Series Of Alloys Research Articles

Magnetism, phase transition, and magnetocaloric effects of Co2Nb0.8Ga1.2 and Co2Nb1.2Ga0.8 Heusler alloys

Magnetism, phase transition, and magnetocaloric effects of Co2Nb0.8Ga1.2 and Co2Nb1.2Ga0.8 alloys were studied. The measured data show that the TC of Co2Nb1.2Ga0.8 and Co2Nb0.8Ga1.2 are 390 K and 250 K, respectively. Interestingly, calculated the high magnetic susceptibility and spontaneous magnetic moment special magnetic behavior was discovered. The spin fluctuation theory was used to prove the character of flowing electron ferromagnet characteristics in this series of alloys find the T0 and TA of the Co2Nb0.8Ga1.2 alloy are 0.268×103 K, and 0.984×103 K, respectively. Meanwhile, from the magnetocaloric effect, it can be found that the isothermal magnetic entropy change ΔSM was 1.8 J/kg⋅K of under a 5 T field while possessing a large refrigeration temperature region. The results show that changing the ratio of the Nb atom to the Ga atom can effectively reduce the Curie temperature and lay the foundation for the subsequent design of room temperature refrigerants.

Strategies for regeneration of Pt-alloy catalysts supported on silica for propane dehydrogenation

Catalyst stability, resistance to deactivation, and regeneration remain a challenge for high temperature reaction processes. For Pt alloys used in propane dehydrogenation (PDH), the primary pathways of catalyst deactivation include coke formation and metal nanoparticle sintering over time. Recent work shows that silica-supported catalysts provide excellent selectivity for this reaction, but the regenerability of silica-supported catalysts has not been established. In this work, we study a series of Pt alloys, including PtMn, PtZn, and PtSn, for the PDH reaction at 550 °C and 600 °C, and we subject the catalysts to regeneration over multiple cycles. While oxidation in air restores the reactivity completely with minimal catalyst sintering, it is surprising to find that these catalysts can also be regenerated in pure hydrogen. Here we explore the types of coke formed on these catalysts using in situ temperature programmed oxidation (TPO). Two types of coke are found: one on the metallic NP surface, and a second on the silica support. Our work shows that treatment in hydrogen causes redistribution of the coke between the metal and support, which can restore most catalytic activity lost during a reaction run. Periodic introduction of H2 during a reaction cycle may constitute an unexplored strategy for extending the lifetime of PDH catalysts.

High-Strength Ductility Joining of Multicomponent Alloy to 304 Stainless Steel Using Laser Welding Technique

In this work, a series of multicomponent alloys (CoCrFeNi, CoCrNi, and CoNiV) were laser welded with 304 stainless steel (304ss), and detailed comparisons on microstructural characteristics and mechanical properties were conducted for dissimilar laser welded joints. It is revealed that all of the dissimilar laser welded samples possessed defect-free joints and the corresponding fusion zone consisting of fcc single-phase showed homogeneous element distribution accompanied by a narrow element gradient in the vicinity of the fusion zone boundary. After laser welding with identical welding parameters, equiaxed grain was observed on the side of multicomponent alloy, while coarse columnar grain was obtained on the side of 304ss. Especially, the columnar grains of the fusion zone on the side of 304ss disclosed preferential <001> growth direction in the CoCrFeNi/304ss and CoCrNi/304ss welded joints. Furthermore, all of the dissimilar laser welded joints were fractured in the fusion zone, attributing to the drastic loss of strength in the fusion zone with coarsened grain. It is worth noting that a special lamellar structure that merged by dimples was found in the fracture surface of the CoNiV/304ss joint, closely related to the existence of the V-enriched region. Finally, a high strength-ductile synergy can be achieved by laser welding CoNiV alloy to 304ss, which showed a yield strength of 338 MPa, ultimate tensile strength of 686 MPa, and total elongation of 28.9%. These excellent mechanical properties prevailed in the potential of a CoNiV/304ss laser welded joint to be applied as a structural material.

