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Composite electrochemical coatings (CECs) are perceived as the result of the electrochemical reduction of metal from an electrolyte in which dispersed phase particles are present. During the formation of the coating, particles are included in its volume and a composite layer is formed that has increased performance characteristics. The article discusses a different approach based on crystallization of the strengthening phase from an electrodeposited layer of a Ni–W alloy of nonequilibrium composition. It has been shown that the optimal heat treatment mode, which ensures maximum microhardness, leads to the formation of a nanostructured matrix from a solid solution of tungsten in nickel and the crystallization of NiW and Ni4W reinforcing particles. The structure of such a coating corresponds to the structure of classical CECs. [ABSTRACT FROM AUTHOR]

Grain refinement via severe plastic deformation (SPD) can induce the decomposition of Al–Zn supersaturated solid solution, resulting in strain softening rather than hardening. So far, it is very challenging to improve the strength of binary Al–Zn alloy by refining grains through SPD. Herein, a single-phase supersaturated solid solution nanostructure with relaxed grain boundaries has been successfully generated in Al–21.7 at% Zn alloy by cryogenic high-pressure torsion. Instead of softening, giant hardening is achieved. The nanocrystalline Al–Zn alloy with grain size of 15 nm has an ultrahigh yield strength of about 642 MPa.

Grain refinement via severe plastic deformation (SPD) can induce the decomposition of Al–Zn supersaturated solid solution, resulting in strain softening rather than hardening. So far, it is very challenging to improve the strength of binary Al–Zn alloy by refining grains through SPD. Herein, a single-phase supersaturated solid solution nanostructure with relaxed grain boundaries has been successfully generated in Al–21.7 at% Zn alloy by cryogenic high-pressure torsion. Instead of softening, giant hardening is achieved. The nanocrystalline Al–Zn alloy with grain size of 15 nm has an ultrahigh yield strength of about 642 MPa. Giant hardening has been achieved in Al–Zn alloy with extremely fine nanograins and single-phased supersaturated solid solution under extremely high shear strain via cryogenic high-pressure torsion. [ABSTRACT FROM AUTHOR]

Al-10Si-Mg alloy have been used for die casting and additive manufacturing. In this study, solution-treated Al-10Si-Mg and Al-10Si alloys (mass％) were heat-treated at several temperatures and the linear dimensional changes arising from the heat-treatments were investigated. A theoretical model for calculating the linear dimensional change in Al-Si-Mg ternary alloys was proposed, and the theoretically and the experimentally determined linear dimensional changes were compared. It was found that the linear dimensional changes of Al-10Si-Mg and Al- 10Si alloys were almost the same. In both alloys, the linear dimensional changes increased with the decrease of the heat-treatment temperature. The linear dimensional changes of Al-10Si-Mg and Al-10Si alloys agreed well with the values estimated by the proposed theoretical model. [ABSTRACT FROM AUTHOR]

A bulk Cu 50 Fe 50 (at%) alloy was prepared by mechanical alloying (MA) of elemental Cu and Fe powders for 20 h, followed by the spark plasma sintering (SPS). All the powder and bulk samples were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical and magnetic properties of the bulk samples were also evaluated. From 1 h to about 10 h of milling, the formation of nanocrystalline Cu-rich face-centered cubic solid solution (FCC γ phase) and Fe-rich body-centered cubic solid solution (BCC α phase) was observed. Above 10 h of milling, the γ and α phases merged to form a single-phase face-centered cubic (γS) solid solution till 20 h. Subsequently, the 20 h MA powder was consolidated using spark plasma sintering (SPS) at three different temperatures: 519 ℃ (0.5 T m), 677 ℃(0.6 T m), and 835 ℃ (0.7 T m), where T m is the average melting point of the alloy (1310 ℃). In all three samples, the metastable γS phase decomposed into the nanocrystalline Cu-rich γ and Fe-rich α phases during SPS. Notably, the 0.7 T m sample exhibited a better balance between strength and ductility by demonstrating a compressive yield strength of 886 MPa and an ultimate compressive strength of 1166 MPa with a ductility of 15%. The high strength and ductility are attributed to a bimodal grain size distribution, i.e., a few microns thick and continuous Cu-rich γ grain boundary phase and an intragranular nanocrystalline mixture of γ and α phases. In addition to its excellent mechanical properties, the 0.7 T m sample displayed favorable soft ferromagnetic characteristics exhibiting a saturation magnetization (M s) of 66 emu/g and a coercivity (H c) of 16 Oe. [Display omitted] • Bulk insoluble Cu 50 Fe 50 (at%) alloy is synthesized by mechanical alloying and SPS. • Microstructure exhibits a bimodal grain size distribution of coarse and fine grains. • High strength and ductility achieved due to the presence of bimodal grains. • A unique phase separation diagram is established for Cu-Fe binary system. [ABSTRACT FROM AUTHOR]

