Types Of Alloys Research Articles

Effect of Mn content in the Ti/Zr-based AB2 Laves type alloys on their electrochemical performance

In this work, we studied the impact of Manganese content on the structural and electrochemical properties of the AB2 Laves phase alloys. These multicomponent alloys were composed of 7 individual constituents with a composition Ti0.15Zr0.85La0.03V0.12Mn0.7+xFe0.12Ni1.2 and a variable Manganese content, x = 0.021, 0.035, 0.070. The alloys were prepared using arc melting and rapid solidification techniques. These alloys were characterized by X-ray diffraction and Scanning Electron Microscopy with X-ray Energy Dispersive Spectroscopy allowing to probe the phase-structural composition of the alloys, their microstructures, and elemental distribution among the phase constituents. The rapidly solidified alloys exhibited refined microstructures with a more uniform elemental distribution compared to their as-cast counterparts, the latter containing larger grain sizes and clustered La-rich phases. C15 and C14 Laves type structures contributed to the phase-structural composition of the alloys, with their proportions influenced by the Manganese content and the chosen preparation method. The study revealed a multi-feature relationship between the Manganese content, the phase abundances, and the electrochemical performances, with notable disparities between as-cast and rapidly solidified alloys. The alloy containing 3 wt% Manganese demonstrated the highest discharge capacity and superior activation performance for both preparation methods, suggesting the best choice when optimizing the composition of the anodes for achieving the best battery performance. The highest hydrogen diffusion rate was observed for the alloy containing 10 wt% Manganese which can be related to the catalytic role of Manganese in the processes of hydrogen exchange when present in these alloys.

Microstructure and Erosion Wear of In Situ TiC-Reinforced Co-Cr-W-C (Stellite 6) Laser-Cladded Coatings.

The article presents research results on the possibility of shaping the structure and properties of Co-Cr-W-C-Ti alloys (type Stellite 6) using laser cladding technology. Cobalt-based alloys are used in several industries because they are characterized by high erosion, abrasion, and corrosion resistance, retaining these properties at high temperatures. To further increase erosion resistance, it seems appropriate to reinforce material by in situ synthesis of hard phases. Among the transition metal carbides (TMCs), titanium carbide is one of the hardest and can have a positive effect on the extension of the lifetime of components made from cobalt-based alloys. In this article, concentration of C, W, and Ti due to the possibility of in situ synthesis of titanium carbides was subjected to detailed analysis. The provided research includes macrostructure and microstructure analysis, X-ray diffraction (XRD), microhardness, and penetrant tests. It was found that the optimal concentrations of Ti and C in the Co-Cr-W-C alloy allow the formation of titanium carbides, which significantly improves erosion resistance for low impact angles. Depending on the concentrations of titanium, carbon, and tungsten in the molten metal pool, it is possible to shape the alloy structure by influencing to morphology and size of the reinforcing phase in the form of the complex carbide (Ti,W)C.

Effect of deep cryogenic treatment on improving the high-temperature impact resistance of Al–Zn–Mg–Cu alloy

The aging Al–Zn–Mg–Cu alloy exhibits a significant decrease in performance after undergoing thermal shock. In order to improve the resistance of this type of alloy to thermal shocks, the influence of deep cryogenic treatment (DCT) on the high temperature mechanical properties and microstructure of thermal shocked Al–Zn–Mg–Cu alloy is investigated in this paper. It was found that the mechanical properties of Al–Zn–Mg–Cu alloys decrease significantly with the increase of electric heating temperature. The deep cryogenic treatment reduced the grain size of Al–Zn–Mg–Cu alloy, increased the density of the precipitates, and also inhibited the coarsening of the precipitates. Therefore, the deep cryogenic treatment can slow down the weakening effect of Al–Zn–Mg–Cu alloy at high temperatures.

