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The heating of high-Ni cathode materials under low O2 partial pressures has generally been considered undesirable. Contrary to this general understanding, this study reports the postheating of LiNi...

Electropulsing treatment was imposed on SUS303 free-cutting steels to analyze the evolution of MnS inclusions. SUS303 steels were treated in argon atmosphere under various conditions: before the formation of MnS inclusions (1773 K), at the beginning of the formation of MnS inclusions (1678 K), and after the formation and growth of MnS inclusions (1583 K). The results show that the sizes of globular MnS inclusions decrease with an increase of current density when the electropulsing treatment is treated in the melting stage. Meanwhile, electropulsing treatment restrains the growth of inclusions due to the different conductivities between the molten steel and MnS inclusions when electropulsing treatment is treated in the solidification process. However, the number of fine rodlike MnS inclusions increases with the increase of current density in the samples treated in the inclusion nucleation stage and solidification stage because the reduction in chemical potential produced by electropulsing treatment will require less undercooling. Experimental data demonstrate that the application of electropulsing treatment is a fantastic new method to control the morphology and size of MnS inclusions in the melting stage.

In this study, phase formation, the microstructure and the thermal properties of an Al-Mg alloy solidified at high temperature in the argon atmosphere were investigated. The maximum formation of a single-phase Al-Mg alloy was determined by the ratio of the primary aluminum and magnesium components Al – 50 at.% Mg and argon gas flow at a temperature of 750 oC. After solidification at pressures of 1 MPa and 2 MPa, the main phases are the β and γ phases of Al-Mg alloy, in equilibrium condition. The thermal properties of the Al-Mg alloy were studied using DTA-TG (Tmelting = 458.4 oC, Тoxidation= 568.4 and 616.9 oC oxidation of pure Mg and pure Al, respectively).

To develop an effective method for removing sulfur from spent refining slag at high temperature, the slag was treated in argon atmosphere using desulfurization ash as desulfurization reagent. Experimental results revealed that at 1773 K, molar ratio of CaS to CaSO4 + CaSO3 of 3:1, and reaction time of 2 hours, sulfur removal efficiency reached a maximum of 67.9 pct. The optimal ratio indicates the reaction of CaS and CaSO4 + CaSO3 to generate S2 may predominante during processing.

The effects of milling time on the structural and morphological features of Si-based refractory compounds (SBRC) derived from selected agro-wastes (bamboo leaves- BL and coconut shell-CS) are reported. The processing of the SBRC was done using the controlled environment of a conventional furnace at a heating rate of 10°/min between 900 and 1650 °C. The SBRC was then placed in 250 ml vial containing zirconia balls as grinding media of 8 mm in diameter to mill in an argon atmosphere (ultra-pure with 99.98% wt

The Guizhou high-sulfur coal and its demineralized coal were rapidly pyrolyzed in a drop tube furnace under an argon atmosphere at the high temperatures ranging from 700°C to 1200°C. The effects of...

An investigation was conducted to evaluate the stress corrosion cracking resistance of copper based alloys. Cu, Ni, Sn of appropriate weight percentage were melted in a graphite crucible in an electric furnace under the argon atmosphere. The obtained specimens were solutionised and aged as per standards. The heat treated samples were subjected for microstructural evaluation and stress corrosion cracking test as per ASTM standard. In the microstructural analysis it was observed that the dendritic structure was completely vanished when the specimen was subjected to solutionising and aging. The stress corrosion cracking (SCC) was predominant in the regular bronze due to the formation of oxide layers according to the passive film rupture theory. But in the case of spinodal alloys only internal cracks were observed. These observed cracks were due to the pits and burrs present in the alloy

The Pidgeon process is the main extraction method of magnesium, but its continuous production cannot be achieved due to the switch between vacuum and atmospheric pressure. Therefore, it is vital to realize continuous extraction of magnesium under atmospheric pressure. In this paper, the process of extracting magnesium from prefabricated pellets in flowing argon was proposed. The isothermal kinetic analysis of the reduction process was carried out. The results showed that the reduction process was controlled by diffusion process in 1 h, and the apparent activation energy of extracting magnesium from prefabricated pellets in flowing argon was 218.75 kJ/mol. Then the influence of experimental factors on the reduction rate was explored, including briquetting pressure, carrier gas flow rate, ferrosilicon content, reaction temperature and time. Through analysis and calculation, it was concluded that the main control step of diffusion process was silicon diffusion.