We investigated the mechanical alloying (MA) processes of Al and Al2O3 powders via X-ray diffraction analysis, transmission electron microscopy (TEM), and Vickers microhardness. The yield strengths and microstructures of consolidated compacts were evaluated using tensile tests and TEM, respectively. When the amount of oxygen in the MA atmosphere was higher than a certain threshold, Al2O3 particles of about 7 nm were precipitated in the Al grain interior from a supersaturated solid solution (SSS) of AlO due to significant precipitation driving force. Two types of alloyed powders were obtained: Al2O3 particle-dispersed Al nanocomposite and SSS. The consolidated compact of the former exhibited smaller Al grains and higher yield strength than the latter due to the enhancement of the pinning effect on Al grain boundary migration during consolidation. The difference in the nature of the two kinds of powders affected the Al grain sizes and yield strengths of the consolidated compacts. [ABSTRACT FROM AUTHOR]

Carbon has a low solid solubility in bcc tungsten at equilibrium. However, metastable supersaturated solid solutions can be synthesized with magnetron sputtering. Here, we present a systematic study on the phase stability and mechanical properties of such supersaturated W–C solid solutions. Θ–2θ scans show a split of the 200/020 and the 002 peaks for supersaturated films which is explained by a tetragonal distortion of the bcc structure. This split increases with increasing C content and is maximized at 4 at.% C, where we observe an a/b axis of 3.15–3.16 Å and a c-axis of 3.21–3.22 Å. We performed first-principles calculations of lattice parameters, mixing enthalpies, elastic constants and polycrystalline elastic moduli for cubic and tetragonal W–C solid solutions. Calculations show that tetragonal structure is more stable than the bcc supersaturated solid solution and the calculated lattice parameters and Young’s moduli follow the same trends as the experimental ones as a function of C concentration. The results suggest that supersaturated films with lattice distortion can be used as a design approach to improve the properties of transition metal films with a bcc structure.

Comparative investigations of the crystallization of rapidly quenched Al90Y10 and Al87Ni8Y5 ribbons under thermal and deformation effects are carried out by the methods of differential scanning calorimetry and X-ray structural analysis. It is shown that during continuous heating, crystallization of the rapidly quenched Al90Y10 and Al87Ni8Y5 ribbons begins with the formation of a supersaturated solid solution based on α-Al. Moreover, for upon the subsequent heating of the Al90Y10 ribbon, the transition to the crystalline state proceeds through an intermediate stage to form the metastable phase, Al4Y. It is shown that under the action of severe plastic deformation by high-pressure torsion (HPT), at a pressure of 3 GPa with rotation from 0 to 12 revolutions, complete crystallization of these rapidly quenched ribbons does not occur. Crystallization of the Al90Y10 ribbon initiated by deformation proceeds with the formation of the Al4Y metastable phase (after 1 revolution) and the Al2Y phase (after 4 revolutions), while the formation of the latter is not observed in the process of continuous heating of the initial ribbon. Crystallization of the Al87Ni8Y5 ribbon under the action of HPT proceeds with the formation of α-Al crystals after 1 revolution. [ABSTRACT FROM AUTHOR]

Tungsten (W)-based materials attract significant attention due to their superior mechanical properties. Here, we present a chemical approach based on the addition of carbon (C) for increased strength via the combination of three strengthening mechanisms in W thin films. W:C thin films with C concentrations up to ~4 at.% were deposited by magnetron sputtering. All films exhibit a body-centred-cubic structure with strong texture and columnar growth behaviour. X-ray and electron diffraction measurements suggest the formation of supersaturated W:C solid solution phases. The addition of C reduced the average column width from ~133 nm for W to ~20 nm for the film containing ~4 at.% C. The column refinement is explained by a mechanism where C acts as re-nucleation sites. The W film is ~13 GPa hard, while the W:C films achieve a peak hardness of ~24 GPa. The W:C films are ~11 GPa harder than the W film, which is explained by a combination of grain refinement strengthening, solid solution strengthening and increased dislocation density. Additional micropillar compression tests showed that the flow stress increased upon C addition, from ~3.8 to ~8.3 GPa and no brittle fracture was observed.