Different TBS and Grain Numbers on Mechanical Behavior of FeNiCrCoCu High-Entropy Alloys: A Molecular Dynamics Simulation

High-entropy alloy (HEA) is a type of alloy that exhibits high hardness, strength, good wear resistance, corrosion resistance, and versatility. Molecular dynamics simulations were conducted to illustrate the microscopic evolution of FeNiCrCoCu HEAs under varying twin boundary spacing (TBS). Compression revealed dislocation migration, variations in the quantity and radius of nanovoids, as well as grain boundary diffusion. With increasing strain, high-energy regions expand on the surface of the crystal, transitioning from an initially smooth state to uniform deformation accompanied by grain boundary diffusion, while dislocations occur within the crystal. The number and radius of observed nanovoids within the crystal increase. The mechanical characteristics of FeNiCrCoCu HEAs are influenced by the TBS size. The alloy demonstrates better mechanical properties when the TBS is 1.22[Formula: see text]nm. FeNiCrCoCu HEAs with a constant TBS showed improved mechanical characteristics when a greater number of grains ([Formula: see text]) were present.

Atomistic insights into friction and wear characteristics of M50 bearing steel: a molecular dynamics simulation study

ABSTRACT M50 bearing steel is a typical alloy material widely used in aeroengines due to its high hardness and fatigue life at high temperatures. To reveal the frictional mechanisms and wear behaviours of contact and sliding, a molecular dynamics simulation model consisting of an indenter and substrate is constructed. The results indicate that, during the indentation process, the normal load exhibits a linear relationship with the indentation depth at shallow depths. With further penetration, the substrate generates severe deformations and subsurface damages. Throughout the scratching process, the average friction force exhibits a linear increase with the growing scratching depth, while the coefficient of friction decreases. Surface morphologies and shear strain distributions are analyzed to elucidate plastic deformation and atomic displacement. Moreover, the wear atom shows a linear proportionality to both scratching distance and depth. These findings enhance understanding of frictional properties and atomic wear behaviour of M50 bearing steel during contact and sliding, potentially informing bearing failure prediction and material optimization.

An in vitro evaluation of bond strength and failure behavior between 3D-printed cobalt-chromium alloy and different types of denture base resins

ObjectivesThis study aimed to evaluate the shear bond strength and failure behavior between cobalt-chromium (Co-Cr) alloy and different types of denture base resins (DBRs) over time. MethodsSeventy-two disk-shaped specimens (8 mm in diameter and 2 mm in thickness) were manufactured using a selective laser melting technology-based metal 3D printer. Three types of DBRs were used: heat-cure (HEA group), cold-cure (COL group), and 3D-printable (TDP group) DBRs (n = 12 per group). Each DBR specimen was fabricated as a 5 mm × 5 mm × 5 mm cube model. The specimens of the TDP group were manufactured using a digital light processing technology-based 3D printer. Half of the DBRs were stored in distilled water at 37 °C for 24 h, whereas the remaining half underwent thermocycling for 10,000 cycles. Shear bond strength was measured using a universal testing machine; failure modes were observed, and metal surfaces were evaluated using energy dispersive spectrometry. ResultsThe shear bond strength did not differ between the DBR types within the non-thermocycled groups. Contrarily, the TDP group exhibited inferior strength compared to the HEA group (P = 0.008) after thermocycling. All three types of DBRs exhibited a significant decrease in the shear bond strength and an increased tendency toward adhesive failure after thermocycling. ConclusionsThe bond strength between 3D-printable DBRs and Co-Cr alloy was comparable to that of heat-and cold-cure DBRs before thermocycling. However, it exhibited a considerable weakening in comparison to heat-cure DBRs after simulated short-term use. Clinical SignificanceThe application of 3D-printable DBR in metal framework-incorporated removable partial dentures may be feasible during the early phase of the treatment. However, its application is currently limited because the bond strength between the 3D-printable DBR and metal may weaken after short-term use. Further studies on methods to increase the bond strength between these heterogeneous materials are required.