Aluminum is the key ingredient in low-density steels. It leads to the formation of δ-ferrite in a large fraction. In order to study the influence, two different experimental approaches were devised. In a first of its kind, the sample was arc melted in an argon atmosphere. Later, the same alloy composition was ball milled and sintered at 1000 °C by avoiding liquid to δ-ferrite in the system. In the current study, the comparative analysis led by DICTRA simulation indicates that kappa (κ) carbide has difficulty forming in the present alloy system when δ-ferrite is already available, particularly during solidification casting.

In this paper, four Nb-xTi-16Si–3Cr–3Al-2Hf-yZr (x + y = 20) alloys prepared by arc-melting furnace with non-consumable tungsten electrode, which was heat-treated at 1400 °C/50 h in argon atmosphere. The microstructures of the as-cast alloys and the heat-treated alloys were observed, and the room temperature fracture toughness and the hardness were tested. The results indicated that with the increase of Zr content, γ-Nb5Si3 phase appeared in as-cast alloys with an increasing volume fraction. After heat treated, the microstructures of the alloys were finer, and the transformation from γ-Nb5Si3to α-Nb5Si3 occurred. In addition, the room temperature fracture toughness and hardness of the heat-treated alloys are higher than those of as-cast alloys. For heat-treated alloys, the room temperature fracture toughness presented a slight downtrend followed by an uptrend with increase proportion of Zr, however the hardness was being improved. By contrast, for as-cast alloys the toughness and the hardness decreased.

The wetting of 12Cr18Ni10Ti and EK-173 reactor steels by an eutectic melt of PbBi with lithium under conditions of a vacuum and an argon atmosphere is studied in a wide range of temperatures. A tendency is observed toward the improved wetting of 12Cr18Ni10Ti steel with a higher lithium content in a eutectic melt of PbBi. It is found that an eutectic PbBi alloy with 20.86 at % of Li content tends to improve the wetting process under the conditions of a vacuum and an argon environment.

In this study, (Ni70Si30)100−x Fe x (x = 0, 5, 10) alloys were synthesized through the arc-melting technique under a vacuum/argon atmosphere. The microstructural properties and microhardness of the nickel (Ni)–silicon (Si)–iron (Fe) alloys were characterized. These alloys were investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and Vickers microhardness measurement. The XRD results showed that all alloys have some intermetallic phases such as Ni2Si, Fe2Si, Ni74Si26 and Fe3Ni. These phases were confirmed by SEM-energy-dispersive X-ray spectroscopy analyses. From OM images, planar and dendritic growths were observed. The obtained phases affected positively the microstructures of the alloys. Thus, the microhardness values of the alloys improved and were determined to be in the range 866–1024 HV. Moreover, these microhardness values revealed that the iron content in the the nickel–silicon alloy system was a very significant factor to be determined increasing and decreasing of the the microhardness values the alloys.

In this study, hot corrosion behaviours of Haynes 282 (H282), Nimonic 90 (N90), and Haynes HR160 (HR160) in LiCl-Li2O molten salt were investigated at 650 °C under argon atmosphere. The corrosion rate was in the order of H282

Present study investigates microstructural stability and mechanical properties of spark plasma sintered Fe-Cr-Nb alloys for its nuclear first wall reactor application. The nanostructured alloys were prepared by mechanical alloying (MA) for 25 h in argon atmosphere (purity

Presently, the majority of titanium powder metallurgy components produced are sintered under high vacuum due to the associated benefits of the vacuum atmosphere. However, high-vacuum sintering is a batch process, which limits daily production. A higher daily part production is achievable via a continuous sintering process, which uses argon gas to shield the part from air contamination. To date, there has been limited work published on argon gas sintering of titanium in short durations. This study investigated the properties of thin high green density titanium strips, which were sintered at the temperatures of 1100 °C, 1200 °C and 1300 °C for a duration of 30 min, 60 min and 90 min in argon. The strips were produced by rolling of −45 µm near ASTM (American Society for Testing and Materials) grade 3 hydride–dehydride commercially pure titanium powder. The density, hardness, tensile properties and microstructure of the sintered strips were assessed. It was found that near-full densities, between 96 and 99%, are attainable after 30–90 min of sintering. The optimum sintering temperature range was found to be 1100–1200 °C, as this produced the highest elongation of 4–5.5%. Sintering at 1300 °C resulted in lower elongation due to higher contaminant pick-up.