Development of Materials for Solid State Hydrogen Storage

Series of high entropy alloys designed on Hume-Rothery criterion was prepared and the probability of the empirical approach to hydrogen storage materials preparation was investigated. Calculated HEA’s with equimolar compositions were selected from the list of alloys with limited VEC (valence electron concentration), ΔS and ΔH. The phase composition of prepared materials was compared with the prediction model and material characteristics such as chemical composition, and phase composition were studied. In this article material characterization of predicted high-entropy alloys with various prediction parameters values will be presented in terms of empirical prediction methods for solid-state hydrogen storage materials.

Effect of Vanadium Addition On Structure And Soft Magnetic Properties of Nanocrystalline FeCoZrBCu Melt Spun Alloys

In this report, glass forming ability, structure and soft magnetic properties of melt spun ribbons of (Fe1-xCox) 88-yVyZr7B4Cu1alloys with compositions x0.1y2, x0.1y4 and x0.1y6 &amp; x0.35y2, x0.35y4 and x0.35y6 have been investigated. All alloys were found to be fully amorphous after melt spinning. Annealing of amorphous ribbons of x0.1 series alloys leads to the formation of bcc α-Fe(Co) phase and Fe2Zr phase in the amorphous matrix, while annealing of amorphous ribbons of x0.35 series alloys, leads to the formation of only bcc α-Fe(Co) phase in the amorphous matrix. High precision lattice parameter calculation revealed that V addition influences the phase formation in low Co containing x0.1 alloys. It leads to low volume fraction of bcc α-Fe(Co) phase and promotes Fe2Zr phase. A higher Co content increases the Curie temperature of amorphous phase, while V addition decreases the TC of amorphous phase in both x0.1 and x0.35 series of alloys. Saturation magnetization (Ms) of x0.35 alloys are higher than of x0.1 alloy due to higher Co content and the Ms decreases with increasing V content due to its non-magnetic nature. Coercivity was found to be increased with annealing in x0.35 alloys due to the low volume fraction formation of bcc α-Fe(Co) phase and Fe2Zr phase. The coercivity decreases with increasing V addition in x0.35 alloys as spun ribbons and a lowest coercivity of 0.13 Oe has been obtained in x0.35y6 alloy which is one of the lowest among FeCoZrBCu alloys reported.

Lanthanide-Based Coordination Polymers Molecular Alloys Stability: A Thermochemical Approach

In this study, we investigate the thermodynamics of lanthanide-based coordination polymer molecular alloys. We demonstrate that if lanthanide ions have many chemical similarities, the solubility of homo-lanthanide-based coordination polymers can vary significantly from one lanthanide ion to another. Indeed, we experimentally determine the solubility constants of a series of isostructural homo-lanthanide coordination polymers, with general chemical formula [Ln2(bdc)3(H2O)4]∞ with Ln = La-Er plus Y and where bdc2- symbolizes 1,4-benzene-di-carboxylate. Then, we extend the study to two series of isostructural molecular alloys with general chemical formula [Ln2xLn'2-2x(bdc)3(H2O)4]∞ with 0 ≤ x ≤ 1 based either on heavy ([Eu2xTb2-2x(bdc)3(H2O)4]∞) or light ( [Nd2xSm2-2x(bdc)3(H2O)4]∞) lanthanide ions. We found that whatever the solubility difference of the homo-nuclear compounds is, the configurational entropy is the main driving force of the stabilization of molecular alloys.

Quasicrystal-strengthened biomedical magnesium alloy fabricated by laser additive manufacturing

Magnesium (Mg) alloy, particular Mg-zinc (Zn) series alloy, owns great potential as implant materials, despite it shows uncontrollable corrosion rate and inadequate mechanical performance. Herein, alloying treatment with rare earth yttrium (Y) was adopted to improve the overall performance of Mg-Zn-Zr alloy. In detail, Mg-Zn-Y-Zr (ZW61) parts were fabricated using laser additive manufacturing. Results showed that Y addition had contributed to the formation of quasicrystal I-phase (Mg3Zn6Y), which could serve as weak cathode and alleviate the occurrence of micro-galvanic corrosion within Mg matrix. Meanwhile, Y addition also promoted the development of compact corrosion film, which further delayed the corrosion of Mg matrix. Thus, laser-processed ZW61 parts showed a considerably reduced corrosion rate of 0.67 mm/year. More importantly, the quasicrystal I-phase contributed to a more significant Orowan strengthening effect, as it exhibited a near-coherent interface with α-Mg. Besides, rare earth Y decreased the energy of stacking faults, and thereby activated numerous non-basal slip systems during deformation, as proved by TEM observation. Thus, as-built ZW61 part showed simultaneously improved strength and plasticity. Furthermore, in vitro cell testing proved its favorable biocompatibility. Our research exhibited that laser-processed ZW61 was a competitive candidate for orthopedics device application.

