Characterizing solute hydrogen and hydrides in pure and alloyed titanium at the atomic scale

Ti has a high affinity for hydrogen and are typical hydride formers . Ti -hydride are brittle phases which probably cause premature failure of Ti -alloys. Here, we used atom probe tomography and electron microscopy to investigate the hydrogen di stribution in a set of specimens of commercially pure Ti , model and commercial Ti -alloys. Although likely partly introduced during specimen preparation with the focused- ion beam, we show formation of Ti-hydrides along α grain boundaries and α / β phase boundaries in commercial pure Ti and α + β binary model alloys . No hydrides are observed in the α phase in alloys with Al addition or quenched-in Mo supersaturation

An investigation of hydrogen/microstructure interaction in complex nickel-based alloys : Multi-scale detection and embrittlement mechanisms

Precipitation-hardened nickel-based alloys are established as standard materials for key applications in oil and gas industry. Alloy 718 (UNS N07718) is one of the most commonly used commercial alloys in this field. Despite the superior corrosion resistance and mechanical properties, high strength Ni-based alloys show susceptibility to hydrogen embrittlement. To improve material’s resistance to hydrogen embrittlement, it is important to have a better understanding of the mechanisms/factors, which affect the hydrogen-related degradation of mechanical properties. Hydrogen embrittlement of alloy 718 was investigated by in situ tensile testing under hydrogen charging, placing the focus on the underlying hydrogen-related deformation mechanisms and cracking. Hydrogen-induced cracking was studied with the correlative use of electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI) analyses to establish correlations between the microstructure, crack initiation sites, and crack propagation pathways. The material was investigated at different strength levels: after solution annealing (as quenched state) and after age-hardening at 780 °C, to elucidate the contributions of stress or strain to the cracking mechanisms. It was found that the deformation modes affecting the stress and/or strain localization play an important role in hydrogen-related cracking mechanisms. Material in over-aged state (aged at 870 °C) with different precipitation conditions of the δ-phase was also investigated to check the effect of the grain boundary δ-phase in crack propagation. To further elucidate the role of the δ-Ni3Nb intermetallic precipitates in hydrogen embrittlement, a binary Ni-Nb model alloy was used. The approach of conducting correlative measurements using thermal desorption spectroscopy (TDS), silver decoration, scanning kelvin probe force microscopy (SKPFM), and secondary ion mass spectrometry (SIMS), enabled performing multiscale mapping of hydrogen in the microstructure, ranging from the macroscale down to few-nanometers. With this joint and spatially resolving approach the microstructure- and time-dependent distribution and release rate of hydrogen were observed with high spatial and temporal resolution. By correlating the obtained results with mechanical testing the hydrogen-assisted failure mechanism was discussed

Ergonomics in Healthcare system-Human Factors models: a review article

Introduction: The healthcare system is one of the largest sectors in most countries and is a socio-technical system in which people play a preponderant role. Nowadays medical work systems are facing three major challenges: 1) Healthcare costs, 2) Quality and patient demands and 3) complexity of healthcare. These problems show the necessity of applying ergonomic models in the healthcare sector. The aim of this study was to review the practical ergonomic models in healthcare system.   Material and method: For this review article, the authors searched through ScienceDirect, PubMed, ProQuest internet databases from 2005-2014 using the following keywords: Healthcare, Ergonomics, Human factors and model.   Result: Overall, 85 articles were reviewed. By evaluating articles' titles, 30 articles related to the study subject were chosen. Then, reviewing the abstracts resulted in 15 articles and in the final step 5 full-text articles were selected which described practical models of ergonomics in healthcare: 1) SEIPS, 2) DIAL-F, 3) Extended Patient-Staff-Machine-Interaction, 4) Adapted Medical-Task and 5) Recursive Hierarchical Task-Process-Task-Model.   Conclusion: Most of the published studies emphasize on application of ergonomic models in healthcare centers since these models may reduce their problems. These ergonomics approaches support patient-centered treatment processes, user-oriented design of medical environments, efficient utilization of resources and increase motivation of clinical staff