Four metallurgical cokes were heat treated at 1250 °C to 1550 °C in argon atmosphere. The influence of heat treatment on the microstructure of metallurgical cokes was characterized using X-ray diffraction and Raman spectroscopy. Wettability experiments were carried out using the sessile drop technique. The wettability of cokes with liquid Fe-85wt%Mn at 1550 °C was measured as a function of time. The effect of coke ash content, microstructure, porosity and roughness on the wettability was investigated. In the process of heat treatment, the microstructure of the metallurgical cokes transformed toward the graphitic structure. The Raman spectra showed variations reflecting their temperature histories. Area fraction of G peak increased as the annealing temperature increased and intensity ratios of D to G band decreased with temperature. All the four coke samples showed non-wetting behavior with Fe-85wt%Mn while graphite showed wetting behavior. Coke E with the highest roughness and porosity showed the lowest wettability compared to other cokes. Crystallite size of the coke samples did not seem to have any significant effect on the wettability. © 2020 The Author(s). Published with license by Taylor and Francis Group, LLC This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4. 0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.

In this study, Al matrix composites consisting of different amounts of Zn, Cu, and Mg were produced using the powder metallurgy technique. In the alloying, powders were ball milled for 120 min via mechanical alloying. After alloying process, the powders were pressed at 800 MPa at room temperature. Sintering (2 h at 600 °C in argon atmosphere), solution treatment (2 h at 480 °C), and aging processes (3, 6, 9, and 12 h, respectively, at 120 °C) were applied to the samples. The hardness and tribo-metallurgy properties of the products were investigated. After sintering, the hardness values of the three alloys were close to each other; however, the solution treatment after sintering caused the hardness values to increase significantly. It was determined that the Al-2Zn-5Cu-4Mg alloy had the highest hardness increase with the 6-h aging heat treatment. The wear resistance of the materials in all the compositions had increased. The highest wear resistance and lowest friction coefficient were obtained for the Al-2Zn-5Cu-4Mg alloy with the 6-h aging heat treatment. © 2020 Authors. Published by association for ETRAN Society.

An approach for tape casting and sintering of Li7La3Zr1.75Nb0.25Al0.1O12 (LLZNbO) sheets suitable for use in solid-state battery development is described. The use of Li3BO3 as a sintering aid in both pellet and cast tape samples is examined. We find the optimal Li3BO3 content for ionic conductivity in pellets is between 1 and 2 wt% Li3BO3, much less than in prior reports. At this level, ionic conductivity is ~2.5 × 10−4 S cm−1 after sintering in an argon atmosphere at 1000 °C for 6 h. 150–175 micron thick LLZNbO + 0.5% Li3BO3 tapes sintered at 1000 °C for 6 h exhibit ionic conductivity values of 2–3 × 10−4 S cm−1.

Fe–Ni–Cr-based super-high-strength maraging stainless steels were generally realized by multiple-element alloying under a given heat treatment processing. A series of alloy compositions were designed with a uniform cluster formula of [Ni16Fe192](Cr32(Ni16–x–y–z–m–nMoxTiyNbzAlmVn)) (at.%) that was developed out of a unique alloy design tool, a cluster-plus-glue-atom model. Alloy rods with a diameter of 6 mm were prepared by copper-mold suction-cast processing under the argon atmosphere. These alloy samples were solid-solutioned at 1273 K for 1 h, followed by water-quenching, and then aged at 783 K for 3 h. The effect of the valence electron concentration, characterized with the number of valence electrons per unit cluster (VE/uc) formula of 16 atoms, on microhardness of these designed maraging stainless steels at both solid-solutioned and aged states was investigated. The relationship between alloy compositions and microhardness in maraging stainless steels was firstly established by the random forest (RF, a kind of machine learning methods) based on the experimental results. It was found that not only the microhardness of any given composition alloy within the frame of cluster formula, but also the alloy composition with a maximum microhardness for any given VE/uc, could be predicted in good agreement with the guidance of the relationship by RF. The contributions of minor-alloying elements to the microhardness of the aged alloys were also discussed.

Kaolins are used in a multiplicity of industries because of unique physical and chemical properties. Relationships between thermal and radioactivity properties are discussed in its application as a building material. Super-fine kaolin powder with particle sizes about 30 mu m was analyzed. Simultaneous TGA/DTA analysis was performed on powder samples at various heating rates in an argon atmosphere. Based on investigated thermal properties, it was concluded that dehydroxylation process can vary depending on the characteristics of starting material. The maximum degree of the dehydroxylation (D (T)) was obtained at the lowest rate of heating (D (T) = 60.79% for 10 A degrees C min(-1)). With an increase in the heating rate, decline in D (T) value was observed. Based on comprehensive testing, it was identified that the degree of dehydroxylation does not drop below 50%. It was concluded that appointed experimental conditions seem sufficient admissible for obtaining degree of dehydroxylation (D (T)) higher than 50%. In order to safe use of kaolin as a building material from the standpoint of radiological safety, content of natural radionuclides was determined by gamma spectrometry.