Al10SiMg alloy have been used for die casting and additive manufacturing. In this study, solution-treated Al10SiMg and Al10Si alloys (mass%) were heat-treated at several temperatures and the linear dimensional changes arising from the heat-treatments were investigated. A theoretical model for calculating the linear dimensional change in AlSiMg ternary alloys was proposed, and the theoretically and the experimentally determined linear dimensional changes were compared. It was found that the linear dimensional changes of Al10SiMg and Al10Si alloys were almost the same. In both alloys, the linear dimensional changes increased with the decrease of the heat-treatment temperature. The linear dimensional changes of Al10SiMg and Al10Si alloys agreed well with the values estimated by the proposed theoretical model. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of fabricating defect-free functionally graded bi-materials (FGMs) with enhanced wear resistance via incorporation of vanadium carbide (VC) into H13 tool steel. Three distinct composite powders containing 1, 3, and 5 wt%VC were prepared through ball-milling and subjected to laser powder bed fusion (LPBF) process to print different composites on top of monolithic H13 in a wide range of process parameters. Almost fully-dense parts were achieved (maximum of 99.8, 99.8, and 99.5% for 1, 3 and 5 wt%VC composite systems, respectively); however, the increase in VC content narrowed down the processability window range from 60 J/mm3 for 1, and 3wt%VC systems to 30 J/mm3 for 5 wt%VC system. The mechanical properties of optimum samples were characterized through microhardness, nanohardness, and wear tests. The incorporation of VC significantly improved the mechanical properties, 17–40% in microhardness, 10–40% in nanohardness, and 20–53% in wear resistance. The underlying reasons behind such an improvement were correlated to the dissolution of VC during the heating stage of the LPBF process and the formation of (V + C)-supersaturated solid solution in large extents as a result of extremely high cooling rates. This study introduces LPBF-processed FGMs as promising candidates for applications in which wear resistance is paramount.

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This study focuses on the difference in microstructural features and physical properties of Al-2Fe and Al-4Fe alloys subjected to large plastic straining. The difference in the intermetallic particle morphology in the initial state is shown to be a key parameter influencing the particle and grain fragmentation process and, as a result, the properties of these two alloys. We demonstrate that the shape and average size of Al-Fe intermetallic particles provide stronger effect on the microstructure evolution during high pressure torsion (HPT) than their volume fraction. The formation of Fe supersaturated solid solution in Al in these two alloys during deformation is discussed in connection to the morphology of the intermetallic phase. The major microstructural attributes, responsible for the solid solution formation, are highlighted.

In the present work, mechanical alloying of a powder mixture of nickel and graphite (up to 15wt%) was carried out in an attrition mill under a nitrogen atmosphere. The as-milled powders were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The 15wt% graphite dissolved into the nickel (exceeding the negligible solid solubility in the nickel-carbon system), thereby forming a supersaturated solid solution of graphite in a nickel matrix. The dissolved graphite occupied interstitial positions along the dislocation edges and at the grain-boundary regions. A three-step graphite dissolution mechanism has been proposed. The associated changes in the nickel lattice, such as changes in the crystallite size (62 to 43 nm), lattice strain (0.12% to 0.3%), and lattice parameter (0.3533 to 0.3586 nm), which led to the formation of the supersaturated solid solution, were also evaluated and discussed. [ABSTRACT FROM AUTHOR]

To introduce boron (B) into the Sn–1.0Ag–0.5Cu (SAC105) solder, based on the thermodynamic calculations, iron (Fe) is a competent carrier component for bonding B and Sn. The Sn–Fe–B master alloys were prepared by mechanical alloying initially; then, the SAC105-0.05(Fe–B) and SAC105-0.1(Fe–B) solder alloys were prepared using 72-h-milling Sn–Fe–B master alloys. The preparation process and the properties of solders were studied in this work. For the Sn–Fe–B master alloys, the results show that with the increase in the ball-milling time, the powder changes illustrate a cold welding–crushing–cold welding cyclic process. Moreover, the supersaturated solid solubility of (Fe–B) increases gradually in the alloys' matrix and the lattice distortion increases to 0.167% after 72-h milling. Meanwhile, the alloying degree is increasingly apparent, and after 72-h milling, the content of B in the Sn matrix reaches 2.38 wt%. For the solder alloys, with the (Fe–B) content increasing, the melting point decreases and a significant grain refinement occurs in the matrix. Compared to the benchmark SAC105, the hardness of SAC105-0.05(Fe–B) and SAC105-0.1(Fe–B) solder alloys prepared by this method is improved by 20.65% and 34.79%, respectively. The present research provides a novel approach for introducing the immiscible component into the lead-free solder alloys. [ABSTRACT FROM AUTHOR]