Elucidating different selective corrosion behavior of two typical marine aluminum bronze alloys from the perspective of constituent phases

The selective corrosion behavior of two typical marine aluminum bronze alloys (i.e., NAB and MAB) were investigated comparatively. The characteristics of each constituent phase in NAB and MAB including composition, morphology, distribution and work function were analyzed, and their roles in the micro-corrosion behavior were elucidated. MAB exhibits de-alloying corrosion, whereas NAB shows localized selective phase corrosion. The crucial factor causing different selective corrosion behavior is the morphology and distribution of constituent phases. The results reveal correlations between selective corrosion behavior and microstructure and provide insights into improving corrosion resistance of aluminum bronze alloys on the concept of microstructure tailoring.

Effect of Movement Kinematics and Heat-Treated Alloys on the Apical Extrusion of Debris: An In Vitro Study

Background: Apically extruded debris can be affected by some features of the file systems such as kinematics or metallurgic properties. Aims: This in vitro study aimed to evaluate the effect of movement kinematics (reciprocation or rotation) and heat-treated alloys (C.Wire) on the amount of debris extrusion. Methods: Seventy-two mesiobuccal root canals were assigned into three experimental groups related to the single-file system used (n = 24): two rotational; One Shape (Conventional Ni-Ti), One Curve (C.Wire), and one reciprocating; and One Reci (C.Wire). The file systems were used according to the advisable speed and torque according to the manufacturers’ suggestion. The weight of debris was calculated by subtracting the preweights from postweights of Eppendorf tubes. Kruskall–Wallis and Mann–Whitney U tests were used to analyze the data (P = 0.05). Results: One Shape produced the greatest amount of extruded debris compared with One Curve (P < 0.001) and One Reci (P < 0.001), respectively. No statistical difference was found between One Curve and One Reci concerning amount of apical debris extrusion (P = 0.489). Conclusion: Metallurgical properties of files may affect apical debris extrusion. Alloy type is an important factor in the amount of debris extrusion. File kinematics does not affect apical debris extrusion.

Restoration of the Impact Crusher Rotor Using FCAW with High-Manganese Steel Reinforced by Complex Carbides

Abstract A new hardfacing alloy within the Fe-Ti-Nb-Mo-V-C alloying system was utilized to restore the working surfaces of cone crusher rotors using Flux-Cored Arc Welding (FCAW). TiC, NbC, Mo2C, VC, Mn, and ferromanganese powders were selected as the base materials for manufacturing the welding wire. The resulting hardfaced layer exhibits a composite structure, with manganese austenite as the matrix and complex solid solution reinforcements with a NaCl structure, closely resembling the formula (Ti0.3Nb0.3Mo0.3)C. The primary advantages of this hardfacing alloy include its capacity for intensive deformation hardening along with high abrasion resistance. The hardness of the hardfaced layer is approximately 47 HRC in the as-deposited state and increases to around 57 HRC after work hardening, surpassing typical hardfacing alloys derived from high manganese steel by about 10 HRC. The efficacy of the alloy was tested in restoring rotors made of Hadfield steel in a PULVOMATIC series crusher model 1145, during the milling of sand-gravel mixtures ranging from 25 to 150 mm into spalls measuring 5 to 20 mm. With an average productivity of approximately 60 tons per hour and a production volume of 300 tons, the utilization of this hardfacing alloy enabled multiple restorations of the rotor while maintaining productivity at a level of 15 thousand tons of spalls.

Номенклатура металлов и сплавов из сарматских могильников Нижнего Поволжья II в. до н.э. – первой половины II в. н.э. по данным РФА

The work presents the results of an analysis of the chemical composition of 82 objects from non-ferrous and precious metals dating from the 4th century BC – the first half of the 2nd century AD and originating from the excavation of funeral monuments located in the Lower Volga region. Basically, the analysis of the chemical composition of non-ferrous metal was carried out for objects characteristic of the ordinary population of the region: mirrors, jewelry, clothing or household items, and details of horse harnesses; importantly, sampling was random. The data obtained by the XRF method are very interesting and demonstrate a change in the nomenclature of leading alloys. So, for the period of the 2nd century BC – the border of eras, there is a significant number of objects from tin as well as from tin-lead bronze, with a slight presence of products from a multicomponent alloy, an alloy with arsenic. For the period of the 1st – the first half of the 2nd century AD, there is a significant change in the leading types of alloys: zinc-containing alloys such as two- and three-component brass dominate the sample; also significantly increased the share of triple bronze, highly alloyed with lead; there are also products made of copper and tin bronze. Silver products made of silver from different samples are present in all stages. Analysis of alloying components and impurities in the identified alloys made it possible to distinguish in the sample of the 2nd century BC –the border of eras, the influence of the North Caucasian center of non-ferrous metalworking; recorded changes in the nomenclature of alloys of the 1st – the first half of the 2nd century AD arose, most likely, under the influence of the North Black Sea center of non-ferrous metalworking. The presence of high-zinc brass objects in the sample during the period of the 1st – the first half of the 2nd century AD also does not exclude the receipt of this type of brass from the production center located in Central Asia, which is characterized by an extremely high zinc content in the alloy.

