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The ordered γ′-(Ni, Cu)3Al is a crucial strengthening phase that improves the high-temperature resistance of Cu-based alloys, so it is important to predict the kinetic evolution of the composition and microstructure of the phase for high-temperature applications. Herein, this paper discusses the temporal evolution of the composition and coarsening of the γ′ phase in a model ternary Cu50Ni37.5Al12.5 (at%) alloy during isothermal aging at 600, 700, 800, and 900 °C for 1–36 h. It is found that the γ′ phase composition evolves linearly toward a binary γ′ phase as the aging time increases during the process of aging at 800 and 900 °C, which cannot be predicted by the ternary phase diagrams alone. Meanwhile, through the utilization of the aforementioned linear law, the γ phase composition can be predicted at a given temperature within the alloy by determining the volume fraction of the γ′ phase. Additionally, the activation energy for coarsening decreases, and the coarsening rate of the γ′ phase increases owing to the higher diffusion rate of Cu at high temperatures. The addition of microalloying elements with strong enthalpic interactions is beneficial for reinforcing the structural stability of the γ′ phase. This work provides a simple method for the compositional analysis and performance prediction of Cu–Ni–Al alloys at elevated temperatures and sheds light on the subsequent compositional design and optimization of Cu-based high-temperature alloys. [ABSTRACT FROM AUTHOR]

Microalloying is an effective method to regulate the mechanical properties of deposited metal. In this paper, ERNiMo-2 deposited metals with different Si content were prepared. The influence of Si element and thermal exposure treatment on microstructure evolution and high-temperature mechanical properties of ERNiMo-2 deposited metal was investigated. The results show that the size and distribution density of eutectic carbides increased significantly with the addition of Si while more M2C nano-sized carbide particles were observed around the eutectic carbide. Thermal exposure treatment hardly influence the size and distribution of the eutectic carbides, but significantly promote the formation of nano-sized carbide particles. The tensile results at 700 °C show that the density of precipitated carbides and the yield strength of deposited metal increased significantly with the increase of Si content. The thermal exposure would soften the deposited metal because of the obvious decrease of dislocation density and the unobvious strengthening effect from nano-sized carbide particles. The research results are significant for optimizing the composition of ERNiMo-2 welding wire and improving the mechanical performance of welded components. [ABSTRACT FROM AUTHOR]

Lightweight strategy is essential for the development of transportation vehicles and aerospace industries. As a type of lightweight material, high-strength aluminum alloys are limited to service temperatures below 200 °C due to the rapid coarsening of strengthening nano-precipitates, which cannot satisfy the increasing demands of practical applications. High-temperature applications beyond 250 °C become the bottle-neck problem of Al alloys. In this paper, we review existing literature on the improvement of high-temperature performance of aluminum alloys by stabilizing nano-precipitates. On the basis of atomic-scale microstructure regulation, several design strategies, such as interface segregation, co-precipitation, core/shell structure, and interstitial ordering, have been proposed, resulting in the development of a number of heat-resistant Al alloys for use at 300–400 °C. Moreover, the fundamental theories of solid-state phase transformation, especially precipitation aging and coarsening, are correspondingly advanced on the frontiers of science. [ABSTRACT FROM AUTHOR]

The aim of the study is to consider the features of the physico–chemical processes in the near-contact region of the semiconductor SiC phase doped with radionuclide by solid-phase diffusion of C atoms, generation of nonequilibrium carriers and the semiconductor phase distinctive characteristic features. The DFT approach in this paper is aimed at obtaining evidence of the vacancy mechanism of diffusion during the formation of the SiC phase in the Si wafer. Radionuclide and silicon atoms counter-diffuse through a growing layer of silicon carbide, forming layers by solid-phase chemical transformation of silicon of - or -type conductivity into heterostructures of anisotypic or isotypic type of conductivity relative to the SiC phase, with superstecheometric alloying with conservation of the valence and the type of impurity conductivity, forming, depending on the phase, effects energetically manifested as the effect of "the inner sun," which is the source of electrons and electron–hole pairs at ionization losses. This is due to interactions with the electrons of the shells of neighboring atoms, leading to the formation of electrons and holes in the region of spatial charge and carrying by built-in electric fields. The purpose of the study is due to an increase in the efficiency of separation of electron–hole pairs. [ABSTRACT FROM AUTHOR]