Abstract Cu-Nb alloys with a Nb concentration range of 0 wt%∼30 wt% were prepared by mechanical alloying (MA) at room temperature. The effects of Nb content on the crystalline refinement process and mechanical properties of the immiscible Cu-Nb system were investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive X-ray detection (EDX), transmission electron microscopy (TEM) and microhardness measurement. Results show that the completed dissolution of Nb in Cu can be achieved in the samples with Nb content less than ∼11 wt% after 100 h milling, although the equilibrium solubility level is nearly zero. The grain size refinement capability of MA-ed Cu-Nb powder is enhanced with increasing Nb content up to 30 wt%. This is because the susceptibility to recovery process becomes reduced, when the amount of Nb solutes segregated into the dislocation of Cu phase is increased. Cu-30wt%Nb powder milled for 100 h, the average Cu grain size is only ∼6 nm. The microhardness of the samples shows an enhancement with increasing Nb concentration. The main strengthening mechanisms of the MA-ed Cu-Nb alloys are linked to the grain size reduction and the dissolution of Nb into Cu matrix. [ABSTRACT FROM AUTHOR]

Nanocrystalline Al-5at.%V and Al-5at.%Ni alloys, prepared by high-energy ball milling and subsequent consolidation under uniaxial pressure of 3 GPa, were subjected to isothermal heat treatment for one hour at various temperatures—ranging from 100 to 614 °C. Grain growth, solid solubility of the alloying elements, and formation of additional phases following heat treatment were investigated using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDXS). Vickers hardness was measured after heat treatment and correlated with the heat treatment temperature, composition, and microstructure. The heat treatment temperature and alloying element had a strong influence on hardness. The Influence of heat treatment on the microstructure and hardness of the alloys was dependent upon the diffusion coefficients of the alloying elements in Al. [ABSTRACT FROM AUTHOR]

Mechanical alloying was used to prepare an Ag-Cu-Sn brazing alloy with the low amounts of intermetallic compounds. X-ray diffraction and differential scanning calorimetry were carried out to investigate the phase transformation of the as-milled samples. It seemed that the intermetallic compounds experienced the stage of synthesis-decomposition-resynthesis in the ball milling process. By controlling the ball milling time and tin contents, the solid solution phases of Ag (Cu, Sn) and Ag (Cu) were achieved in the 60Ag30Cu10Sn sample after milling for 40 h. Although the intermetallic compound will be generated during the brazing process, the improvement of their distributed morphology is beneficial for the good bonding interface of the joint with stainless steel substrate. [ABSTRACT FROM AUTHOR]

The work associated with simultaneous enhancement in the hardness and toughness is filled with challenge but significance. Here, we succeeded in dealing with this question based on Group- VIB transition metals (W, Mo and Cr), and presented a universal phenomenon that highly hard yet toughened transition metal films can be obtained by doping few small atoms. Our results indicated that the introduced low-concentration (∼6 at. %) small atoms (C or B) by magnetron co-sputtering, in the doping regime, could form supersaturated solid solution and lead to significantly increased hardness (∼2 × higher), which is comparable to their ceramic compounds. Simultaneously, exceptional metallic toughness can also be obtained in this way. Dopants induced refined grains (fine-grain strengthening), lattice distortion (solid-solution strengthening), higher compressive stress and H / E ∗ (hardness/effective elasticity modulus) contribute to such surprising combination of enhanced hardness and toughness (crack resistance). This method is expected to be applicable for the transition-metal-based protective coatings. Better yet, it is featured with higher efficiency and low cost. [ABSTRACT FROM AUTHOR]