Empirical tight-binding method for large-supercell simulations of disordered semiconductor alloys

We analyze and present applications of a recently proposed empirical tight-binding scheme for investigating the effects of alloy disorder on various electronic and optical properties of semiconductor alloys, such as the band gap variation, the localization of charge carriers, and the optical transitions. The results for a typical antimony-containing III-V alloy, GaAsSb, show that the new scheme greatly improves the accuracy in reproducing the experimental alloy band gaps compared to other widely used schemes. The atomistic nature of the empirical tight-binding approach paired with a reliable parameterization enables more detailed physical insights into the effects of disorder in alloyed materials.

Development of Ti-Zr-Mn based AB2 type metal hydrides alloys for an 865 bar two-stage hydrogen compressor

This study reports the development of a new Ti-Zr-Mn-based AB2 type hydrogen storage alloys for a two-stage metal hydride hydrogen compressor (MHHC). The hydrogen storage alloys are designed to compress hydrogen from 35 to 865 bar within a temperature difference of 115 °C. High-pressure PCT measurements up to 700 bar were carried out to test the performance of the alloys. The alloys' hysteresis and the plateau slope were reduced by optimizing the composition. The introduction of fugacity correction into the Van't hoff equation reduces the deviation between calculation and actual pressure to 24 bar at a pressure above 350 bar. A precise relation between the Ti/Zr ratio and the desorption pressure is described and helps make a correct design of the alloy composition. The designed alloy shows looses less than 1% of the capacity over 3000 full cycles. The desorption plateau pressure of the alloy is constant within 92% during the whole cycling process. A 2 stages compressor working with two types of alloys offers compression with a temperature range between -20 and 95 °C for the refueling hydrogen vehicles up to 865 bar.

Running-in Period During Sliding Wear of Austenitic Steels

The running-in period during dry sliding wear might determine the evolution to steady-state wear behaviour. To this end, the running-in period during sliding wear of austenitic stainless steel, AISI 316L stainless steel, and Hadfield steel were studied through the testing pin (flat-ended)-on-disk configuration. The effects of the normal load, sliding speed, and alloy type were assessed, and the specific wear rate and strain hardening characteristics were determined. The wear rate was correlated with wear mechanism, friction coefficient, hardening, and roughness to characterize the changes occurring during the running-in period. These changes could influence the responses of these materials to wear during the steady-state period. The stabilization of the specific wear rate and hardness was noted to align with the end of the running-in period.Graphical

Microstructural evolution in doped high entropy alloys NiCoFeCr-3X (X=Pd/Al/Cu) under irradiation

Commonly studied equatomic single-phase FCC high entropy alloys based on 3d transition metals like NiCoFeCr do not provide adequate strength and radiation resistance at high doses for nuclear structural applications. In the current study, the major alloying effects like lattice distortion, ordering and clustering tendencies were investigated by adding low concentration of Pd, Al, or Cu respectively to study the doping effects on the ion irradiation response of NiCoFeCr alloy. The alloys were irradiated with 3 MeV Ni2+ ions at 500 °C to a fluence of 1 × 1017/cm2 at a beam flux of approximately 2.8 × 1012 ions/cm2/s. The microstructural evolution upon irradiation i.e., formation of dislocation networks, radiation induced segregation and precipitation, and void formation were studied in detail. Post-irradiation characterization results showed that a Pd addition leads to a high void nucleation rate but controlled void growth, which may be attributed to increased lattice distortion. In Al added HEA, our microstructural analysis indicates that radiation induced ordered L12 precipitates do not affect void swelling significantly. Cu addition led to Cu precipitation that drastically suppressed dislocation density and void swelling of the alloy. Additionally, a model was developed to qualitatively describe the trend in void swelling of typical FCC alloys under ion irradiation. This model was able to qualitatively explain the suppression and reappearance of void swelling in ion irradiated alloys that generally occurs near the region with peak implanted ion concentration.

