Search

In the present study, Mg–5Ni and Mg–15Ni alloys are prepared, and their (de)hydrogenation properties are investigated by thermal desorption spectroscopy (TDS). A new hydrogenation condition is developed to improve the hydrogen uptake properties of the Mg–Ni alloy. It is found that the hydrogen absorption and thermal desorption properties of both alloys are extremely sensitive to the presence of 3% O 2 in the hydrogenation environment. Although O₂ accelerates hydrogen absorption, it lowers the desorption temperature and reduces the hydrogen storage capacity of the Mg–Ni alloy by consuming Mg₂Ni if it is added in every cycle. The hydrogen storage capacity of Mg–Ni alloys can be significantly increased by adding oxygen only in the second cycle instead of in all cycles. In the early stages of hydrogenation, only two TDS peaks are observed, while in later cycles a new peak appears at higher temperatures. These peaks correspond to the decomposition of Mg₂NiH₄ (peak 1), MgH₂ (peak 2), and the release of hydrogen from the bulk material (peak 3). It is also evident that the Mg–15Ni sample has a better hydrogen storage capacity than the Mg–5Ni sample. • Studying (de-)hydrogenation properties of Mg–Ni alloys in presence of 3% O 2. • O 2 accelerates hydrogen absorption and lowers the hydrogen desorption temperature. • Adding 3% O 2 only in 2nd cycle improves hydrogen storage capacity of Mg–Ni alloys. • In early cycles, two TDS peaks are seen, while in later ones a new peak appears. • The Mg–15Ni sample has a better hydrogen storage capacity than Mg–5Ni. [ABSTRACT FROM AUTHOR]

The quantification of lithium in electron microscopes by energy-dispersive X-ray spectroscopy (EDS) is highly challenging due to the low energy of the characteristic X-rays. Only special windowless detectors can detect Li, yet the sensitivity is suboptimal (i.e., ~20 wt. %). We introduce the use of quantitative backscattered electron microscopy in combination with measurements using a standard EDS sensor to achieve spatially resolved quantification of Li. The method is demonstrated using two Mg-Li alloys with 4 and 20 wt. % Li and good accuracy with a deviation of only ~1.2 wt. % and ~2.5 wt. %, respectively, is achieved. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• Dual-WAAM of a Ti-Fe alloy with eutectoid composition (Ti-Fe15(wt.%)) successfully performed. • As-built microstructure consists of large grains with predominantly β-phase. • On heat treatment fine-scaled α-phase is precipitated associated with an increase in hardness. • Thermal analysis revealed that this decomposition reaction is kinetically controlled by Fe diffusion in the β-phase. • Neither ω- nor intermetallic TiFe phase are observed. Titanium alloys are among the most relevant structural materials for aerospace applications; they can be processed using various additive manufacturing (AM) techniques including wire-based AM. However, conventional alloy systems, such as Ti-6Al-4V, are, from a metallurgical perspective, not optimized for AM. Here, we investigate the effects of alloying Ti with Fe using dual-WAAM to improve the understanding of the effects of the addition of β-eutectoid forming elements on the microstructure. A structural characterization of the material after processing reveals the microstructure in the as-built condition to primarily consist of β-phase from which α-phase is precipitated upon a heat-treatment, resulting in a substantial increase in hardness. [ABSTRACT FROM AUTHOR]

[Display omitted] We present a combined experimental and computational investigation of phase stability and mechanical properties in the Al-Cu-Mg-Zn quaternary system. Samples containing different relative compositions were prepared using magnetron sputtering and investigated by electron microscopic and X-ray based methods. To classify the technical relevance of the samples, the indentation hardness was measured. The phase stability was studied computationally using a cluster expansion approach based on density functional theory (DFT) methods in a comprehensive screening of the structural and stoichiometric configuration space. Upon decreasing Cu concentration, a transition from an FCC to a mixed FCC/BCC crystal system and significant changes in the mechanical properties depending on Valence Electron Concentration (VEC) and atomic size differences (δ r) was observed experimentally. The corresponding crystallographic phases were assigned by XRD and the experimentally observed phase transition was confirmed by the computational screening of formation energies. Since to date, quaternary complex light metal alloy systems cannot be reliably predicted, this is an important step towards a priori modelling of this class of materials. [ABSTRACT FROM AUTHOR]