The influence of isothermal holding (IH) near the pearlite start temperature (Ps≈610 °C) and above the martensite start temperature (Ms≈245 °C) were studied in two hot-rolled (FRT≈1000 °C) high carbon steels, without (HC0) and with Nb microalloying (HC1). Optical microscopy (OM), field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) were utilised for observing the microstructural constituents whereas, nanoindentation and microindentation were performed to estimate the average hardness and elastic modulus values of various phase constituents. It has been observed that hot deformation in the austenite region results in the formation of a dual phase-type microstructure consisting of fine pearlite lamella and ferrite grains with some amount of degenerated pearlite. IH at 570 °C leads to a higher volume percentage of ferrite and coarsening of pearlite whereas, IH at 300 °C results in mixed phases comprising bainite, a very low amount of martensite/retained austenite (M/RA), pearlite and some amount of ferrite. Hot rolled microalloyed steel when isothermally held near the Ps results in a significant enhancement of ductility than hot rolled and air-cooled condition while sacrificing tensile strength marginally, which may be attributed to a higher percentage of ferrite and refinement of pearlite due to Nb addition. The estimated yield strength values correlate well with those experimental yield strength values, but a little discrepancy has been noticed for the ultimate tensile strength values. Possible interpretations are suggested in this paper. [ABSTRACT FROM AUTHOR]

In this paper, the effects of Nb contents (0.05 ~ 0.50wt%) and hot rolling temperatures (1000 ~ 1200 °C) on microstructure and mechanical properties of high-silicon electrical steel were studied. The results show that adding a small amount of Nb can significantly improve the plasticity of high-silicon electrical steel. Compared with the specimens without Nb, the three-point bending load–deflection curves of the alloys with Nb contents of 0.05 ~ 0.50wt% after warm rolling showed obvious plastic stage. The average fracture deflection increases from 4.5 to 9.9 mm with the Nb content increasing from 0.05 to 0.50wt%. When the hot rolling temperature is 1000 °C, the Nb-containing high-silicon electrical steel has a layered microstructure along the thickness direction. The surface layer is equiaxed grains with dynamic recrystallization, while the center of the thickness is a long strip structure with dynamic recovery. The mechanism of Nb microalloying to improve plasticity includes three aspects: Firstly, the layered structure hinders the propagation of cracks and delays the progress of fracture; secondly, a large number of fine Nb precipitates will hinder the grain growth and refine the grains; thirdly, the formation of the Nb-precipitated phase destroys the ordered rearrangement between adjacent Fe and Si atoms in the matrix, inhibits the ordered transformation and reduces the ordered degree of high-silicon electrical steel. When the hot rolling temperature is increased to 1100 °C or above, the layered structure disappears, the grain coarsens obviously, and the plasticity of the warm-rolled specimens is significantly reduced. [ABSTRACT FROM AUTHOR]

The modified layers were prepared on the 65Mn steel surface by pulse detonation-plasma technology (PDT) treatment. The effects of PDT on the morphology, phase structure, microhardness, and crystallographic orientation of 65Mn steel were studied. The modified layer with uniform thickness, compact structure and high hardness can be formed on the surface of 65Mn steel after PDT treatment. It was found that the grains are refined in modified layer, the residual austenite is formed with different physical processes, and the element of electrode is implanted into the surface to cause microalloying effects. Moreover, the microhardness and the wear resistance of the modified layer improve with increasing of treatment pulse. The maximum microhardness of modified layer is up to 794.9HV, and the wear resistance can be improved to be 2.1 times that of the substrate, which might due to grain refinement, dislocation increase and impact hardening. The possible mechanisms of the changes of microstructure and properties in modified layer after PDT treatment were discussed in this paper. [ABSTRACT FROM AUTHOR]