The present study aims to fabricate fullerene (C60) reinforced magnesium matrix composite via semi powder metallurgy in hot press system under high purity argon atmosphere. Improvement of wear resi...

The effect of the chromium concentration on the magnetic properties of Fe–Cr precursors for hard-magnetic Fe–Cr–Co materials is studied. Nitrogen used as a sintering atmosphere and a long annealing time enhance are found to increase the coercive force Hc of the materials. The phase formation in Fe–30% Cr alloys is traced during heat treatment in nitrogen and argon atmosphere using thermal analysis.

ODS ferritic steels were produced by mechanical alloying (MA) in either attritor or planetary ball mills under argon atmosphere and hot extrusion. Milling in argon with controlling excess oxygen (Ex.O) and nitrogen was effective to reduce the particle size of MA powders. Coarse Al2O3 particles and fine AlN precipitates were found to be formed in an Al added steel when the Ex.O and nitrogen concentrations are increased. Lowering the Ex.O and nitrogen concentrations in ODS ferritic steels acted as a key parameter for enhancing their impact properties.

The effect of two different annealing processes on the microstructure and barrier-forming ability of Cu-Zr alloy films has been investigated. Cu-Zr alloy films were deposited directly onto SiO2/Si substrates via direct current magnetron sputtering and subsequently annealed by the vacuum annealing process (VAP) or rapid annealing process under argon atmosphere at temperatures 350°C, 450°C, and 550°C. Then, the microstructure, interface characteristics, and electrical properties of the samples were measured. After annealing, the samples showed a preferential (111) crystal orientation, independent of the annealing process. After two annealing methods, Zr aggregated at the Cu-Zr/SiO2 interface and no serious interdiffusion occurred between Cu and Si. The leakage current measurements revealed that the samples annealed by VAP show a higher reliability. According to the results, the vacuum annealing has better barrier performance than the rapid annealing when used for the fabrication of Cu-based interconnects.

The objective of the present work is to characterize the wear behavior of a cryogenically treated low-carbon AISI 420 martensitic stainless steel, by means of ball-on-disk tribological tests. Wear tests were performed under a range of applied normal loads and in two different environments, namely a petrolatum bath and an argon atmosphere. Wear tracks were analyzed by both optical and scanning electron microscopy (SEM) and Raman spectroscopy to evaluate wear volume, track geometry, surface features and the tribolayers generated after testing. This paper is an extension of the work originally reported in the VIII Iberian Conference of Tribology [G. Prieto, W.R. Tuckart, VIII Iber. Conf. Tribol., Cartagena, España, 2015: pp. 68?75].In this study, it has been experimentally demonstrated that cryogenically treated specimens showed a wear resistance improvement ranging from 35 to 90% compared to conventionally treated ones. Fil: Prieto, Germán. Universidad Nacional del Sur. Departamento de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Tuckart, Walter Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; Argentina

Al 2 O 3 -SiC composite powders were successfully fabricated from coal ash by carbothermal reduction reaction (CRR) method in argon atmosphere. The effects of raw materials ratio, reaction temperature, La 2 O 3 and Sm 2 O 3 additions on the synthesis process were investigated in detail. Phase compositions and microstructures of Al 2 O 3 -SiC composite powders were characterized by XRD and SEM. Proper processing parameters and rare earths addition amounts were determined, and the formation process of Al 2 O 3 -SiC powders was also discussed.

The isothermal and cyclic corrosion behavior of yttria (Y2O3)-stabilized zirconia (ZrO2) in a LiCl-Li2O molten salt were investigated at 650 °C in an argon atmosphere. During isothermal and cyclic ...

Formation of the Ni2MnSn Heusler alloy by solid state reaction from elemental powders was investigated. The solid state reaction was conducted in a planetary ball mill under argon atmosphere up to 28 h of milling. During the milling, after selected intervals samples were collected and studied by X-ray diffraction to record phase changes. After 16 h of milling a two phase mixture (Ni2MnSn with B2 structure and NiMnSn with C1b structure) was found. Further, the thermal stability of the samples was investigated, and phase precipitation was found. The formed phases are ordered Full Heusler (L21) and Ni3Sn2. The formation temperature and their amount evolution versus temperature and milling time is discussed. An inversion of the formation temperature was found for the L21 and Ni3Sn2 phase, during the DSC study, in relation with the milling time. For the B2 compound a stability range on temperature was identified (from 25 to 300 °C), as well as for the L21 and Ni3Sn2 phases (from 400 to 600 °C) in the case of 28 h milled sample. The milled and annealed sample exhibit nanocrystalline state, formation mechanism under temperature was concluded to be by precipitation.

