state metal additive manufacturing technique, which utilizes frictional heating and plastic deformation to create large deposits parts. Much like its cousin processes, welding processing, AFSD has seen the most compatibility use with lower-temperature metals, such as aluminum; however, there growing interest in higher-temperature materials, titanium steel alloys. In this work, we explore of an ultrahigh-temperature refractory material,...
Hydrogel infused additive manufacturing (HIAM) is an emerging technique for the of ceramics and metals. Distinct from slurry- or powder-based techniques, a hydrogel scaffold obtained in the...