Controlling the electrochemical properties of non-metallic inclusions is of substantial interest in the design of corrosion-resistant alloys. To the best of our knowledge, the dissolution and pitting corrosion behavior of selenide inclusions in stainless steels and the improvement of the pitting corrosion resistance of type 304 stainless steels via Se microalloying have not been investigated. In this study, stainless steel specimens containing artificial MnS and MnSe inclusions were fabricated via spark plasma sintering to systematically investigate their electrochemical properties. The superior pitting corrosion resistance and dissolution resistance of MnSe to those of MnS were demonstrated. The results obtained from the sintered specimens were applied to improve the pitting corrosion resistance of type 304 stainless steels via Se microalloying. Adding a trace amount of Se (0.005 mass%) altered the readily soluble sulfide inclusions to dissolution-resistant selenide-type inclusions, resulting in improved pitting corrosion resistance of type 304 stainless steel. [ABSTRACT FROM AUTHOR]

The implementation of wire-arc directed energy deposition requires the development of novel, process-adapted, high-performance aluminum alloys. Conventional high-strength alloys are, however, difficult to process as they are prone to hot-cracking. Crossover alloys based on Al-Mg-Zn combine good processability with good mechanical properties following artificial aging. Here, we present an effort to further improve the mechanical properties of Al-Mg-Zn crossover alloys using Ag microalloying. No cracks and few porosities were observed in the samples. The microstructure is dominated by fine and globular grains with a grain size ≈ 26.6 µm. The grain structure is essentially free of texture and contains fine microsegregation zones with ≈ 3–5 µm thickness of segregation seams. Upon heat treatment these microsegregation zones are dissolved and T-phase precipitates are formed as clarified by diffraction experiments. This precipitation reaction results in a microhardness of ≈ 155 HV0.1, a yield strength of 391.3 MPa and 418.6 MPa, an ultimate tensile strength of 452.7 MPa and 529.4 MPa and a fracture strain of 3.4% and 4.4% in transversal and in longitudinal directions, respectively. The gained results suggest that highly loaded structures can be manufactured by wire-arc directed energy deposition using the newly developed aluminum crossover alloy. [ABSTRACT FROM AUTHOR]

Mg-Zn-Zr wrought alloys have been widely developed for lightweight applications. Zr microalloying contributes to remarkable grain refinement during solidification and bimodal microstructure via forging. To obtain an optimum Zr content for a balance between cost and mechanical property, it is necessary to understand the influence of varied Zr addition levels on the microstructure and mechanical property of the final forged product. In the present study, two levels of Zr addition (nominally 0.40 wt.% and 0.60 wt.%) were added to a Mg-3 wt.% Zn alloy to investigate the effect of varied Zr contents on the microstructures under as-cast, as-forged and tensile-strained conditions, as well as the uniaxial tensile properties of the as-forged alloy. The as-forged microstructures comprise fine dynamic recrystallized (DRXed) grains and coarse deformed (unDRXed) domains, which become more refined with the Zr content increasing from ~ 0.43 wt.% to ~ 0.67 wt.%. The microstructural change caused by the increased Zr addition has minor impact on 0.2% proof stress but remarkably improves both uniform and post-uniform elongations, for which the underlying mechanisms have been discussed. [ABSTRACT FROM AUTHOR]

In this research, the structural state and mechanical properties of nine pilot batches of HC340LA cold-rolled steel, annealed in bell-type furnaces from the steel of two melts of different compositions using Nb or Ti microalloying, were studied. From the obtained results, the uniformity and stability of the structure and properties of rolled products were significantly improved both in each pilot batch and in the transition from batch to batch compared with those of mass-produced cold-rolled steel grade HC340LA while reducing costs. Methods for further improving the efficiency of the integrated technology for the production of HC340LA rolled products according to EN 10268 were determined. [ABSTRACT FROM AUTHOR]