The first-principles calculations were conducted to investigate kinetic behavior of B atom at the surface of Al alloy. The cohesive energies of Al-B solid solution was calculated and the migration behaviors of Al atom surrounding with B atom and no B atom on the Al (1 0 0) and (1 1 1) surfaces were compared to investigate the structure of supersaturated Al-B solid solution and the effect of B on preferred orientation of the Al-B films. Furthermore, the local lattice distortions and elastic modulus were determined to estimate solid solubility and performance. The results indicate that the B atom was trapped in Al lattice by dynamics to form octahedral-interstitial solid solution. And the introduction of B atom led to the enhancement of Al lattice integrity, and tend to (1 1 1) preferred orientation. [ABSTRACT FROM AUTHOR]

A new type of Sm-Co supersaturated solid solution has been developed with a stabilized TbCu-type structure. The high-Co single phases were stabilized in a wide temperature range in the prepared SmCoSi ( x=0-0.9) alloys by concurrent nanostructuring and Si-doping. The significant enhancement of the coercivity and remanence of the new type supersaturated solid solution are attributed to the effective pinning of the ultrafine nanograin boundaries and the high magnetocrystalline anisotropy of the solid solution. It was proposed that the high-temperature magnetic properties of the Sm-Co supersaturated solid solution depend strongly on the phase stability. [ABSTRACT FROM AUTHOR]

In this study, a solution-treated Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt%) alloy was processed by high pressure torsion (HPT) at room temperature, with the aim of producing a material with exceptional mechanical properties. Transmission electron microscopy and X-ray diffraction line broadening analysis reveal that a nanostructured supersaturated solid solution with a mean grain size of ~ 48 nm and high dislocation density of ~ 4.7 × 10 14 m − 2 is achieved by HPT deformation. After HPT processing, the present solution-treated samples show finer grains and higher dislocation densities as compared to as-cast samples of this alloy, other solution-treated Mg-RE alloys and conventional Mg alloys deformed using similar HPT processing conditions. This could be attributed to retardation of the dislocation annihilation through enhanced solute-dislocation and/or dislocation-dislocation interactions. The higher dislocation density and nanosized grains within supersaturated solid solution cause the microhardness to increase to ~ 126 HV, which is higher than that of the as-cast Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt%) alloy processed by HPT, and is also higher than that of any conventional Mg-rich alloy deformed using HPT. [ABSTRACT FROM AUTHOR]

In this study, severe plastic deformation by high-pressure torsion is used as a fabrication method for nanocrystalline magnetic Cu–Co alloys in bulk quantities. By subsequent isothermal annealing, phase separation of the supersaturated solid solutions can be obtained. The magnetic properties of the as-processed and annealed materials have been studied systematically and correlated to the evolving nanostructures investigated in detail by transmission electron microscopy and atom probe tomography. By additional high-pressure torsion deformation at liquid nitrogen temperature the magnetic properties of the Cu 74 Co 26 alloy can be further tuned. [ABSTRACT FROM AUTHOR]

Alloying immiscible elements has great scientific and engineering significance for materials discovery and property tailoring. However, achieving alloying in bulk state remains enormous challenge due to the strong immiscibility of them. Here, for the most classic immiscible W-Cu system, a supersaturation strategy is proposed to increase the solubility between W and Cu into a previously unattainable region where nanoscale W(Cu) supersaturated solid solution (SSS) is in-situ formed in matrix. According to the direct observation of spherical-aberration transmission electron microscopy (STEM) together with atomic-resolution chemical mapping, W(Cu) SSS is a chemical-random solid solution with bcc structure, which is composed of about 20% Cu atoms randomly replacing W atoms in W lattice. The distribution of Cu elements in SSS is heterogeneous, which tends to form nanoclusters with 10 nm in size. In addition, we elucidate the effect of SSS on mechanical properties and deformation mechanisms of W-Cu nanocomposite. Achieved strength-ductility synergy originates from the mediation of dislocations and polymorphic nano-twins. This study enriches the understanding of SSS and provides a general approach to fabricating nanocomposites with excellent mechanical properties between immiscible elements. • Bulk W-Cu nanocomposites with W(Cu) supersaturated solid solution (SSS) phase were prepared via supersaturation strategy. • The structure and chemical composition of SSS were revealed at the atomic scale. SSS is a chemically disordered substitutional solid solution formed by about 20% of Cu atoms replacing W atoms in the W lattice. Cu elements are heterogeneously distributed in SSS, which tends to form nanoclusters of about 10 nm in size at the nanoscale. • The supersaturated W-Cu nanocomposites have an exceptional combination of tensile strength and ductility, and their excellent mechanical properties come from the mediation of dislocations and polymorphic nano-twins (including 9R phase). [ABSTRACT FROM AUTHOR]