Tribological mechanism of carbon group nanofluids on grinding interface under minimum quantity lubrication based on molecular dynamic simulation

Carbon group nanofluids can further improve the friction-reducing and anti-wear properties of minimum quantity lubrication (MQL). However, the formation mechanism of lubrication films generated by carbon group nanofluids on MQL grinding interfaces is not fully revealed due to lack of sufficient evidence. Here, molecular dynamic simulations for the abrasive grain/workpiece interface were conducted under nanofluid MQL, MQL, and dry grinding conditions. Three kinds of carbon group nanoparticles, i.e., nanodiamond (ND), carbon nanotube (CNT), and graphene nanosheet (GN), were taken as representative specimens. The [BMIM]BF4 ionic liquid was used as base fluid. The materials used as workpiece and abrasive grain were the single-crystal Ni-Fe-Cr series of Ni-based alloy and single-crystal cubic boron nitride (CBN), respectively. Tangential grinding force was used to evaluate the lubrication performance under the grinding conditions. The abrasive grain/workpiece contact states under the different grinding conditions were compared to reveal the formation mechanism of the lubrication film. Investigations showed the formation of a boundary lubrication film on the abrasive grain/workpiece interface under the MQL condition, with the ionic liquid molecules absorbing in the groove-like fractures on the grain wear’s flat face. The boundary lubrication film underwent a friction-reducing effect by reducing the abrasive grain/workpiece contact area. Under the nanofluid MQL condition, the carbon group nanoparticles further enhanced the tribological performance of the MQL technique that had benefited from their corresponding tribological behaviors on the abrasive grain/workpiece interface. The behaviors involved the rolling effect of ND, the rolling and sliding effects of CNT, and the interlayer shear effect of GN. Compared with the findings under the MQL condition, the tangential grinding forces could be further reduced by 8.5%, 12.0%, and 14.1% under the diamond, CNT, and graphene nanofluid MQL conditions, respectively.

Effective Mg Incorporation in CdMgO Alloy on Quartz Substrate Grown by Plasma-Assisted MBE

The development of CdMgO ternary alloy with a single cubic phase is challenging but meaningful work for technological advancement. In this work, we have grown a series of Cd1-xMgxO ternary random alloys with various Mg concentrations (x = 0, 30, 32, 45, and 55%) on quartz substrate by plasma-assisted molecular beam epitaxy (PA-MBE) technique. The structural investigations of alloys were performed using the X-ray diffraction (XRD) technique. The decreases in average crystallite size and lattice parameters were observed with an increase in Mg content in the alloys. XRD analysis confirms a single cubic phase is obtained for alloy compositions. The elemental and morphological studies were carried out using energy dispersive x-ray (EDX) spectroscopy and atomic force microscope (AFM) technique, respectively. The optical investigation was carried out using UV-Vis spectroscopy. The optical bandgaps were estimated using the Tauc relation and it was varied from 2.34 eV to 3.47 eV by varying the Mg content from zero to 55% in the alloys. The Urbach energy increases from 112 meV to 350 meV which suggests a more disordered localized state with an increase in Mg incorporation in the alloys.

