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Ferromanganese nodules represent an industrially untapped source of valuable metals (Mn, Cu, Ni, Ti, Co) but are still just the object of scientific research. In comparison with already utilized rocks, deep-sea deposits are too hard to reach for their full-scale mining to be profitable. Despite of this, current marine engineering allows us to conduct complete exploration and obtain mineral samples. We can already now develop low-cost methods for subsequent processing in anticipation of improved and safer future mining technology. But in what form would be the final product the most applicable? In our study, we reduced the pyro metallurgical pretreatment of raw nodules to two simple steps: roasting and aluminothermic reduction. Then we added a product, manganese-based alloy, to pure aluminum as a new alloying additive. As a reference for experimental alloys, commercial cast AlMn10 master alloy was chosen. The tested samples were prepared using two advanced operations of powder metallurgy: melt-spinning and spark plasma sintering (SPS). Microstructure was described in detail, tribological and selected mechanical properties were measured, and a comparative analysis was conducted. New additive gradually improved properties of alloys to a level close to 3xxx industrial alloys with its increasing percentage in pure aluminum. Measured values did not surpass the referent AlMn10, but there was not recorded any adverse impact associated with the origin of alloying mixture. • New aluminum alloys with the natural additive – reduced deep-sea nodules – modified by rapid solidification. • Extremely fine-grained microstructure with the content of supersaturated matrix regions. • Improved mechanical and tribological properties comparable to commercial alloys of 3xxx group. • Uncommonly high plasticity. [ABSTRACT FROM AUTHOR]

Due to the lack of mineral resources, unconventional raw materials have to be considered. In this work, the use of reduced deep-sea nodules from Clarion-Clippertion Fracture Zone of Pacific Ocean was tested as the natural mixture of alloying elements for aluminum alloys. The nodules were reduced by aluminothermic process without the extraction of individual elements. As the technology for the manufacture of the alloys, the powder metallurgy comprising mechanical alloying and spark plasma sintering was applied. The produced Al-Mn based alloys are characterized by uncommon spherical morphology of Al-Mn intermetallics, which leads to a significant ductility even in the case of high total amount of additives (up to 20 wt%). The wear resistance of the alloys strongly increases with growing amount of the reduced deep-sea nodules. • New aluminum alloys with reduced deep-sea nodules prepared by powder metallurgy. • Unique rounded morphology of intermetallics was obtained. • Improved strength compared with common Al-Mn alloys. • Reduced deep sea nodules improve tribological properties of aluminum. [ABSTRACT FROM AUTHOR]

Abstract: Alloys formed by Ti–Al intermediary phases have low density and very good high-temperature oxidation resistance. Further improvement of high-temperature behaviour can be achieved by a suitable addition of silicon. In this work, Ti–Al–Si alloys containing 20wt.% of aluminium and 10–20wt.% of silicon produced by a reactive sintering technology were tested. Isothermal oxidation tests were carried out at 1000°C in air. The oxidation rate was determined from weight gains caused by oxide formation. Microstructure and phase composition of the oxide layers were studied. Microstructure and hardness changes after various annealing durations were described. [ABSTRACT FROM AUTHOR]

Abstract: Formation of intermediary phases during reactive sintering of Fe–Al–Si powder mixtures at 1100°C was studied in this work. Results show significant difference from already presented results achieved at lower sintering temperatures. Phase composition is closer to the equilibrium phase diagram. Silicon additions up to 10wt.% produce binary Fe–Al phases, further increase of silicon content leads to the formation of FeSi silicide and Al2Fe3Si3 ternary phase. Binary FeSi40 alloy contains FeSi and FeSi2. Porosity is reduced by addition of silicon. The lowest porosity was achieved when 10wt.% of silicon was added. Formation of binary Fe–Al phases is controlled by aluminium diffusion through the layer of intermetallics. In Fe–Al–Si system, the controlling process is the reaction producing ternary intermediary phases. The highest wear resistance was determined in FeAl30Si10 alloy with single-phase FeAl structure. An increase of silicon content reduces the wear resistance although hardness increases. [Copyright &y& Elsevier]

Abstract: In this work, the dependence of microstructure of Fe–Al–Si alloy on conditions of reactive sintering was studied. It was shown that heating rate strongly affects the structure of this alloy. The microstructure consisting of uniformly distributed Al2Fe3Si3 particles in Al2FeSi matrix can only be obtained in this material by rapid heating (over 300Kmin−1). Sufficient reactive sintering temperature to obtain Al2Fe3Si3–Al2FeSi two-phase structure is 750°C. Further increase of the reaction temperature reduces porosity but causes a growth of Al2Fe3Si3 particles. Reactive sintering process is completed during less than 10min in the investigated material. Temperatures over 1050°C produce material composed of FeSi, FeAl and Al2Fe3Si3 phases. However, strongly exothermal reaction of FeSi formation causes melting of the sample. [Copyright &y& Elsevier]