Zn-Mn alloys have been recognized as promising biodegradable metals due to moderate degradation and good osteogenesis. However, the alloying content of Mn has been severely limited by the low solid solubility (0.8 wt%) in conventional preparation process to avoid the excessive formation of brittle intermetallics. In this work, supersaturated solid solution was achieved in Zn-Mn alloys via mechanical alloying (MA) and selective laser melting (SLM). During MA process, the mixed Zn and Mn powders experienced repeated welding and fracturing, which resulted in refined grains and abundant crystal defects that stored extra energy. This could reduce the energy barrier of interatomic diffusion and induce the rapid diffusion of Mn atoms, leading to supersaturated solid solution with ∼3.6 wt% Mn homogeneously dissolved in Zn lattices. Moreover, the rapid solidification process of SLM effectively maintained the metastable supersaturated structure. In addition, the Zn-15Mn alloys prepared by MA and SLM were composed of fine equiaxed grains (∼4.34 µm) and high content of high-angle grain boundaries (54.8%). Owing to solution strengthening and grain refinement, the Zn-15Mn alloy prepared by MA and SLM exhibited a compressive yield strength of 178 MPa which was 2.8 times and 1.6 times those of pure Zn and Zn-15Mn alloy without MA process, respectively, as well as a more ductile fracture. Meanwhile, the Zn-Mn alloys exhibited accelerated degradation and comparable cytocompatibility to pure Zn. These findings indicated that the combined process of MA and SLM may be an efficient strategy for the preparation of alloys characterized by supersaturated solid solution and refined grain structure. • Supersaturated solid solution was achieved in Zn-Mn alloys via MA and SLM. • The solid solubility of Mn in Zn particles was extended to 3.6 wt% by MA. • SLM process effectively maintained the metastable supersaturated structure. • The prepared Zn-15Mn alloy showed an enhanced compressive yield strength of 178 MPa. [ABSTRACT FROM AUTHOR]

AZ61 Mg and AZ61 Mg with 10 at. %Ti addition (AZ61-10 at. %Ti) were mechanically milled and a comparative study on microstructure evolution was performed. During mechanical milling, Mg grain refining/nanocrystallization and the dissolving of Mg 17 Al 12 precipitates, with the formation of Al supersaturated Mg solid solution, were observed for both materials due to mechanical milling. As analyzed by density dislocation, Ti dispersions hinder the movement of dislocations and grain boundaries and accelerate the dislocation pile-up. Therefore, Ti addition accelerated Mg grain refining, meanwhile, the ultimate Mg grain (43.47 nm) with Ti dispersions was smaller than that (69.19 nm) without Ti dispersions based on X-ray diffraction and transmission electron microscopy results. As the scanning electron microscope and X-ray diffraction exhibiting, the dissolving of Mg 17 Al 12 precipitates was expedited by Ti dispersions and the dissolving of Al in Ti phase was verified by high angle annular dark field. Moreover, during mechanical milling, Ti particulates entranced Mg particles gradually by the welding and cracking effect. After mechanical milling, Ti phase, dispersed in Mg matrix, were smashed to approximately 274.0 nm and Ti supersaturated Mg solid solution was synthesized with the solid solubility being 1.07 at. %. [ABSTRACT FROM AUTHOR]

The comparative analysis of the effect of monotonous and non-monotonous severe plastic deformations (SPD) on the structure and properties of aluminum alloys has been carried out. Conventional hydrostatic extrusion (HE) with a constant deformation direction and equal-channel angular hydroextrusion (ECAH) with an abrupt change in the deformation direction were chosen for the cases of monotonous and non-monotonous SPD, respectively. Model cast hypoeutectic Al-0.3%Sc alloys and hypereutectic Al-0.6%Sc alloys with Ta and Ti additives were chosen for studying. It was demonstrated that SPD of the alloys resulted in the segregation of the material into active and inactive zones which formed a banded structure. The active zones were shown to be bands of localized plastic deformation. The distance between zones was found to be independent of the accumulated strain degree and was in the range of 0.6-1 μm. Dynamic recrystallization in the active zones was observed using TEM. The dynamic recrystallization was accompanied by the formation of disclinations, deformation bands, low-angle, and high-angle boundaries, i.e., rotational deformation modes developed. The dynamic recrystallization was more intense during the non-monotonous deformation as compared with the monotonous one, which was confirmed by the reduction of texture degree in the materials after ECAH. [ABSTRACT FROM AUTHOR]