Unusually high corrosion resistance in Mo CrNiCo medium entropy alloy enhanced by acidity in aqueous solution

• A series of ultra-corrosion-resistant medium entropy alloys were developed. • The corrosion resistance of our alloys unusually increases with acidity in Cl − containing solutions. • The unique anti-corrosion behaviour results from the formation of a protective and compact medium entropy oxide film, which can be attributed to the synergic effect of the chemical complexity on absorption of H 2 O and O 2 . High corrosion resistance of alloys is essential for their structural applications; however, most alloys suffer from degradation of their corrosion resistance with the increasing acidity of their surroundings. Nonetheless, we developed a series of medium-entropy alloys (MEAs) in this work, which exhibit high strength, superior fracture toughness and ultra-high corrosion resistance, outperforming the variety of corrosion resistant alloys hitherto reported. Most interestingly, our MEAs exhibit an unusual anti-corrosion behavior and their corrosion resistance increases with acidity in Cl − containing solutions. Through extensive thermodynamic calculations, density functional theory (DFT) simulations and experiments, we reveal that the unusual anti-corrosion behavior of our MEAs can be attributed to their surface chemical complexity, which facilitates the physio-chemical-absorption of H 2 O and O 2 and thus the rapid formation of metastable medium entropy passive films that contain the lowest amount of defects, as compared to the passive films on conventional alloys reported in the literature.

Scalable Synthesis of Bimetallic CoFe Alloy Nanoparticles for Efficient Oxygen Evolution Reaction

AbstractThe development of efficient electrocatalysts towards oxygen evolution reaction (OER) is critical for large‐scale applications of electrochemical water splitting and metal‐air cells. Usually, transition metal alloys exhibit superior activity for OER. Herein, we successfully prepared a series of scalable transition metal alloys with homogeneous size by a facial sol‐gel self‐propagating combustion method. Among them, the CoFe alloy displayed the highest oxygen evolution reaction (OER) activity, achieving an overpotential of 310 mV at 10 mA cm−2. After running OER tests for 48 h, the activity of CoFe alloy hardly decayed, indicating its outstanding stability. This work may make some contributions to the production of promising transition metal alloy catalysts and related energy equipment applications.

Creep Behavior of Squeeze-Cast Mg–15Gd Alloy

The creep behavior of a binary Mg-15 wt.% Gd alloy was investigated over the temperature range from 523 K to 743 K, i.e., in both the single-phase region (the hexagonal close-packed solid solution of Gd in Mg) and the two-phase region (the solid solution plus Mg5Gd precipitates). The alloy was prepared by the squeeze casting technique. In the higher temperature range, at 723 and 743 K, the specimens were solution treated by in situ annealing prior to testing. At the temperature of 673 K and below, the alloy was tested in the cast state. In the higher temperature range, the behavior was interpreted in terms of the viscous glide, where the dislocation motion was constrained by the presence of solute atmospheres. The dislocation motion was controlled by the rate of the cross slip from the basal to the prismatic planes. At the temperatures of 623 K and 673 K, the creep behavior was rationalized by introducing the threshold stress concept. At the temperatures of 523 K and 573 K, the stresses required to achieve experimentally measurable creep rates were such that dislocations broke away from the atmospheres of foreign atoms. Comparison with a series of magnesium alloys prepared by squeeze casting and creep-tested by the same technique showed that gadolinium can be a favorable creep-resistance enhancing element.

The influence of NbB inoculation on dendritic spacing and grain size of an aluminum 2017 alloy at different cooling rates

The Al-4Cu-Mg 2017 alloy is a significant Al extrusion alloy. As a result, knowing its behavior in terms of grain refining during casting stages becomes critical for the next processing steps. In the face of the shortcomings exhibited by TiB inoculants, the addition of NbB could be tested for this alloy as an alternative. The present article investigates the effects of NbB addition on grain size (GS), on secondary dendrite arm spacing (λ2), and on hardness of centrifugally cast (CC) and directionally solidified (DS) 2017 alloy samples, encompassing a broad range of cooling rates and solidification conditions. The λ2 did not change much as a result of the NbB inoculation, either for DS or CC samples, decreasing from 7.2 to 7.0 μm in the case of the 4-mm-thick CC samples and increasing from 17.0 to 22.5 μm in the case of the DS samples. The average GS, on the other hand, reduced from 293 to 136 μm for the NbB-containing CC samples and from 756 to 313 μm for the DS samples associated with cooling rates of 10 K/s. Both processes can achieve nearly the same GS reduction ratio, namely 2.2 for the CC and 2.5 for the DS. This implies that GS reduction ratio was barely affected if similar cooling rates were compared while taking the experimental range for both processes into account. Moreover, Vickers hardness results revealed that GS had little influence on this property for both alloys studied. The experimentally obtained data translated a variety of solidification condition outlines for the 2017 alloy. Through this data, the understanding of an alternative inoculant in a significant Al alloy series advanced significantly.

