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Faced with the rapid development of large-scale pumped-storage power stations, the trade-off between the strength and toughness of hydropower steels in extreme environments has been limiting their application. The effects of Nb micro-alloying and direct quenching and tempering processes on the strengthening–toughening mechanism of 1000 MPa grade high-strength hydropower steel are studied in this paper, and the precipitation behavior of Nb is discussed. The results showed that only the 0.025Nb steel using the DQT process achieved a cryogenic impact energy of more than 100 J at −60 °C. Under the DQT process, a large number of deformation bands and dislocations were retained, refining the prior austenite grains and providing more nucleation sites for the precipitation of NbC during the cooling process. The DQT process has a more obvious local strain concentration, mainly focusing on the refined lath boundary, which indicates that the refinement of the microstructure also promotes the stacking of dislocations. The improvement in fine grain strengthening and dislocation strengthening by the DQT process jointly led to an increase in strength, resulting in a better combination of strength and toughness. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to investigate the effect of chemical nickel plating and mechanical alloying on the mechanical and tribological properties of FeS/iron-based self-lubricating materials as well as the wear mechanism of the materials. Design/methodology/approach: Surface modification of FeS powder was carried out by chemical nickel plating method and mechanical alloying of mixed powder by ball milling. The mechanical properties of the material were tested by tribological testing by M-200 ring block type friction and wear tester. Optical microscope was used to observe the surface morphology of the material and the transfer film on the surface of the mate parts, and scanning electron microscope and EDS were used to characterize the wear surface. Findings: Mechanical alloying ball milling was carried out so that the lubricating particles in the matrix are uniformly dispersed; nickel-plated layer enhances the interfacial bonding of FeS and the matrix, and the combination of the two improves the mechanical properties of the material, and at the same time the friction side of the surface of the lubrication of FeS lubricant transfer film formed is denser and more intact, and the friction coefficient of friction side and the wear rate of the material have been greatly reduced. Originality/value: This work aims to improve the mechanical and tribological properties of FeS/iron-based self-lubricating materials and to provide a reference for the preparation of materials with excellent overall properties. [ABSTRACT FROM AUTHOR]

Cu–15Ni–8Sn alloy is the best choice to replace beryllium bronze alloy. This alloy has unparalleled application value in aerospace, ocean engineering, electronic information, equipment manufacturing, and other fields. However, the application of Cu–15Ni–8Sn alloy is challenged and limited because of a series of problems in its preparation and processing, such as easy segregation, difficult deformation, and discontinuous precipitation. It is an effective way to improve the comprehensive properties of Cu–15Ni–8Sn alloy using alloying design and process optimization to control the as-cast, deformed, and heat-treated microstructures. At present, it is a hot spot for scholars to study. In this paper, the grade generation, system evolution, and preparation technology development of Cu–15Ni–8Sn alloy are comprehensively reviewed. The phase transformation sequence of the Cu–15Ni–8Sn alloy is discussed. The influence of the type, amount, and existing form of alloying elements on the strength of Cu–15Ni–8Sn alloy and its mechanism are systematically summarized. Furthermore, the latest research progress on the effects of solid solution, cold deformation, and aging on the phase structure transformation and mechanical properties of Cu–15Ni–8Sn alloy is summarized. Finally, the future development trend of the Cu–15Ni–8Sn alloy is projected. The research results of this paper can provide a reference for the control of the microstructure and properties of high-performance Cu–15Ni–8Sn alloys used in key fields, as well as the optimization of the preparation process and alloy composition. [ABSTRACT FROM AUTHOR]

The paper deals with the effect of the morphology characteristics, grain size, and the volume fraction of AlN- and NbC-precipitated particles on the prior austenite grain growth behavior in the Al- and Nb-microalloying 20MnCr gear steel during pseudo-carburizing heat treatments. The results indicate that the Nb addition in 20MnCr gear steel have a better effect on preventing austenite grain growth. The coarsening time after pseudo-carburizing in the Nb-microalloyed 20MnCr steel are improved by about 4 h compared with the Al-microalloyed steel. The precipitated particles coarsen and the number decreases with the pseudo-carburization temperature increasing, resulting in a reduction in the pinning pressure of the precipitated particles on the austenite grain boundaries. When the pseudo-carburization temperature reaches 1150 °C, the precipitated particles no longer have the ability to pin the austenite grain boundaries. In addition, the kinetics model for austenite grain growth under the process of the pinning and coarsening of the precipitated particles was established. [ABSTRACT FROM AUTHOR]