A Cu-37 at%Ag composite was produced by high-pressure torsion processing of elemental Cu and Ag powders at room temperature. The initial micrometer-sized powder particles were compressed directly in the high-pressure torsion tool and subsequently deformed to different strain levels. The microstructural evolution was studied in detail by scanning and transmission electron microscopy and synchrotron X-Ray measurements, and related to the mechanical properties by microhardness and nanoindentation measurements. The HPT process led to an alignment of Cu and Ag into a lamellar composite microstructure. With increasing applied strain the Cu and Ag lamellae were continuously thinned and simultaneously an ultrafine-grained microstructure was formed in the separate Cu and Ag lamellae. When the lamella spacing reached values lower than the respective grain sizes inside the lamellae, a further lamella thinning occurred causing a significant hardness increase of the composite. At lamella spacings below 50 nm deformation started to localize in 150–300 nm broad shear bands, which surprisingly exhibited no softening. Instead, the steady formation of new shear bands aided to transform the lamellar structure into a nanocrystalline equi-axed microstructure and additionally rotated the lamellar matrix towards the shear plane. This process led to an additional refinement of the alloy and a hardness increase until a constant hardness level was obtained. Combined analyses by synchrotron X-ray and transmission electron microscopy measurements revealed that, after reaching the saturation microhardness level, mechanical mixing of Cu and Ag occurred in the shear bands, which can be attributed to the enormous strains accommodated in the shear bands. Due to the localized deformation by shear bands, structural and chemical homogenization of the alloy was not achieved even at very high applied strains. The final microstructure was composed of nanocrystalline single-phase supersaturated regions embedded in a residual nano-lamellar matrix. [ABSTRACT FROM AUTHOR]

Conventionally, bulk WC and Cr 3 C 2 -based carbide compositions have been used independently of each other. However, recent investigations have begun to explore combining these carbides together within the same composite/hard metal coating system. This work explored the diversity of phases produced in the coatings from a 42 wt% WC-42 wt% Cr 3 C 2 –16 wt% Ni powder sprayed under "low", "medium" and "high" thermal input conditions using high velocity oxygen-fuel (HVOF), an argon‑helium (Ar He) plasma and an argon‑hydrogen (Ar H 2) plasma respectively. During spraying, the Ni binder melted, leading to variations in the extent of carbide dissolution and peritectic decomposition as a function of thermal input. Low thermal input, typified by the HVOF technique, led to preferential dissolution/decomposition of the Cr 3 C 2 grains into the melt, while retaining more of the higher melting point WC grains. The coating was dominated by a supersaturated Ni phase, along with the retained carbides. High thermal input, typified by the Ar H 2 plasma, was postulated to exceed the peritectic decomposition temperature of WC. The coating consisted of a supersaturated Ni alloy, along with the metastable phases WC 1-X and β-W 2 C. No metastable Cr-carbides formed in any of the coatings. The mechanism of coating phase formation is discussed. • A 42 wt% WC-42 wt% Cr 3 C 2 –16 wt% Ni powder sprayed using HVOF and Plasma spraying • Low thermal input led to preferential decomposition of the Cr 3 C 2 grains into the melt • The HVOF was dominated by a supersaturated Ni phase, along with the retained carbides • High thermal input exceeded the peritectic decomposition temperature of WC • The coating consisted of a supersaturated Ni alloy, metastable phases WC 1-X and β-W 2 C [ABSTRACT FROM AUTHOR]

The effect of Sc and Sc + Zr on the structure and properties of Al-Mg-Si alloys is studied using the methods of hardness measurement, resistivity, mechanical properties, and light and electron microscopy. A considerable strengthening of Al-MgSi alloys doped with transition metals (Sc or Sc + Zr) during natural aging and its almost complete absence during artificial aging are established. The observed effects are explained using electron microscopy and local X-ray analysis. [ABSTRACT FROM AUTHOR]

The effect of superheating of melt on structure formation in hypereutectic alloy Al - 1.2 at.% Co is studied under the conditions of rapid cooling. It is shown that any superheating of the melt yields a double-phase structure in ribbons, which is represented by an aluminum solid solution partially supersaturated with cobalt and cobalt aluminides. Annealing changes the morphology of the cobalt aluminides. The solid solution decomposes at about 350°C. [ABSTRACT FROM AUTHOR]