The effect of Ti and Ce microalloying on the mechanical properties of Al-9Si-3.5Cu-0.2Zr-0.1Sr cast aluminum alloy was investigated, and it was hoped that the cast aluminum alloy with excellent comprehensive properties could be obtained. On the basis of Zr-Sr microalloyed cast aluminum alloy (Al-9Si-3.5Cu-0.2Zr-0.1Sr), the effects of 0.2Zr-0.1Sr-0.16Ti ternary microalloying and 0.2Zr-0.1Sr-0.16Ti-0.1Ce quaternary microalloying on the microstructure and properties of the alloy were investigated. The experimental results show that compared with Zr-Sr microalloying, Zr-Sr-Ti microalloying and Zr-Sr-Ti-Ce microalloying can effectively refine the microstructure, improve the modification effect of Si phase, and promote the improvement of Al2Cu phase, thus improving the properties. The higher the degree of microalloying, the hardness is gradually increasing, but the electrical conductivity is gradually decreasing. Zr-Sr-Ti microalloying can increase the tensile strength of the alloy to 400.07 MPa and the elongation to 9.5%. Zr-Sr-Ti-Ce microalloying do not continue to improve the properties of the alloy, and the tensile strength and elongation after fracture decrease to a certain extent due to the addition of Ce. Therefore, the best comprehensive properties can be obtained by Zr-Sr-Ti microalloying (Al-9Si-3.5Cu-0.2Zr-0.1Sr-0.16Ti). [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of a novel Cr and Si co-alloying Fe–0.6C–15Mn steels, labeled as 2Cr(3Si), 4Cr(3Si), 6Cr(3Si), and 4Cr(0Si), were investigated. All samples for mechanical property test and microstructure analysis were subjected to solution treatment at 1100 °C for 1 h after forging. The results indicate that the microstructure for the 2Cr(3Si), 4Cr(3Si) and 4Cr(0Si) steels mainly consists of the full austenite, and grain size is about 100 μm, whereas the microstructure of the 6Cr(3Si) steel exhibits austenite and some undissolved Cr7C3 carbides. The refined austenite grain size of 48 μm is obtained in 6Cr(3Si) steel. The strength and elongation of the experiment steels with Si and Cr increase significantly with the Cr contents. Among the steels, the 6Cr(3Si) steel has the maximum yield strength, tensile strength and elongation of 490 MPa, 987 MPa and 41.5%, respectively. And the impact toughness is 151 J cm−2. The Si-free steel (4Cr(0Si)) exhibits a low yield strength (372 MPa) and a high tensile strength (992 MPa). The high elongation of 74.8% and impact toughness of 320 J cm−2 are obtained. The results also demonstrate that the Cr and Si co-alloying in high-Mn steels is beneficial to improve work hardening capability, and the work hardening capability increases with the increase of Cr content. According to the results analyzed by the electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), the strain-induced ε-martensite is dominant at the low strain level and the content of ε-martensite increases with the increase of the tensile strain. The maximum amount of the ε-martensite is found in the 6Cr(3Si) steel. With the strain increasing, α'-martensite appears in microstructure, which is formed on the ε-martensite. In addition, the stacking faults (SF) and mechanical twins (MT) are also observed. [ABSTRACT FROM AUTHOR]

The occurrence of anomalous particles (granules) with significantly different contents of interstitial microalloying elements, that is, carbon and boron, is an important feature of the homogeneity of the composition of rapidly quenched powders of stainless steels and high temperature Ni-based superalloys produced by the PREP method. A multi-scale experimental study of the evolution of the structure of PM HIP stainless steels under heat treatment and hot deformation has been carried out. Direct nuclear methods of activation autoradiography on carbon, track autoradiography on boron, metallography, SEM, EDX, and OIM have been used to reveal the evolution of the microstructure of PM HIP stainless steels. A significant effect of heat treatment and hot deformation on the behavior of carbon and boron in PM HIP stainless steels has been revealed. A significant effect of the microstructure evolution and the behavior of carbon and boron on the mechanical properties of PM HIP stainless steels in comparison with those of their traditional counterparts has been discovered and discussed. [ABSTRACT FROM AUTHOR]