Design and optimization of a castability test for copper alloys applied to plaster moulds

The paper deals with the design and execution of the test of the castability into preheated plaster moulds. Castability is an important parameter for the evaluation of foundry alloys. When the metal does not run, it usually causes an irreparable defect in the casting. Therefore, it is necessary to verify this technological property correctly for different types of moulds. The castability test for plaster moulds and bronze is not defined, therefore The Vertical Bar Test was adopted, subsequently modified, and applied to plaster moulds. The models are made of wax and the plaster moulds are made according to the manufacturer's prescription and heated to a predetermined temperature. Copper alloy specifically CuSn10 was selected as the alloy to be investigated.The aim of the experiment is to correctly set up and observe the parameters and the method of performing the castability test using gravity casting technology in plaster moulds. It is assumed, as the casting temperature increases, the run-in length of the metal alloy will increase. An important goal is to obtain relevant results, as many variables affect the progress of the test and so there is a risk of error. Due to the time-consuming nature of producing a real disposable model and mould, any failure to succeed would have an economic impact on the foundry, affecting the price of castings. The new method for evaluating castability in plaster moulds can be applied to other types of alloys when temperature changes occur.

Experimental investigation of wax deposition on multiple steel alloys

Paraffin wax deposition is a flow assurance issue that occurs frequently in subsea crude oil and gas condensate flowlines and pipelines. While some mitigation techniques involve coatings, most wax deposition in the oil and gas industry occurs on bare pipe walls made of various steel alloys. Previously, there has not been any investigation into the possibility of differences in the wax deposition that could be attributed to the different types of steel alloys, and this study set out to fill that gap. A cold finger apparatus with interchangeable fingers was used to generate deposits. Deposits were created from waxy model oils across several bulk oil temperatures and rotational speeds. To cover a wide array of materials, six different steels were tested: A2, A36, 1018, 4130, 304, and 316. These materials range from low-carbon steels to high-chrome content stainless steels. Each cold finger's surface was finished with the same process to create a roughness of 4.6 ± 0.5 mm. Deposit mass, thickness, and composition all showed non-negligible differences between deposits formed on the steels investigated: masses varied by 5–15%, thicknesses varied by 30% or more, and deposit compositions were noticeably skewed. Alloy composition, contact angle, roughness, and thermal conductivity were discussed as possible indicators of the effects an alloy would have on wax deposition. These findings facilitate the comparison and interpretation of the results from wax research literature using different steel alloys as well as the design of laboratory wax testing that more closely resembles field conditions.

Suzuki segregation behavior and mechanism in a Co–Cr–Fe–Ni–Mo high-entropy alloy

The knowledge of the Suzuki effect in compositionally complex CoNiCrMo and CoCrFeNiMo solid-solution alloys is rather limited. In this study, the enrichment of Co and Mo atoms and depletion of Cr, Fe, and Ni atoms were determined within the region of four atomic layers at stacking faults (SFs) in a typical quinary concentrated solid-solution alloy (Co0.95Cr0.8Fe0.25Ni1.8Mo0.475) by using scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. To better understand the Suzuki effect, two-stage first-principles Monte Carlo (MC) simulations each with up to 3000 trial swap steps were performed. First, the simulation results suggested the strong tendency of Mo segregation at the second nearest neighbor (2NN) sites at SFs. Nonetheless, as a further Mo segregation induces the excessively large lattice distortion and intrinsic strain energy, it would be inhibited. It was deemed one potential reason for the finite Mo segregation. Second, the simulations revealed the origin and formation of co-segregation of Co and Mo atoms. The segregated Mo atoms at the 2NN sites attract Co atoms, forming the local D019-type ordering at SFs. As a consequence, the stacking fault energy can reach a strongly negative value below −500 mJ/m2. Meanwhile, the Co/Mo co-segregated SFs have high stability against phase transitions to intermetallics and martensite at 773 K.