Strain controlled thermomechanical fatigue (TMF) behavior of Cu-Cr-Zr-Ti alloy was studied in the temperature range of 375–525 °C in high purity argon atmosphere under both in-phase (IP) and out-of-phase (OP) loading. In the case of OP TMF tests, the material exhibited continuous hardening without any saturation of stress. On the other hand, it showed cyclic hardening for the first few cycles followed by saturation of stress in IP TMF tests. The material exhibited superior lives under OP TMF loading compared to that under IP TMF loading especially at lower strain amplitudes. This may be attributed to the fact that the material experienced peak tensile stress at lower temperatures in OP TMF tests, where the resistance to crack initiation is expected to be higher. Microstructural observations and fractographic studies indicated mixed mode of fracture involving Intergranular facets and transgranular cracking in both IP and OP TMF tests.

Objectives: This study evaluated the effect of argon atmosphere compared with vacuum during porcelain firing on the fracture strength of crowns made of porcelain and electron beam melted (E...

The marginal adaptation of prosthetic crowns is still a significant clinical problem.The purpose of this in vitro study was to evaluate the marginal deficiency and misfit of Ni-Cr alloys with and without beryllium under different casting conditions.Four casting conditions were selected: flame-torch, induction/argon, induction/vacuum, and induction/air; and 2 alloys were used, Ni-Cr-Be and Ni-Cr. For each group, 10 metal specimens were prepared. Silicone indirect impressions and analysis of the degree of rounding were used to evaluate the marginal deficiencies of metal copings, and a standardized device for the setting pressure associated with optical microscopy was used to analyze the marginal misfit. Results were evaluated with 2-way ANOVA (α=.05), followed by the Tukey honest significant difference post hoc test, and the Pearson correlation test (α=.05).Alloy (P.001) and casting technique (P.001) were shown to affect marginal deficiencies. The Ni-Cr cast using the torch technique showed the highest marginal deficiency, and the Ni-Cr-Be cast in a controlled argon atmosphere showed the lowest (P.001). Alloy (P=.472) and casting techniques (P=.206) did not affect the marginal misfit, but significant differences were found in the interaction (P=.001); the lowest misfit was achieved using the Ni-Cr-Be, and the highest misfit occurred with the molten Ni-Cr, using the cast torch technique. No correlation was found between deficiency and marginal misfit (r=.04, P=.69).The interactions demonstrated that the alloy containing beryllium that was cast in an argon atmosphere led to reduced marginal deficiency. Improved marginal adaptation can be achieved for the same alloy by using the torch technique.

Cr (0.2 at.%) and Nd (0.8 at.%) co-doped Lu3Al5O12 ceramics were fabricated with MgO as the sintering additive. The addition of a small amount of MgO can affect the grain boundary mobility and influence the number and location of micropores in ceramics during the sintering process. The results show that when the MgO content is 0.02 wt.%, high-transparency Cr,Nd:LuAG ceramics can be obtained by vacuum sintering at 1670 °C for 5 h followed by hot isostatic pressing (HIP) post-sintering at 1750 °C in an argon atmosphere (P = 200 MPa) for 5 h. The optimum in-line transmittance of the HIPed Cr,Nd:LuAG ceramics (3 mm thick) is 83.5% at a wavelength of 840 nm and 84.0% at 710 nm.

Recently, Ni-free shape memory Ti-based alloys (composed of the biocompatible β-stabilizing elements such as Ta and Nb) are extensively studied. In this work, new Ni-free Ti-17Nb-6Ta is presented as a candidate for shape memory alloys with high biocompatibility. This alloy produced using arc-melting in argon atmosphere, followed by solution annealing at 900° C for 30 min. β-phase is the predominant phase beside α” martensite phase. Stress induced martensitic transformation is observed after cold rolling and during bending tests as measured by XRD. The hardness of the bended wire in the solution treated condition was around 330HV. While the cold rolled wire hardness before bending was 300 HV. The superelasticity and shape memory effect was investigated through bending tests of alloy wires. The cold rolled wire showed higher superelasticity than shape memory effect. But superelasticity and the shape memory effect were almost similar with the solution treated wire. Also, the total spring back in cold rolled wire is higher compared with solution treated wire.

Evolution of hydrogen during the plastic state is a key parameter in coke making for the production of quality coke. Based on this phenomenon, a new devolatilization method has been developed for accessing the coking property of coals using the evolution of H2 during thermogravimetric–mass spectrometer (TG-MS) analysis. Four coals having different coking potentials, commonly used in steel industries, were considered. The investigation was performed at temperatures up to 1100 °C in an argon atmosphere under a constant heating rate of 3 °C/min to simulate the coking environment. Nonisothermal kinetics is considered as a good indication of different reaction regimes during pyrolysis, which is generally done through TGA alone. In this study evolution of H2 is used to develop nonisothermal kinetics through a new quantification approach. Finally, a definite and more generic correlation was established, based on H2 enrichment in volatiles around specific temperature zones, for measuring the exact coking behavior...

