Synthesis and Corrosion Resistance of FeMnNiAlC10 Multi-Principal Element Compound

A multi-principal element FeMnNiAlC10 bulk alloy was produced by vacuum arc melting. The same alloy was sintered as a thin film on a silicon substrate by ion beam sputter deposition. The bulk alloy has a multiphase structure the elements predominantly segregating into iron manganese carbides and nickel aluminium phases. The thin film is amorphous without detectable phase segregations. The absence of segregation is attributed to the film composition and deposition onto substrate at temperature below 400 K. The corrosion resistance of the thin film alloy was evaluated in 3.5% NaCl. The FeMnNiAlC10 thin film alloy has better corrosion resistance than 304SS. The hardness of the thin film was approximately 7.2 ± 0.3 GPa and the reduced Young’s modulus was approximately 103 ± 4.6 GPa. FeMnNiAlC10 thin film could be a good candidate for coating oil and gas extraction soft iron infrastructure.

Archaeological applications of natural gold analyses

Compositional studies of natural gold usually have a geological focus, but are also important in archaeological provenancing. Both methodologies rely on compositional comparison of two sets of samples, one of which is geographically constrained. Here we describe how experiences in gold characterization resulting from geological studies are relevant to archaeology. Microchemical characterization of polished sections of natural gold identifies alloy compositions, alloy heterogeneity and mineral inclusions. Gold from all deposit types shows Cu and Sn values much lower than those recorded during numerous studies of artefacts. Inclusions in artefact gold include various Cu- and Sn-bearing compounds which indicate specific high temperature reactions that could ultimately illuminate the conditions of (s)melting. The use of LA-ICP-MS to generate a wide range of elemental discriminants for provenance studies may be compromised by alloy adulteration and/or unrepresentative analysis of natural/artefact alloys, which are commonly highly heterogeneous at the micron scale. Geological studies normally characterize only the earliest-formed (hypogene) alloy, whereas archaeology-focussed studies should entail analyses of bulk alloy compositions and impurities that may be incorporated during (s)melting. Isotopic-based provenancing alleviates many of these problems but, to date, generates regional rather than locality specific targets. A dual isotopic-compositional approach is recommended.

Mitigating Corrosion Effects of Ti-48Al-2Cr-2Nb Alloy Fabricated via Electron Beam Melting (EBM) Technique by Regulating the Immersion Conditions

The corrosion behavior of newly fabricated γ-TiAl alloy was studied using electrochemical impedance spectroscopy (EIS) and cyclic potentiodynamic polarization (CPP) techniques. The γ-TiAl alloy was produced from powder with compositions of Ti-48Al-2Cr-2Nb processed using electron beam melting (EBM) technique. The corrosion behavior of the bulk alloy was investigated in 1 M HCl solution for different immersion times and temperatures. The experimental results suggest that the fabricated alloy exhibits good resistance to corrosion in acid solution at room temperature. The results also indicate that with an increase in immersion time and solution temperature, the corrosion potential (Ecorr) shifts to a higher positive value, resulting in an increase in corrosion current (jcorr) and consequently a decrease in the corrosion resistance (Rp) of the alloy.

Microstructure, Micro-Mechanical and Tribocorrosion Behavior of Oxygen Hardened Ti–13Nb–13Zr Alloy

In the present work, an oxygen hardening of near-β phase Ti–13Nb–13Zr alloy in plasma glow discharge at 700–1000 °C was studied. The influence of the surface treatment on the alloy microstructure, tribological and micromechanical properties, and corrosion resistance is presented. A strong influence of the treatment on the hardened zone thickness, refinement of the α’ laths and grain size of the bulk alloy were found. The outer hardened zone contained mainly an oxygen-rich Ti α’ (O) solid solution. The microhardness and elastic modulus of the hardened zone decreased with increasing hardening temperature. The hardened zone thickness, size of the α’ laths, and grain size of the bulk alloy increased with increasing treatment temperature. The wear resistance of the alloy oxygen-hardened at 1000 °C was about two hundred times, and at 700 °C, even five hundred times greater than that of the base alloy. Oxygen hardening also slightly improved the corrosion resistance. Tribocorrosion tests revealed that the alloy hardened at 700 °C was wear-resistant in a corrosive environment, and when the friction process was completed, the passive film was quickly restored. The results show that glow discharge plasma oxidation is a simple and effective method to enhance the micromechanical and tribological performance of the Ti–13Nb–13Zr alloy.