Abstract: In this work, Ti–Al–Si alloys were prepared by reactive sintering. The contents of silicon and aluminium ranged between 0–30wt.% and 0–36wt.%, respectively. Powders of titanium, aluminum, silicon and AlSi30 master alloy prepared by mechanical machining and/or milling were used for sintering. Powders were blended and pressed at room temperature. Sintering was carried out at 900°C for 30min. It was found that it is possible to produce compact materials with the structure corresponding to the as-cast materials when silicon is in the range of 15–20wt.% and aluminium content between 8 and 30wt.%. It was shown that these materials contain two phases—Ti5Si3 and TiAl. The central porosity can be reduced by induction heating. [Copyright &y& Elsevier]

• Ti-Al-Si-X (X˭Co, Cr, Fe, Mo, Nb, Ni) alloys prepared using mechanical alloying and Spark Plasma Sintering. • Alloys have fine-grained and homogeneous microstructure with low porosity. • Alloyed elements increased hardness and compressive strength values. Intermetallic alloys based on Ti-Al-Si system are significant for their excellent high-temperature properties, especially for resistance against oxidation and for achieving good mechanical properties at elevated temperatures. The main problem of these materials is high brittleness at room temperature. In the previous work, selected alloying elements were added into the Ti-Al-Si alloys prepared by reactive sintering, but the properties did not meet the requirements for subsequent use in the automotive or aerospace industry, since the materials had a very porous microstructure. Here, the addition of cobalt, chromium, iron, molybdenum, niobium and nickel into the TiAl15Si15 alloy prepared by mechanical alloying and Spark Plasma Sintering is tested and it is expected to improve the mechanical and high-temperature properties. In this paper, the Ti-Al-Si alloys have been assessed on basis of microstructure, phase composition, mechanical and tribological properties, such as hardness, fracture toughness and compressive strength. Cyclic oxidation tests were performed for 400 h at the temperatures of 800 and 1000 °C. The cyclic oxidation tests simulate industrial processes, where the material is alternately exposed to elevated temperature and subsequent cooling (eg, engine components). From the viewpoint of most of the tested properties, alloying by niobium seems to be the most promising. [ABSTRACT FROM AUTHOR]

Only differential thermal analysis at low heating rates or mathematical modelling have been used to determine Fe–Al phase formation reactions up to this day. In this work, Self-propagating High-temperature Synthesis high-speed reaction was analysed during extremely high heating rates using scanning electron microscope with energy dispersive spectroscopy and X-ray diffraction in this work. Samples, whose chemical composition corresponded to FeAl phase, were sintered at heating rate of 300 °C/min, the highest heating rate applied so far. The course of heating was observed by optical pyrometer with sampling rate of 0.02 s. Pre-combustion peak (diffusion stage) was identified in the alloy prior steep combustion peak corresponding to SHS reaction itself. Accordingly to the temperature development, a FeAl phase formed initially allowing to react with aluminium and forming Fe 2 Al 5 phase. Furthermore, the later mentioned phase partially reacted with aluminium resulting in a presence of metastable FeAl 3 phase. Resulted microstructure was composed of only FeAl phase. This is completely reverse order of phase formation as was presented in previous studies focusing on lower heating rates where Fe 2 Al 5 formed first during diffusion stage followed by the formation of FeAl at SHS reaction. [ABSTRACT FROM AUTHOR]

Abstract: Positron annihilation spectroscopy was employed for the microstructure characterization of rapidly solidified Al–3wt.% Cr–3wt.% Fe–0.8wt.% Ce alloy prepared by melt spinning. Results of the positron annihilation study are analyzed within the diffusion trapping model and compared with results of X-ray diffraction, transmission electron microscopy and microhardness measurements. A good consistency among all experimental techniques was obtained. The rapidly solidified alloy exhibits ultra fine grained structure, consisting of cells separated by dislocation walls. Annealed samples showed no significant changes in structure up to 400°C which proves good thermal stability of ultra fine grained structure. Exposure of the sample to temperature of 500°C caused significant changes in the material. [ABSTRACT FROM AUTHOR]

Using the recently developed method based on a combination of DFT plane wave code applied to extract the crystal field parameters and a local atomic like Hamiltonian involving electron-electron, spin-orbit and Zeeman terms we calculated the energy levels of ground and excited multiplets of Yb3+ and Er3+ ions hosted in ytterbium and yttrium aluminum garnet (YbAG and YAG) including their crystal and magnetic field splitting. The obtained energy levels and derived magnetic properties are compared with the experimental data from magnetometry, photoluminiscence and near-infrared spectroscopy. Image 1 • Optical and magnetic properties of Er3+ doped ytterbium-aluminium garnet were assessed using a combined theoretical and experimental approach. • Crystal field parameters for Er3+ and Yb3+ were calculated using DFT method and further used to obtain the ground and excited state energies. • Optical and magnetic properties derived from the calculated energies are in nice agreement with the experimental data. [ABSTRACT FROM AUTHOR]