An investigation was carried out to understand the effects of Co, Ti and Si additions to the AlCuNiFe entropy alloys on the microstructure, hardness and wear properties. The entropy alloy samples were prepared by an arc melting process under an argon atmosphere. Hardness and wear rate were measured using a microhardness tester and a Pin-On-Disc wear tester respectively. EDAX and XRD analyses were also carried out. The entropy alloys showed a high hardness and a low wear rate compared to several conventional alloys. Si and Ti contribute significantly to the increase in the hardness when compared to Co in the AlCuNiFe system. Si tends to form a separate phase due to the effect of entropy of mixing. The results of this study are comparable to those of previous works.

Hexagonal plate-like Al 4 Si 2 C 5 particles were synthesized for the first time via a carbothermal reduction process with controlled heating temperature and raw materials ratio, and their oxidation behavior was investigated. Al 4 O 4 C, Al 2 OC, SiC and Al 4 SiC 4 formed as intermediate products when the batch mixture was heated in argon atmosphere, and Al 4 Si 2 C 5 then formed at above 1800 °C. Possible reaction mechanisms responsible for the formation of this ternary carbide were discussed based on the reactions at the initial and later stages of the carbothermal reduction process. Al 4 Si 2 C 5 added to the Al 2 O 3 –C refractory initially reacts with CO to form Al 2 O 3 , SiO 2 and C. After the reaction, Al 2 O 3 react with SiO 2 to form mullite on the surfaces of the refractories, which inhibit the oxidation of the refractories.

Cold rolling can significantly increase hydrogen storage properties of Mg and its alloys. Therefore in this paper, two important cold rolling processing parameters were investigated: the amount of passes and the roll rotation frequency, which directly influence particle and crystallite sizes and thus the interfaces for hydrogenation/dehydrogenation. Extensive cold rolling was conducted with MgH2 powder as starting material under an argon atmosphere to avoid contamination. The results indicate that the cold rolled MgH2 was free from oxides even after 50 cold rolling passes. Additionally, considerable improvements in the hydrogen storage properties were achieved with higher amounts of cold rolling passes. A similar effect could also be found for higher roll rotating frequency. This beneficial outcome originated from three important aspects: the decrease of the crystallite size reaching 88% reduction after 50 passes and 82% after 35 passes with rotating frequency of 50 rpm, the refinement of particle size, and a change in the morphology of the initial MgH2 powder from granules to flakes, and ultimately to small particles.

The isothermal hot pressing (IHP) of skimmed aluminium dross, considered in this study, was performed under laboratory conditions using a cylindrical pressing model made from high-temperature stainless steel. The pressing model was inserted into an electrical furnace with a protective argon atmosphere. The temperature of the pressing was within the interval 650–900 °C, while the applied pressure varied between 5 and 50 bars. The laboratory results showed that when using IHP it is possible to reduce the remaining aluminium content in “pressed dross skulls” below 10%.

Various V-Ta-4Cr-4Ti quaternary alloys containing different amounts of Ta were investigated to determine the effect of Ta concentration on their tensile properties. Six button-shaped ingots of V-xTa-4Cr-4Ti alloys (x = 4, 8, 15, 22, 24, and 35 wt.%) were fabricated on a laboratory scale by using non-consumable arc-melting in argon atmosphere. The sheet specimens for all the V-Ta-4Cr-4Ti alloys examined herein were obtained by cold-rolling; hot-rolling or intermediate annealing was not required. Although the examined alloys were fabricated on a laboratory scale, the high-Ta alloys, unlike the high-Cr alloys, did not experience crack formation in the cold rolling process. It is possible that V-4Cr-4Ti alloys adopt large amount of Ta and its strengthening effect without negative impact on rolling fabricability. Tensile strength tended to increase with increasing Ta content at both room temperature and high temperatures of 973 K and 1073 K, which can be attributed to the solid solution strengthening by Ta. Thus, addition of Ta to V-4Cr-4Ti alloys can improve their strength without decreasing their rolling fabricabilities. However, an alloy containing excess Ta (V-35Ta-4Cr-4Ti) showed a loss of ductility and a brittle fracture mode due to the formation of a large amount of friable Laves phase. Therefore, it is necessary to limit the amount of Ta to prevent the formation of the Laves phase.

