Coloring and distortion variants of the bcc packing and for the aristotypes BaAl4 and CeMg2Si2

The huge number of intermetallic structure types with many representatives calls for structural systemization. The combination of crystal chemistry with group theory is an efficient tool for such systemization and can be displayed in a concise and compact way via group-subgroup schemes. The present overview deals with such group-subgroup schemes (Bärnighausen trees) for coloring and distortion variants of the bcc packing as well as superstructures that derive from the aristotypes BaAl4 and CeMg2Si2.

Atomically dispersed Ru in Pt3Sn intermetallic alloy as an efficient methanol oxidation electrocatalyst

A Ru–Pt3Sn NC catalyst composed of atomically dispersed Ru atoms shows enhanced performance in methanol electroxidation, which is ascribed to the stable intermetallic structure and active surface structure, as well as the synergy among Pt, Sn and Ru.

MEASUREMENT OF THE ABSORPTION-BASED HYDROGEN STORAGE CAPACITY OF Ti0.95Zr0.05Cr0.8Mn0.8V0.2Ni0.2 ALLOY

The article describes potential application of the BCC alloy Ti0.95Zr0.05Cr0.8Mn0.8V0.2Ni0.2 in the hydrogen absorption process. It deals with the measurements of the PCI (Pressure Concentration Isotherm) characteristics applying the volumetric method. With regard to the fact that it is an indirect measurement method, the thermodynamic description was analysed in details and subsequently used to identify the weight capacity of the stored hydrogen. The article presents a detailed description of the procedure for measuring the free volume of the measuring equipment using helium which is able to penetrate into pores and apertures with the size of only a few nanometres but does not participate in the absorption into the intermetallic structure of the alloy. The hydrogen absorption into the tested alloy was initiated by repeatedly performed activation of the alloy surface. The final section of the article presents the examination of the cyclic stability of the absorption-desorption cycle within the repeated monitoring of the maximum weight capacity of the stored hydrogen.

Polyol Process Coupled to Cold Plasma as a New and Efficient Nanohydride Processing Method: Nano-Ni2H as a Case Study

An alternative route for metal hydrogenation has been investigated: cold plasma hydrogen implantation on polyol-made transition metal nanoparticles. This treatment applied to a challenging system, Ni–H, induces a re-ordering of the metal lattice, and superstructure lines have been observed by both Bragg–Brentano and grazing incidence X-ray diffraction. The resulting intermetallic structure is similar to those obtained by very high-pressure hydrogenation of nickel and prompt us to suggest that plasma-based hydrogen implantation in nanometals is likely to generate unusual metal hydride, opening new opportunities in chemisorption hydrogen storage. Typically, almost isotropic in shape and about 30 nm sized hexagonal-packed Ni2H single crystals were produced starting from similarly sized cubic face-centred Ni polycrystals.

Changing the structure and properties of hot-dip zinc coatings using diffusion annealing

Zinc coatings are widely used to protect steel goods from corrosion. The physics of methods of zinc applying to steel determines the coating morphology. Hot-dip zinc and thermodiffusion coatings are produced on steel by a diffusion mechanism and contain intermetallic phases according to the Fe-Zn diagram; however, they have different phase morphology, corrosion resistance, and consequently, different operating corrosive media. Thermodiffusion coatings have the highest corrosion resistance. However, their applying technique imposes a restraint on the dimensions of goods due to the small size of a chamber, and it requires much more time (several hours) compared to hot-dip zinc coatings applying for several minutes. In this respect, the authors suggest using the diffusion annealing of hot-dip galvanized goods to produce the entire intermetallic structure of the coating. The goal of the paper was to study the influence of the diffusion annealing modes on the microstructure and properties of hot-dip zinc coatings. The study showed the changes in the microstructure and elemental composition of the zinc coating phases as the result of soaking at the temperatures of 500 and 600 °С for 5 and 10 minutes. The authors researched the influence of annealing modes on the porosity of a coating and its microhardness. The coatings were quickly tested for corrosion resistance in the initial state and after thermal treatment. As a result of diffusion annealing, zinc coating becomes completely intermetallic, more homogeneous; its chemical composition becomes uniform. The study identified that to obtain the balance of physical-mechanical and technological properties, it is recommended to use the diffusion annealing mode with a temperature of 500 °С and soaking in a furnace for 5 minutes.

Synthesis and effect of Misch metal on mechanical properties of conventional cast Mg–Al–Zn–Sn–Pb alloy system

Magnesium alloys are increasingly accepted in automobile industry owing to their greater strength-to-weight ratio. These qualities lead to less vehicle weight and better fuel economy. Therefore, in the present work an effort has been made to develop a new Mg alloy system that exhibits greater ductility together with greater mechanical strength. Misch metal is added in Mg-based alloys to investigate the changes in mechanical properties. The microstructure of alloys Mg–4Al–3Zn–3Sn–3Pb (H1) and Mg–4Al–3Zn–3Sn–3Pb–0.5MM (H2) are dendritic in nature while for Mg–3Zn–3Sn–3Pb–2Si (H3) the “Chinese script” Mg2Si intermetallic structure was obtained. The ultimate tensile strength and elongation of Mg–4Al–3Zn–3Sn–3Pb–0.5MM (H2) alloy are about 40% and 100 % higher than that of H3 alloy. The ultimate tensile strength, yield strength, and percentage elongation of H2 alloy are 170 MPa, 44 MPa, and 3.4%, respectively.