Tensile creep experiments and pulse-echo overlap (PEO) method were utilized to analyze the impact of small additions of 2.5%wt In, Fe and Co (0.1%wt for each) on the creep resistance and elastic properties of a cast Sn-7Zn alloy. The In-modified alloy displays noticeably enhanced creep resistance and increased the fracture time (~ 2.7 times) due to precipitation strengthening and formation of γ-InSn4 particles. The In-modified alloy exhibits an as-solidified grain structure, which is finer than the Sn-7Zn alloy, and predicted to enhance deformation resistance by lattice self-diffusion creep. Nonetheless, the creep resistance of Sn-7Zn alloy deteriorates after Fe and Co addition, highlighting the excellent coarsening of the new γ-Zn21Co5, γ-Co2Sn2Zn, and α-Fe0.92Sn0.08 precipitates. The obtained results implied that the creep strain rate follows the Garofalo hyperbolic sine equation, and the computed creep stress exponent is consistent with a climb-controlled dislocation creep. Consequently, for all PEO tests, the values of resulting Young's modulus (E) (66.7 GPa) and shear modulus (G) (20.5 GPa) of In-modified Sn-7Zn alloy were superior to those of the conventional plain Sn-7Zn alloy and Fe and Co modified alloy in its cast condition. [ABSTRACT FROM AUTHOR]

Mo-rich precipitation in super-austenitic stainless steels has significant effects on their hot workability and corrosion resistance. The occupation tendencies of Mo and other alloying elements at Σ3(112), Σ5(210), and Σ9(114) grain boundaries of fcc-Fe were calculated through the first-principles method, and the influence of B and Ce on the grain boundary segregation of alloying elements was analyzed. Then, microscopic mechanism for the precipitation in super-austenitic stainless steels containing B and B + Ce was also discussed. The results show that the segregation tendencies of Cr and Ni to grain boundaries are extremely weak, while those of Mo and Ce are materially stronger, and they are apt to segregate at Σ5(210) and Σ9(114) grain boundaries. Mo, in particular, exhibits a wider segregation area and tends to segregate to the whole grain boundary regions. However, after being located at grain boundaries, B and B + Ce make the segregation of Mo at these grain boundaries more difficult, which is beneficial to adjusting the grain boundary segregation of Mo. Moreover, the calculated results agree well with the experimental results. Through microstructure characterization, the micro-alloying of B and B + Ce can indeed inhibit the Mo-rich precipitation in super-austenitic stainless steels, especially for B + Ce, reducing a great number of large precipitates along grain boundaries to discontinuous and finer precipitates. [ABSTRACT FROM AUTHOR]

Results of transmission electron microscopy of the thin structure of coiled steel alloyed with Cr‒Nb, Cr–Nb–V–Ti, Nb–V–Ti, Nb–V, Nb, V–N, manufactured on casting and rolling line at AO Vyksunskii Metallurgicheskii Zavod are presented. Results of laboratory corrosion tests in aqueous solutions with different mineralization levels, imitating real oil media met in oil deposits in Russia, are compared; formation peculiarities of the thin structure of metal prepared using the mentioned alloying systems are studied. Presence of carbonitrides of microalloying elements, formed in austenite, was found to have no effect on the corrosion resistance of pipe steels. At the same time, carbonitrides of the interphase or mixed type and formed in ferrite impair the corrosion resistance of metal significantly; vanadium carbonitrides were found to be the most deleterious. [ABSTRACT FROM AUTHOR]