A novel simple method is presented to synthesize high-purity Ti2SC powder using Ti/C/S and Ti/C/TiS2 systems by microwave hybrid heating at different temperatures in argon atmosphere. It was confirmed that the synthesis temperature is strongly dependent on the starting composition. For Ti/C/S system, Ti2SC with small amounts of TiS and TiC was synthesized at 1200 °C. For Ti/C/TiS2 system, high-purity Ti2SC was synthesized at 800 °C and above. The synthesis of Ti2SC powder at low temperature was attributed to the combination of microwave effect by microwave hybrid heating and the introduction of TiS2 as sulfur source. Scanning electron microscopy (SEM) analysis indicated that the layered structure of Ti2SC particles is perfectly formed at 1100 °C, and the crystal particle size approaches to homogeneity which is about 2–5 μm. It was presumed that the formation mechanism of Ti/C/TiS2 system is that TiS2 firstly reacts with Ti to form Ti–S intermetallics, then Ti–S intermetallics reacts with un-reacted Ti and graphite to produce Ti2SC.

The effect of mechanical activation on the synthesis temperature decreasing of silicon carbide was investigated and a kinetic model of a carbothermic reduction of silicon carbide was obtained. Silicon carbide was synthesized using silica activated in a planetary mill at different times up to 40 h under an argon atmosphere. Structural changes due to the milling and the reduction of the activated silica were studied by the X-Ray diffraction (XRD) method and non-isothermal TGA with a heating rate of 10∘C min−1 respectively. The kinetic model obtained by the fitting technique for an unmilled sample was found to be chemically controlled of the second order with E = 138.92 Kcal.mol−1 and A =3.92×1015 s−1. For the sample milled up to 20 h, according to the Avrami-Erofeev3 equation; A = 1465633 s−1 and E = 66.71 Kcal.mol−1.

Results from systematic experimental studies of the temperature dependences of the surface wetting of a number of EK-173, 12Cr18Ni9Тi, and 12Cr18Ni10Тi structural steels using liquid lead, bismuth, and a eutectic melt of PbBi with lithium under vacuum and/or an argon protective atmosphere. Critical wetting temperatures are found on the polytherms of the wetting of EK-173, 12Cr18Ni9Тi, and 12Cr18Ni10Тi steels using lead, bismuth, and a eutectic melt of PbBi under vacuum. It is shown that steel of EK-173 grade is more stable than 12Cr18Ni9Тi structural steel when in contact with a eutectic melt of PbBi at higher temperatures. Steel wetting is considerably higher under vacuum than in a protective argon atmosphere. Study of the wetting of 12Cr18Ni10Тi steel using liquid alloys of (PbBi)eut with lithium revealed a tendency toward improved wetting of steel with higher lithium content in a eutectic melt of PbBi.

The nonlubricated sliding wear behavior of nano-yttria-dispersed and yttria-free duplex and ferritic stainless steel against a diamond tip was studied. The stainless steel samples were fabricated by a conventional powder metallurgy route in which nano-yttria-dispersed and yttria-free duplex and ferritic stainless steel powders were cold compacted and then conventionally sintered at either 1000, 1200, or 1400°C in an argon atmosphere. For comparison, another set of samples was sintered at 1000°C in a nitrogen atmosphere. The wear behavior of sintered stainless steel samples against a diamond indenter was investigated using a pin-on-disc apparatus at 10 and 20 N loads and at a constant speed of 0.0041 m/s. It is proposed that yttria-dispersed stainless steels showed higher wear resistance compared to yttria-free stainless steel due to their improved hardness and density. Stainless steel sintered in a nitrogen atmosphere exhibited better wear resistance than those sintered in an argon atmosphere due ...

In the course of recent years, several experiments were performed at MTA EK (Centre for Energy Research, Hungarian Academy of Sciences) on the isothermal high-temperature oxidation of the improved Russian cladding alloy E110G in steam/argon atmosphere. Using these data and designing additional supporting experiments, the oxidation kinetics of the E110G alloy was investigated in a wide temperature range, between 600 °C and 1200 °C. For short durations (below 500 s) or high temperatures (above 1065 °C) the oxidation kinetics was found to follow a square-root-of-time dependence, while for longer durations and in the intermediate temperature range (800–1000 °C) it was found to approach a cube-root-of-time dependence rather than a square-root one. Based on the results a new best-estimate and a conservative oxidation kinetics model were created.

