This paper presents a study on copper production and distribution in Lower Austria's southeastern region during the Late Bronze Age (c. 1350-800 BC), with the focal point being the chemistry and ...isotopic character of artifacts from a small copper mining site at Prigglitz-Gasteil on the Eastern Alps' easternmost fringe. Ores, casting cakes, and select objects from the Late Bronze Age mining site at Prigglitz-Gasteil, Lower-Austria, and within 15 km of its surroundings, were chemically and isotopically analysed using XRF, NAA, and MC-ICPMS. The importance of Prigglitz-Gasteil as a local mining and metal processing center is evaluated based on the produced data, and the distribution and sourcing of copper-producing materials found at the site are discussed. Special attention is paid to the mixing of scrap and source materials early in the metal production process. The most salient discussions focus on the variability of the chemistry and Pb isotopic ratios of the studied objects, which seem to constitute a multitude of source materials, unlike the pure chalcopyrite-source copper produced from the Prigglitz-Gasteil mine itself. The analytical data suggests that copper alloys were mainly imported from materials originating in the Slovakian Ore Mountains, which were subsequently mixed/recycled with relatively pure locally produced copper. The purity of the copper from Prigglitz-Gasteil was fortuitous in identifying imported copper that contained measurable amounts of Pb and other chemically distinct characteristics. The chaîne opératoire of metal production at the site is mentioned; however, it is clear that additional information on the region's geochemistry is required before any finite conclusions on the ore-to-metal production can be made.
Rapid advancements in science and technology have assured biomaterials and their associated fields towards becoming a multimillion-dollar industry. Biomaterials have been shown as one of the most ...promising materials for biomedical implant development. As such, this article intends to provide a comprehensive review of metal additive manufacturing (metal-AM) processes evolution used in biomedical applications. The most common types of metal-AM methods practised today are Selective Laser Sintering (SLS), Selective Laser Melting (SLM), Direct Metal Laser Sintering (DMLS), Electron Beam Melting (EBM) and Laser Engineered Net Shaping (LENS). The present review also covers the application of these metal-AM systems in Ti-6Al-4V-based implants fabrication. The scientific challenges and critical issues towards improving the biomaterial properties so that they are more notable in the biomedical industry are also discussed.
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In this paper, Yttria-stabilized zirconia reinforced tungsten alloys (W-YSZ) were prepared by liquid phase method combined with powder metallurgy technology, aiming at optimizing the powder quality ...and improving the properties of tungsten alloy. In the process of hydrothermal synthesis, ZrO2 with various crystal structures can be prepared by controlling the ratio of ZrO2 to Y2O3. When the doping mass ratio of ZrO2 and Y2O3 is 4:1, ZrO2 can be stabilized to form cubic phase structure. ZrO2 and excessively doped Y2O3 in the composite powders can refine the particle size of tungsten particles and reduce the degree of agglomeration. Compared with SPS sintered samples, the size of the samples sintered by vertical melting is coarser, but because of the low sintering temperature of SPS, the density is lower, while the density and hardness of the samples sintered by vertical melting are higher. After sintering at high temperature, the zirconia did not undergo crystal transformation, but remained cubic phase. The (110) of W and (002) of YSZ have a semi-coherent relationship, and the mismatch rate is 12% according to calculation, with good interface bonding and no obvious cracks. Due to the doping of YSZ particles, the strength and toughness of the tungsten alloy are enhanced by the combined effect of dispersion strengthening and fine grain strengthening.
•ZrO2 with different crystal structure was prepared by hydrothermal method.•Excessive doping of Y2O3 can not only stabilize zirconia, but also refine the grain.•W-YSZ alloy prepared by liquid phase method has fine particles and uniform distribution.•The addition of YSZ particles increases the strength and toughness of the tungsten alloy.•W (110) and YSZ (002) have a semi-coherent relationship.
The authors researched the physical, metallurgical, and mechanical characteristics of A354 alloy (Al-Si-Mg-Cu) reinforced with 5, 10, and 15 wt% of fly ash metal matrix composites. A baseline alloy ...and three composites were fabricated by a liquid metallurgy route and poured into a permanent mold to obtain cast rods of dimension Φ32 mm × 156 mm. The metallurgical characterization of the developed alloy and metal matrix composites was conducted using energy-dispersive spectroscopy (EDS), field-emission scanning electron microscopy (FESEM), and X-ray diffraction. All the developed composites showed a pore-free nature, but only A354 alloy reinforced with 5 wt% of fly ash (AF5) possessed a homogeneous distribution and perfect bonding of the fly ash with the A354 matrix. Therefore, transmission electron microscopy (TEM) analysis was performed on the sample AF5. All developed alloys and metal matrix composites were subjected to hardness and mechanical property tests. It was observed that the AF5 sample had 170 ± 5.6 HV and tensile strength of 216 ± 2.3 MPa, 18.8% and 24.8% higher than the A354 matrix, but the ductility (6.5 ± 0.43%) was reduced by 23% from the baseline alloy. Finally, the fractography analysis was conducted on all the samples using FESEM to analyze the fracture mode. The fabricated 5 wt% fly ash-based metal matrix composite showed better mechanical performance than other samples. Hence, sample AF5 is suggested for manufacturing components in automotive and structural parts.