Medium-Mn automotive sheet steels require optimized heat-treatment processes to obtain benefits caused by strain-induced martensitic transformation of retained austenite (RA) during sheet metal forming or crash events. The intercritical annealing (IA) approach at different temperatures in a range of 640 °C to 800 °C is proposed in the study for a 5Mn hot-rolled medium-Mn sheet steel. The experiments were performed in terms of dilatometry. The analysis of the cooling curves allowed development of a new method for calculating the high-temperature phase equilibrium. The calculations were validated by modeling with JMatPro and experimentally verified by X-ray diffraction (XRD). The microstructure evolution was characterized using light optical microscopy and scanning electron microscopy (SEM), including electron backscatter diffraction (EBSD). The quantitative determination of the fraction, morphology, chemical composition, and stability of the RA was done. Mechanical properties were determined by hardness measurements. The research showed a substantial influence of the IA temperature on the RA fraction and chemical stability and properties of medium-Mn Al-alloyed steel. At temperatures of 680 °C and 700 °C, the largest fraction of over 35 pct of stable RA was obtained, which does not transform to martensite during cooling. [ABSTRACT FROM AUTHOR]

Particle number densities are a crucial parameter in the microstructure engineering of microalloyed steels. We introduce a new method to determine nanoscale precipitate number densities of macroscopic samples that is based on the matrix dissolution technique (MDT) and combine it with atom probe tomography (APT). APT counts precipitates in microscopic samples of niobium and niobium-titanium microalloyed steels. The new method uses MDT combined with analytical ultracentrifugation (AUC) of extracted precipitates, inductively coupled plasma–optical emission spectrometry, and APT. We compare the precipitate number density ranges from APT of 137.81 to 193.56 × 1021 m−3 for the niobium steel and 104.90 to 129.62 × 1021 m−3 for the niobium-titanium steel to the values from MDT of 2.08 × 1021 m−3 and 2.48 × 1021 m−3. We find that systematic errors due to undesired particle loss during extraction and statistical uncertainties due to the small APT volumes explain the differences. The size ranges of precipitates that can be detected via APT and AUC are investigated by comparison of the obtained precipitate size distributions with transmission electron microscopy analyses of carbon extraction replicas. The methods provide overlapping resulting ranges. MDT probes very large numbers of small particles but is limited by errors due to particle etching, while APT can detect particles with diameters below 10 nm but is limited by small-number statistics. The combination of APT and MDT provides comprehensive data which allows for an improved understanding of the interrelation between thermo-mechanical controlled processing parameters, precipitate number densities, and resulting mechanical-technological material properties. [ABSTRACT FROM AUTHOR]

Features of thermo-mechanical rolling in various types of rolling mills are studied: plate mill (continuous, semicontinuous), Steckel mill, and a casting and rolling complex with a continuous broad strip mill. Limitations are considered for each type of mill due to the dimensional range, composition and location of equipment, size and composition of an original workpiece, and the possibility of manufacturing product with a good set of high strength, ductility, and cold resistance. It is shown that implementation of thermomechanical rolling taking into account features of the production scheme and understanding structure formation processes manufacture of cold-resistant rolled product is possible in all of types of the mills considered. Use of contemporary and precise structure formation models may reduce the effect of limitations with the exception of physical features, and expand the possibilities of rolled product structure and property formation [ABSTRACT FROM AUTHOR]

The structural state and mechanical properties of cold-rolled steel of strength class 340 MPa or grade HC340LA of the current production, annealed in bell-type furnaces, were examined on the metals of eight industrial melts. The results demonstrate the expediencies of using an economical alloying and microalloying system and optimizing the technologies for smelting, hot and cold rolling, and recrystallization annealing of steel. [ABSTRACT FROM AUTHOR]

Low-temperature decomposition of supersaturated solid solution into unfavorable intergranular precipitates is a long-standing bottleneck limiting the practical applications of nanograined aluminum alloys that are prepared by severe plastic deformation. Minimizing the vacancy concentration is generally regarded as an effective approach in suppressing the decomposition process. Here we report a counterintuitive strategy to stabilize supersaturated solid solution in nanograined Al-Cu alloys via high-density vacancies in combination with Sc microalloying. By generating a two orders of magnitude higher concentration of vacancies bonded in strong (Cu, Sc, vacancy)-rich atomic complexes, a high thermal stability is achieved in an Al-Cu-Sc alloy that precipitation is nearly suppressed up to ~230 °C. The solute-vacancy complexes also enable the nanograined Al-Cu alloys with higher strength, greater strain hardening capability and ductility. These findings provide perspectives towards the great potentials of solute-vacancy interaction and the development of nanograined alloys with high stability and well-performed mechanical properties. Low-temperature decomposition and insufficient plastic deformability are bottlenecks that limit the practical applications of nanograined Al alloys. Here the authors utilize a high density vacancies in combination with Sc microalloying to stabilize nanograined Al-Cu alloys. [ABSTRACT FROM AUTHOR]

