Wire-Based Additive Manufacturing of Ti-6Al-4V Using Electron Beam Technique.

Electron beam freeform fabrication is a wire feed direct energy deposition additive manufacturing process, where the vacuum condition ensures excellent shielding against the atmosphere and enables processing of highly reactive materials. In this work, this technique is applied for the α + β-titanium alloy Ti-6Al-4V to determine suitable process parameter for robust building. The correlation between dimensions and the dilution of single beads based on selected process parameters, leads to an overlapping distance in the range of 70%-75% of the bead width, resulting in a multi-bead layer with a uniform height and with a linear build-up rate.

Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures.

The physical properties of polycrystalline materials depend on their microstructure, which is the nano- to centimeter scale arrangement of phases and defects in their interior. Such microstructure depends on the shape, crystallographic phase and orientation, and interfacing of the grains constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF 3DND).

The Dual Function of Orchid Bee Ocelli as Revealed by X-Ray Microtomography.

Visually guided flight control in the rainforest is arguably one of the most complex insect behaviors: illumination varies dramatically depending on location [1], and the densely cluttered environment blocks out most of the sky [2]. What visual information do insects sample for flight control in this habitat? To begin answering this question, we determined the visual fields of the ocelli-thought to play a role in attitude stabilization of some flying insects [3-5]-of an orchid bee, Euglossa imperialis. High-resolution 3D models of the ocellar system from X-ray microtomography were used for optical ray tracing simulations.

In situ hydrogen loading on zirconium powder.

For the first time, various hydride phases in a zirconium-hydrogen system have been prepared in a high-energy synchrotron X-ray radiation beamline and their transformation behaviour has been studied in situ. First, the formation and dissolution of hydrides in commercially pure zirconium powder were monitored in real time during hydrogenation and dehydrogenation, then whole pattern crystal structure analysis such as Rietveld and Pawley refinements were performed. All commonly reported low-pressure phases presented in the Zr-H phase diagram are obtained from a single experimental arrangement.

In situ reduction study of cobalt model Fischer-Tropsch synthesis catalysts.

Fischer-Tropsch (FT) synthesis is an important process to manufacture hydrocarbons and oxygenated hydrocarbons from mixtures of carbon monoxide and hydrogen (syngas). The catalysis process occurs on, for example, cobalt metal surfaces at elevated temperatures and pressures. A fundamental understanding of the reduction pathway of supported cobalt oxides, and the intermediate species present during the activation, can assist in developing improved industrial supported cobalt catalysts.

2D mapping of texture and lattice parameters of dental enamel.

We have used synchrotron X-ray diffraction to study the texture and the change in lattice parameter as a function of position in a cross section of human dental enamel. Our study is the first to map changes in preferred orientation and lattice parameter as a function of position within enamel across a whole tooth section with such high resolution. Synchrotron X-ray diffraction with a micro-focused beam spot was used to collect two-dimensional (2D) diffraction images at 150 microm spatial resolution over the entire tooth crown.