Optimization of Anodization Parameters in Ti-30Ta Alloy

The current metallic biomaterial still presents failures associated with the bulk alloy and the interface of material/human body. In previous studies, titanium alloy with tantalum showed the elastic modulus decrease in comparison with that of commercially pure (cp) titanium. In this study, surface modification on Ti-30Ta alloy was investigated. Titanium and tantalum were melted, homogenized, cold-worked by a rotary swaging process and solubilized. The anodization process was performed in electrolyte contained glycerol + NH4F 0.25% at 30 V using seven different durations—4 h, 5 h, 6 h, 7 h, 8 h, 9 h, and 10 h and annealed at 530 °C for 1 h. The surface topography was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) measurements, X-ray diffraction analysis (XRD), and contact angle. From the results, we conclude the time of anodization process influences the shape and morphology of the anodized layer. The 5 h-anodization process produced a smooth and porous surface. The 4-, 6-, 7-, 8-, 9-, and 10-h conditions showed nanotubes morphology. All surfaces are hydrophilic (<90°). Likewise, all the investigated conditions present anatase phase. So, this surface modification presents potential for biomedical application. However, more work needs to be done to better understand the influence of time on the anodization process.

Ultrafine grain recrystallisation of a metastable-β Ti-alloy via conventional thermomechanical processing

Alloys with ultrafine grains (UFG) offer high strength potentially combined with ductility. Until now, producing ultrafine grains in ingot alloys has required either severe plastic deformation techniques or flash annealing, neither of which are scalable to bulk alloy production. In this work, we formed submicronic grains in the metastable β titanium alloy Ti-20Nb-6Zr (at%), using conventional cold rolling and annealing at 823K in a conventional furnace. The cold rolling (298K) transformed the β structure mostly to α” martensite, but if the rolling temperature was raised to 453K, martensite formation was supressed, and no grain refinement occurred during the subsequent similar annealing treatment. Therefore, we attribute the formation of ultrafine grains to a mechanism involving stress-induced martensite and its reverse transformation.

Structure, Magnetic Properties and Magnetization Reversal Processes in Nanocrystalline Pr8Dy1Fe60Co7Mn6B14Zr1Ti3 Bulk Alloy

The present paper presents results concerning on structure, magnetic properties and magnetization reversal processes in the as-cast Pr8Dy1Fe60Co7Mn6B14Zr1Ti3 alloy in the form of 1 mm plate. The XRD studies revealed coexistence of three phases dominant Pr2(Fe,Co)14B and minor �-Fe and Fe3B. The remanence-to-saturation ratio Jr/Js equaled 0.66 and indicated on existence of strong exchange interactions between hard and soft magnetic phases. The analysis of Mrev vs. Mirr dependences, the pinning mechanism was detected in studied alloy.

Structure, Magnetic Properties and Magnetization Reversal Processes in Nanocrystalline Pr8Dy1Fe60Co7Mn6B14Zr1Ti3 Bulk Alloy

The present paper presents results concerning on structure, magnetic properties and magnetization reversal processes in the as-cast Pr8Dy1Fe60Co7Mn6B14Zr1Ti3 alloy in the form of 1 mm plate. The XRD studies revealed coexistence of three phases dominant Pr2(Fe,Co)14B and minor á-Fe and Fe3B. The remanence-to-saturation ratio Jr/Js equaled 0.66 and indicated on existence of strong exchange interactions between hard and soft magnetic phases. The analysis of Mrev vs. Mirr dependences, the pinning mechanism was detected in studied alloy. Keywords: bulk alloys, magnetic properties, magnetization reversal processes