From the creep rupture data for the reduced activation ferritic/martensitic steel F82H, the ratio between the load in the small punch (SP) creep test and the stress in the standard creep test is estimated to be 2.1 in an argon atmosphere and 2.3 in a vacuum. However, the reasons for the difference between the values of stress conversion coefficients and the physical meaning of these values have not been clarified. In this study, stress analyses of SP creep specimens were carried out for F82H by using finite element analysis to clarify the physical meaning of the stress conversion coefficient. The friction coefficient between the ball and specimen affected the SP creep properties, and an increase in the friction coefficient resulted in an increase in the rupture time. The applied load (F) and the averaged equivalent stress in the steady state (σs) correlated linearly, and the increasing friction coefficient tended to decrease σs. It was possible to replicate the test results obtained in the argon atmosphere with a friction coefficient of 0.39 and the results obtained in the vacuum with a friction coefficient of 1.3. It was also found that the SP creep test results, which were determined by σs, agree well with the standard creep test results.

In a preliminary study carried out for evaluating creep properties with the small punch (SP) creep testing method, creep tests were performed using reduced activation ferritic/martensitic steel (RAFMs) F82H specimens both in an argon atmosphere and in vacuum (less than 10−3 Pa). The results showed that the rupture time was approximately 2.5 times longer in the argon atmosphere compared to that in the vacuum. Changes in the deflection rate with the deflection and time and changes in the minimum creep deflection rate with the rupture time were almost independent of the test atmosphere, although the minimum creep deflection rate decreased as the rupture time increased. After comparing the SP creep test results, which were sorted by using the Larson-Miller parameter, and the standard creep test results, the ratio (F/σ) between the load (F) in the SP creep test and the stress (σ) in the standard creep test was determined to be 2.1 and 2.3 for the argon atmosphere and vacuum, respectively. Consequently, it was found that the ratio, namely, the load/stress conversion coefficient, depended on the test atmosphere. This result implied that the stress and/or strain distribution on the SP specimen varied with the type of atmosphere. This change with the test atmosphere seemed to be closely associated with changes in the friction between the specimen and the ball.

La1.8Ti0.2MgNi9–x Co x (x = 0, 0.1, 0.3, 0.5) alloys were prepared by magnetic levitation melting under argon atmosphere. The effects of Co substitution on the phase structure and the hydrogen storage properties of the alloys were investigated. The results show that LaNi5 and LaMg2Ni9 phases are contained in all experimental alloys. LaNi3 phase disappears and LaNi2 phase appears as x ≥ 0.1 and x ≥ 0.3, respectively. Electrochemical performances have been improved after Co substitution for Ni, for example, the discharge capacity and the high rate dischargeability (HRD) reach the maximum at x = 0.1, and the optimum cycling stability is obtained at x = 0.5. The positive impact of Co on the hydrogen diffusion rate in bulk enhances the HRD, but to high Co content (x ≥ 0.3), the unsatisfied hydrogen desorption capability brings relative low HRD compared with the alloy electrode at x = 0.1.

The electrochemical hydrogen storage properties and mechanisms of the Ti 55 V 10 Ni 35 quasicrystal + xLiH(x = 3, 6 and 9 wt.%) system are investigated and discussed in this paper. A composite material in the Ti 55 V 10 Ni 35 quasicrystal and system has been synthesized moderately by means of mechanical milling under an argon atmosphere, which can avoid reaction of releasing of hydrogen during the process of milling. The results indicate that the addition of LiH significantly improves the electrochemical characteristics of composite material. The maximum discharge capacity increases from 220.1 mAh/g to 292.3 mAh/g on Ti 55 V 10 Ni 35 + 6 wt.% LiH, and the cycling stability is also enhanced too. In addition, the high rate dischargeability (HRD) is ameliorated remarkably, and the value of HRD value at 240 mA/g rises by 78.1%–87.8% for Ti 55 V 10 Ni 35 + 6 wt.% LiH alloy electrodes. The improvement of characteristics of the electrochemical hydrogen storage characteristics may be attributed to LiH, which has excellent electrochemical activity.

In this work, pressing pressure on microstructure and mechanical properties of non-alloyed powder metallurgy (PM) steels were investigated. The mixed powders prepared in the predetermined proportions were pressed unidirectionally under 650, 700, 750, 800 and 850 MPa. Samples of the tensile experiment were turned into blocks by squeezing with the mould which had been prepared according to ASTM (E 8M) standards of powder metal material tension sample. The pressed samples were sintered at argon atmosphere at 1200oC for 1 hour. The microstructure of the PM steels was characterised by optic microscope, SEM and EDS. Results indicated that PM steel pressed at 750 MPa showed the highest values of yield strength and ultimate tensile strength. However, when the amount of pressing pressure increased from 750 MPa to 850 MPa, yield strength, ultimate tensile strength and elongation decreased. Keywords: Powder metallurgy, powder metallurgy steels, pressing pressure, microstructure, mechanical properties