In this work, multipass torsion tests followed by coiling simulations under different conditions have been performed with a reference Nb (0.03 pct) and a high Ti (0.1 pct)–Nb-microalloyed (0.03 pct) steel. In the case of the high Ti steel, estimated yield strengths close to or over 700 MPa were obtained for some of the conditions researched. However, a very significant effect of previous austenite grain size and strain accumulation on precipitation strengthening has also been observed. As a result, depending on deformation sequence and final cooling conditions, the coiling simulation temperatures that lead to the highest mechanical strength varied from 600 °C to 500 °C. The effect of increasing strain accumulation was mainly related to higher phase transformation temperatures, which led to a lower driving force for precipitation and higher microalloying element diffusivity, resulting in the formation of less and coarser precipitates. [ABSTRACT FROM AUTHOR]

The geometric structure, binding energy and electronic properties of PbnInn (n = 2–10) alloy clusters were studied by using density functional theory, and the stability of lead-indium clusters were discussed. Ab initio molecular dynamics were performed to exhaust search the global minimum structures of the clusters on the level of GGA-HCTH by DMol3 package. The structures were optimized and further calculated the binding energy, vertical ionization potentials, the vertical electron affinities, HOMO–LUMO gap and NBO on the level of B3LYP/SDD by using Gaussian program. The results show that as the size increases, the binding energy increases, the structure tends to be spherical, and In gradually occupies the center of the structure and has the tendency of small pieces gathering. Combined with our calculated results, we can not only explain the cause of Pb enrichment in the field of metal extraction, but also clarify the effect of In on Pb grain refinement. [ABSTRACT FROM AUTHOR]

Understanding glass formation behaviors of Ti-based metallic glasses (MGs) which contain only nontoxic elements is of great importance not only to unveiling the glass formation mechanism in MGs but also to the application of MGs as biomaterials. In this work, to examine the effects of microalloying on glass formation in toxic-element-free TiZrSi-based MGs, both isothermal and non-isothermal crystallization behaviors of Ti42Zr40Si15Ta3, Ti42Zr40Si15Sn3, and Ti42Zr40Si10Sn3Ge5 MGs are characterized. The Avrami exponents n obtained from isothermal crystallization processes for Ti42Zr40Si15Ta3, Ti42Zr40Si15Sn3, and Ti42Zr40Si10Sn3Ge5 MGs are 2.54 ~ 2.90, 2.72 ~ 3.19, and 2.80 ~ 3.35, respectively. The isothermal crystallization activation energies E c 1 for Ti42Zr40Si15Ta3, Ti42Zr40Si15Sn3, and Ti42Zr40Si10Sn3Ge5 MGs are also derived as 259.89 ± 19.45 kJ/mol, 262.39 ± 15.80 kJ/mol, and 359.25 ± 17.21 kJ/mol, respectively. The non-isothermal crystallization activation energies E c 2 obtained from continuous heating tests for Ti42Zr40Si15Ta3, Ti42Zr40Si15Sn3, and Ti42Zr40Si10Sn3Ge5 MGs are estimated as 535.84 ± 27.35 kJ/mol, 660.46 ± 42.15 kJ/mol, and 473.65 ± 48.04 kJ/mol, respectively. Based on the crystallization activation energies and the Avrami exponents, the isothermal crystallization kinetics of all the 3 TiZrSi-based MGs are inferred to be interface-controlled crystal growth with negligible nucleation rate. As to the non-isothermal crystallization kinetics, it is found that the substitution of Ta by Sn does not alter much the contributions of nucleation and growth in crystallization and that the substitution of Si by Ge in the Ti42Zr40Si10Sn3Ge5 MG significantly reduces the contribution of nucleation. These results would help to advance current knowledge on glass formation in TiZrSi-based MGs. [ABSTRACT FROM AUTHOR]