A Weldment Characteristics on Laser Welding of 2XXX Aluminum Alloys

In the aerospace industry, high-strength heat-treated aluminum alloys are increasingly being used for large wing structures, which are typically designed by welding thin skins to a pocketed frame structure to reduce weight. Owing to the limited welding area between the frame and the skin and the limited space in the chamber, laser welding is the most suitable manufacturing process. Therefore, the weld-ability and the strength of laser-welded aluminum frame-skin structure must be determined. In this study, AA2219 of the A2XXX alloy series was tested under various welding conditions. Analysis of the bead shape in the cross-section of the welded frame?skin revealed that the optimal welding conditions can be achieved when the ratio of the bead width to penetration (L/H) is minimal. The weld-ability of AA2219 was compared to that of AA2024 by examining the 1) spatter and porosity, 2) hardness in the heat-affected zone, and 3) tensile strength of the two alloys welded under the determined optimal welding conditions. The tensile strength of laser-welded AA2219 and AA2024 was 79% and 70% of that of the base material, respectively. Because the tensile strength value of the welded AA2219 was nearly equal to the yield strength value of the base material, the AA2219 laser-beam welding process can be applied to large wing structures.

Research on diffusion wear mechanism of WC tool cutting Al2024 based on MD

Al2024 belongs to a typical Al-Cu-Mg series alloy. It has the advantages of high-strength, low-specific gravity, stress resistance, corrosion resistance, good heat resistance, and high fatigue resistance. It is widely used in aerospace, automobiles, ships, chemicals, and other fields. Aluminum alloys play a pivotal role in industry and manufacturing. Cemented carbide tools are often used in the processing of aluminum alloys, and diffusion wear is prone to occur during the processing. It is of great significance to study the diffusion phenomenon of WC tools in the process of cutting aluminum alloys for improving tool life and workpiece surface machining accuracy. In this paper, based on the molecular dynamics (MD) simulation method, the WC tool and the Al2024 model were established, the Morse potential parameters between the tool and the workpiece atoms were calculated, and the diffusion wear mechanism of the WC tool in the process of cutting Al2024 was studied. Through the displacement nephogram in the tool-worker X direction, it is found that the workpiece atoms have a tendency to diffuse to the tool. Using the mean square displacement (MSD) method, the diffusion velocities of Al, Cu, and Mg atoms in the workpiece were obtained. The results show that the activation energy of atomic vacancies at the grain boundary is smaller than that at the lattice, and the Al, Cu, and Mg atoms at the grain boundary of the workpiece are more likely to diffuse, and the diffusion rate of Mg atoms is the fastest. The total energy of single atoms in the cutting process was analyzed, and it was found that the energy required for Al, Cu, and Mg elements at the grain boundary of the workpiece to diffuse into the WC tool and the energy required for the Mg and Al elements at the workpiece lattice to diffuse into the WC tool were satisfied.

A dual functional Ti-Ga alloy: inhibiting biofilm formation and osteoclastogenesis differentiation via disturbing iron metabolism