This article reviews original work and important new developments in the field of deformation behavior of high manganese face-centered cubic γ-Fe alloys. Owing to their exceptional mechanical ...properties, these alloys, referred to as twinning-induced plasticity, or TWIP, steels, have come to the fore as prime candidate materials for light-weight applications, notably in automotive, shipbuilding, and oil and gas industries. It is established that a superior combination of strength and ductility exhibited by TWIP steels is associated with a specific character of the variation of the dislocation density. The defining feature of TWIP steels is the small magnitude of the intrinsic stacking fault energy. In addition to limiting the dynamic recovery rate, the low stacking fault energy of TWIP steels results in the formation of isolated stacking faults and deformation twins, which reduces the dislocation mean free path. Both effects lead to an increased strain hardening rate. Despite the progress made, there are still considerable differences between the models proposed for the microstructural evolution during the deformation of TWIP steels and the concomitant strain hardening behavior. The review surveys the experimental literature, summarizes the current modeling concepts, and identifies the outstanding issues with TWIP steels that require the attention of the materials science community. Suggestions for the directions of future research on twinning-induced plasticity steels are offered.
•2-TMAT is good organic corrosion inhibitor for carbon steel in 1M HCl.•Polarization and EIS methods are in reasonable agreement.•2-TMAT adsorption is well described by Langmuir isotherm.•XPS ...analyses were used to explain the 2-TMAT mechanism of carbon steel corrosion inhibition.
Corrosion inhibition of carbon steel in normal hydrochloric acid solution at 30°C by new 4-amino-1,2,4-triazole derivative, namely 3,5-bis(2-thienylmethyl)-4-amino-1,2,4-triazole (2-TMAT) has been studied by electrochemical impedance spectroscopy (EIS) and polarization techniques. The experimental results have showed that this organic compound revealed a good corrosion inhibition and that the inhibition efficiency is increased with the inhibitor concentration. Two time constants determined by the charge-transfer and the adsorption of the inhibitor, respectively, can be readily outlined. Potentiodynamic polarization showed that 2-TMAT is a mixed type of inhibitor. The adsorption of 2-TMAT on the carbon steel surface in 1M HCl solution obeyed to the Langmuir isotherm with a very high negative value of the standard Gibbs free energy of adsorption ΔGads° (chemisorption). X-ray photoelectron spectroscopy (XPS) analyses were carried out to establish the mechanism of corrosion inhibition of carbon steel in 1M HCl medium by 3,5-bis(2-thienylmethyl)-4-amino-1,2,4-triazole (2-TMAT).
•Zn doped NiFe alloy was prepared by microwave sintering coupled with Zn as space holder.•The NiFe alloy had a low overpotential of 235 mV at 100 mA cm-2 and a low Tafel slope of 26.1 mV dec-1.•A ...metal (oxy)hydroxide amorphous layer was formed through electrochemical self-reconstruction.•The Zn in the porous NiFe alloy could be dissolved to further improve the specific surface area.•The porous bulk NiFe alloy exhibited superior stability in 1.0 M KOH.
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Oxygen evolution reaction (OER) electrocatalysts play an important role in producing high purity hydrogen fuels in the water splitting reaction. However, developing bulk catalytic electrode with low-cost and efficient activity for OER is still a challenge. In this paper, the porous bulk NiFe alloys with nanosheet structure were fabricated by a facile microwave sintering powder metallurgy method coupled with Zn as space holder. The obtained porous bulk Ni0.75Fe0.25 alloy exhibits the high catalytic activity for OER with a low overpotential of 235 mV at 100 mA cm−2, a small Tafel slope of 26.1 mV dec−1 and superior stability in 1.0 M KOH. In addition, the residual Zn in the porous NiFe alloy can be dissolved to further improve the specific surface area, and a metal (oxy)hydroxide amorphous layer is formed through electrochemical self-reconstruction during the OER process. This Zn-doped porous bulk NiFe catalyst with high OER catalytic performance and outstanding stability can become a promising candidate for commercial water splitting.
This study investigated microstructures and mechanical behavior of a powder metallurgy (PM) Ti–3Al–2Zr–2Mo marine titanium alloy. This PM alloy was prepared by a fast sintering and immediately ...followed hot extrusion of TiH2-based powder compact. Most of the β-phase strips in as-extruded sample were found to become discontinuous via a dehydrogenation reaction of β (H) → α + β + H2 during vacuum annealing. Such annealing rendered this alloy an excellent ultimate tensile strength up to 1080 MPa and a superior elongation to fracture of 14.0%. Further, a common annealing of 920 °C/1 h/AC brought about a lamellar microstructure consisting of coarsened α laths and β-transformed structures. Consequently, the ultimate tensile strength decreased slightly, the elongation decreased to 9.50%. It was noteworthy that the present PM alloy samples exhibited a satisfying combination of superior tensile strength and excellent ductility, which was ascribed to the reasonable oxygen solution and particular lamellar microstructures containing high content of β-transformed structures. Work hardening behavior of the present alloy was investigated, in order to explain the reason for the highly promising mechanical properties.
A commercial Cu-Ni-Si-Cr alloy used as a model material was annealed and then peak-aged. The detailed microstructure and property analyses were performed to determine the correlations between the ...microstructure characteristics and properties. Theoretical calculations, which gave results in good agreement with experimental results, demonstrated that solid-solution scattering and Orowan bypass of precipitate strengthening were the key mechanisms for electrical and mechanical properties, respectively. Furthermore, the effects of composition on the aging behaviors and then electrical and mechanical properties for Cu-Ni-Si series alloys were systematically investigated, showing that both the precipitation extent and mechanical properties improved simultaneously with nominal or effective concentration of the precipitates. Quick estimation on the basis of the present analysis procedure indicates that our work is applicable with high accuracy in real cases.
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