In this study, the effect of vanadium addition (0.14 wt pct) on microstructure and hydrogen embrittlement (HE) susceptibility were investigated in 1300 MPa strength level bolt steel, and hydrogen trapping and diffusion were analyzed by hydrogen permeation and thermal desorption spectroscopy (TDS). The results showed that the addition of 0.14 wt pct V in the bolt steel can significantly improve the HE resistance. The vanadium addition can form a large number of V precipitates. Compared with the V-free bolt steel with the same strength, the vanadium addition steel possessed more significant precipitation strengthening and lower dislocation density, which was the main reason to reduce the HE susceptibility. In addition, the vanadium precipitates can provide a lot of hydrogen traps and refine the grains, resulting in the uniform distribution of hydrogen and the reduction of hydrogen accumulated at local grain boundaries, which was helpful to inhibit the hydrogen induced cracking (HIC). [ABSTRACT FROM AUTHOR]

The effect of up to 0.18% microadditions of titanium on the structure and mechanical properties of sheet low-carbon (0.07 – 0.09% C) steels with different alloying systems (C – Mn – Ti, C – Mn – V – Ti,C – Mn – Nb – Ti) is studied. The phase composition and the structure of the steels are determined. The specimens are tested for static tension and impact toughness. The content of titanium Ticr above which fine particles of TiC carbide precipitate in the structure and elevate the strength properties at simultaneous decrease in the ductility and toughness of the steels is determined. [ABSTRACT FROM AUTHOR]

In the present work, hot-rolled V and V-Ti microalloyed steels are comparatively investigated by multi-scale characterizations and electrolytically extracted phase analysis, aiming at quantitatively revealing the influence of microalloying elements on microstructure, precipitation behavior and mechanical properties. The results demonstrate that the substitution of trace Ti slightly refines and homogenizes the ferrite grain size (10.8 → 12.8 μm), but aggravates the banded structure and decreases the precipitation ratio of V (39 → 30%). Simultaneously, Ti induces the compound precipitation of V-Ti carbonitrides, which reduces the amount of V in austenite, resulting in substantially reduced precipitation strengthening due to the smaller volume fraction (0.0058 → 0.0027%), the larger particle size (34.1 → 65.8 nm) and inter-particle spacing (74 → 127 nm) of fine nano-precipitates in ferrite. The yield strength predicted by semi-empirical models agrees well with the results of tensile testing, which indicates that microcrystalline Ti substitution for V reduces the yield strength of traditional hot-rolled steel. [ABSTRACT FROM AUTHOR]

The effects of iron, copper, and niobium alloying additions on crystallization, phase transformation, and magnetic properties of Mn–Si–B-based amorphous ribbons were studied by X-ray diffraction (XRD), differential scanning calorimeter (DSC), and physical property measurement system (PPMS). The DSC results show that Mn78Si13B9 amorphous sample presents one-stage crystallization reaction. When added the alloying elements of iron, copper, and niobium into Mn–Si–B alloy system, the alloys still exhibit one-stage crystallization behaviors, but the crystallization temperature (Tx) has changed. The alloying addition of iron in Mn–Si–B alloy makes a decrease in Tx, while making further microalloying additions of copper and niobium in Mn–Fe–Si–B alloy the Tx of the alloy elevates significantly. For Mn78Si13B9, Mn68Fe10Si13B9, and Mn64Fe10Si13B9Cu1Nb3 alloys, the crystallization of amorphous phase simultaneously forms α-Mn(Si), Mn6Si, and Mn2B phases upon heating above the glass transition temperature. Besides, the thermal-magnetization M(T) curves confirm that the amorphous Mn78Si13B9 and Mn68Fe10Si13B9 samples exhibit a characteristic spin-glass behavior. The spin-glass freezing temperatures of them are about 20 ~ 22 K. [ABSTRACT FROM AUTHOR]