Machine learning-enabled prediction of high-temperature oxidation resistance for Ni-based alloys

A machine learning (ML) model was developed to predict the oxidation resistance, with the natural logarithm of the parabolic rate constant (lnkp) as the output. Five algorithms were used to training the model, revealing that backpropagation neural network and gradient boosting exhibited superior performance with an R2 of 0.908 and 0.907. The trained models were employed to predict lnkp for changes in temperature, time, and elemental compositions. At last, promising areas with slower oxidation kinetics in typical commercial alloys were predicted under the guidance of the present ML methods.

Laser powder bed fusion of oxide dispersion-strengthened IN718 alloys: A complementary study on microstructure and mechanical properties

In this study, two new grades of oxide dispersion strengthened (ODS) Inconel 718 (IN718) alloys were designed by the thermochemical CALPHAD method and produced by laser powder bed fusion (LPBF) technique. Alloys designated as IN718-YF and IN718-YFH, that consist Y2O3–FeO and Y2O3–FeO–Hf, respectively, were fabricated with >99.9 % densification using optimized process parameters. CALPHAD calculations were highly consistent with experimental findings, highlighting the formation of Al-containing Y–Ti–O and Y–Hf–O nano-oxides in both alloy types. Texture analyzes revealed no significant texture development in as-built (AB) or heat-treated (HT) alloys. Heat treatment was applied at 1050 °C for 1 h to enhance nano-oxide density. The nano-oxide number density remained similar in IN718-YF while it decreased in IN718-YFH alloy as a result of carbide formation after the heat treatment. Besides, formation of secondary γ′ particles was observed in the IN718-YFH/HT alloy. Even though the yield strengths of IN718-YF and IN718-YFH alloys in both AB and HT conditions were similar, the ductility of IN718-YFH was ∼50 % less in almost all conditions compared to the ductility of IN718-YF. This has been shown to be as a result of irregular shaped micron-sized Y-Hf-O oxides, martensite formation in AB condition, increased amount of carbides and existence of secondary γ′ particles in HT condition in IN718-YFH. High density of stacking faults (SF) forming at the interface of the nano-oxides have been detected in IN718-YF alloys. Besides dislocation/nanoparticle interactions, SFs which are responsible for the delocalization of the deformation improve the ductility of IN718-YF alloys. Overall, high temperature mechanical tests exhibit that both alloys have higher strength with improved ductility compared to the standard IN718 alloys, indicating the contribution of the nano-oxides.

Zr as an Alternative Grain Refiner in the Novel AlSi5Cu2Mg Alloy

Al-Si-Cu-Mg alloys are among the most significant types of aluminum alloys, accounting for 85–90% of all castings used in the automotive sector. These alloys are used, for example, in the manufacturing of engine blocks and cylinder heads due to their excellent specific strength (ratio of strength to specific weight) and superior castability and thermal conductivity. This study investigated the effect of using Zr as an alternative grain refiner in the novel AlSi5Cu2Mg cylinder head alloy. The microstructure of this alloy could not be refined via common Al-Ti-B grain refiners due to its specifically designed chemical composition, which limits the maximum Ti content to 0.03 wt.%. The results showed that the addition of Zr via the AlZr20 master alloy led to a gradual increase in the solidus temperature and to the grain refinement of the microstructure with the addition of as little as 0.05 wt.% Zr. The addition of more Zr (0.10, 0.15, and 0.20 wt.%) led to a gradual grain refinement effect for the alloy. The presence of Zr in the AlSi5Cu2Mg alloy was reflected in the formation of Zr-rich intermetallic phases with acicular morphology. Such phases acted as potent nucleants for the α-Al grain.