BackgroundAlthough biomedical implants have been widely used in orthopedic treatments, two major clinical challenges remain to be solved, one is the bacterial infection resulting in biofilm formation, and the other is aseptic loosening during implantation due to over-activated osteoclastogenesis. These factors can cause many clinical issues and even lead to implant failure. Thus, it is necessary to endow implants with antibiofilm and aseptic loosening-prevention properties, to facilitate the integration between implants and bone tissues for successful implantation. To achieve this goal, this study aimed to develop a biocompatible titanium alloy with antibiofilm and anti-aseptic loosening dual function by utilizing gallium (Ga) as a component.MethodsA series of Ti-Ga alloys were prepared. We examined the Ga content, Ga distribution, hardness, tensile strength, biocompatibility, and anti-biofilm performance in vitro and in vivo. We also explored how Ga3+ ions inhibited the biofilm formation of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and osteoclast differentiation.ResultsThe alloy exhibited outstanding antibiofilm properties against both S. aureus and E. coli in vitro and decent antibiofilm performance against S. aureus in vivo. The proteomics results demonstrated that Ga3+ ions could disturb the bacterial Fe metabolism of both S. aureus and E. coli, inhibiting bacterial biofilm formation. In addition, Ti-Ga alloys could inhibit receptor activator of nuclear factor-κB ligand (RANKL)-dependent osteoclast differentiation and function by targeting iron metabolism, then suppressing the activation of the NF-κB signaling pathway, thus, showing their potential to prevent aseptic loosening.ConclusionThis study provides an advanced Ti-Ga alloy that can be used as a promising orthopedic implant raw material for various clinical scenarios. This work also revealed that iron metabolism is the common target of Ga3+ ions to inhibit biofilm formation and osteoclast differentiation.

A comparative study on the corrosion performance of four FeCrAl alloys with different Cr contents in contact with oxygen-saturated LBE

The corrosion behavior of a series of FeCrAl alloys with four Cr contents was investigated in static oxygen-saturated liquid lead–bismuth eutectic (LBE) at 600 °C for 720 h. The oxidation layer had a triple-layered structure composed of an external magnetite layer, a middle Fe–Cr spinel layer, and an inner oxide zone. Characterization of the FeCrAl alloys after corrosion in the static liquid LBE showed that the corrosion behavior was dependent on the Cr content. The corrosion appearances and mechanisms were studied, and the oxygen diffusion processes that may have occurred during corrosion were discussed.

Bauschinger effect in Gd micro-alloying metastable high-entropy alloy

To investigate Bauschinger effect in metastable high-entropy alloys with strain-induced FCC → HCP phase transformation, we designed a series of Gd micro-alloying non-equiatomic metastable high-entropy alloys. The results show that all tested alloys have asymmetrical tension-compression properties exhibiting the obvious Bauschinger effect, which is related to the different levels of phase transformation in compression and tension owing to different deformation textures. Excessive phase transformation suppresses the increase in pile-up density of geometrically necessary dislocations (GNDs), resulting in a back stress relaxation effect. The inverse phase transformation observed by quasi in-situ EBSD proves the instability of the HCP phase. The established kinetic model points out limitation of the classical back stress measurement method in metastable high-entropy alloys.

AUSTRAL WRIGHT 5251

Abstract Austral Wright 5251 is a wrought, non-heat-treatable, aluminum-magnesium-manganese alloy (5xxx series). It is about mid-way in the series of aluminum-magnesium alloys for alloying content and strength, which is very similar to that of alloy 5052. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Al-494. Producer or source: Austral Wright Metals.

Study of Tribological Properties of Bulk Nanostructured Aluminum and Copper Samples Applicable in Automotive Bearing Application

Using lightweight systems and friction reduction approaches are two main contributors towards modern and efficient powertrains in the automotive industry. New materials and processes are required to achieve the demanding and ever-increasing performance requirement of automotive systems. Nanostructure induced by severe plastic deformation methods involves bimodal microstructures and hence, shows exceptional mechanical characteristics which can be exploited for automotive application. Through this study, samples were prepared using pure copper, aluminum alloy (series 7000) and were processed to attain bulk nanostructured samples using a Single Step High Pressure Torsion technique with appropriate dimensions applicable as the rolling elements of automotive bearings. The induced nanostructures resulted micro hardness and frictional characteristics of the bulk samples were assessed using transmission electron (TEM) and atomic force (AFM) microscopies as well as microhardness evaluations. The results revealed that a fully refined nanostructured samples were achieved with 90% increase in the hardness at the outer diameter of the sample. The AFM measurements indicated that the friction coefficient of nanostructured copper and aluminum samples were ~ 25 and ~ 45% less than that of both the unprocessed samples, respectively. Characteristics of treated samples suggest that these processes can be potentially used in demanding conditions of rolling element bearings with reduced weight and frictional losses.