In high-speed steel, carbides are essential phase constituents, which have a direct impact on engineering performance and qualities of high-speed steel. The formation, morphology, and distribution of carbides are dictated by alloying elements. In this paper, various types of carbides in high-speed steel are presented. The effects of different alloying elements such as C, W, Mo, Cr, and V on the formation of carbides in high-speed steel are discussed. Research progresses on carbide improvement by microalloying elements such as N, B, Mg, and rare earth (RE) elements are reviewed. It is reported that Cr promotes the precipitation of M2C, N enhances the formation of fibrous M2C, Mg effectively shatters the large-size carbide grid, Nb refines granular carbide MC, and rare earth elements encourage the formation of M6C, resulting in irregular M2C lamellae. The incorporation of microalloying elements improves the distribution and size of carbides and also refines the solidification structure of high-speed steel. [ABSTRACT FROM AUTHOR]

Scandium is the best alloying element to improve the mechanical properties of industrial Al-Si-Mg casting alloys. Most literature reports devote to exploring/designing optimal Sc additions in different commercial Al-Si-Mg casting alloys with well-defined compositions. However, no attempt to optimize the contents of Si, Mg, and Sc has been made due to the great challenge of simultaneous screening in high-dimensional composition space with limited experimental data. In this paper, a novel alloy design strategy was proposed and successfully applied to accelerate the discovery of hypoeutectic Al-Si-Mg-Sc casting alloys over high-dimensional composition space. Firstly, high-throughput CALculation of PHAse Diagrams (CALPHAD) solidification simulations of ocean of hypoeutectic Al-Si-Mg-Sc casting alloys over a wide composition range were performed to establish the quantitative relation 'composition-process-microstructure'. Secondly, the relation 'microstructure-mechanical properties' of Al-Si-Mg-Sc hypoeutectic casting alloys was acquired using the active learning technique supported by key experiments designed by CALPHAD and Bayesian optimization samplings. After a benchmark in A356-xSc alloys, such a strategy was utilized to design the high-performance hypoeutectic Al-xSi-yMg alloys with optimal Sc additions that were later experimentally validated. Finally, the present strategy was successfully extended to screen the optimal contents of Si, Mg, and Sc over high-dimensional hypoeutectic Al-xSi-yMg-zSc composition space. It is anticipated that the proposed strategy integrating active learning with high-throughput CALPHAD simulations and key experiments should be generally applicable to the efficient design of high-performance multi-component materials over high-dimensional composition space. [ABSTRACT FROM AUTHOR]

A novel Al-Cu-Zr alloy is designed in this paper, which provides a method for further improving the strength of Al-Cu alloys. In this paper, the addition of the micro-alloying element Zr in Al-Cu alloy was studied. The effect of aging treatment on the mechanical properties and precipitation behavior of the alloy was studied. With the addition of Zr, Al3Zr phases were formed in the alloy, which acts as obstacles to dislocation motion. In addition, Al3Zr phases can be used as the nucleation site of θ′ phases to promote precipitation. All this can improve the strength of Al-Cu alloys. After one-step aging, corresponding to the highest hardness, the largest amount of θ′ phases were observed in the alloy matrix. By contrast, after two-step aging, the θ′ phases were finer, and a large amount of Guinier–Preston (GP) zones formed during the pre-aging step, which were transformed into denser and finer θ′ phases in the secondary aging step. After the same solution treatment (540 °C/12 h), undergoing 120 °C/4 h + 175 °C/10 h two-step aging, the ultimate tensile strength, yield strength, and elongation of the Al-Cu-Zr alloy were 398.7 MPa, 313.3 MPa, and 7.9%, respectively. [ABSTRACT FROM AUTHOR]

The application of low carbon micro-alloyed steel sheets in chassis and frame parts of automobiles demands high formability during hot or cold forming operations to produce various intricate shapes. In view of the forming applications, stretch flangeability is considered as one of the most important critical parameters for these steel grades. The stretch-flangeability of micro-alloyed steels, with three different types of microstructure consisting of mainly single-phase ferrite, ferrite-pearlite and ferrite-bainite micro-constituents, is evaluated in this investigation based on hole expansion ratio (HER). The desired microstructures of the low carbon steels micro-alloyed with Nb, Nb-V and Nb-V-Ti steels were obtained at three different coiling temperatures by systematically varying the plant operating process parameters. While Micro-alloying elements largely affect the mechanical strength and ductility of the steel, its direct impact on HER value and fracture behavior are not correlated. The correlation of microstructure with tensile strength and ductility have been attempted for the studied low carbon micro-alloyed steels and described in this paper. It is observed that single-phase steel consisting of soft ferritic matrix as well as steel with 5 to 15 pct pearlite uniformly distributed in ferrite matrix has better stretch flangeability and strength to hole expansion ratio correlation in comparison to ferrite-bainite steel. [ABSTRACT FROM AUTHOR]

The casting of metal alloys followed by hot forging is a widely used manufacturing technology to produce a homogeneous microstructure. The combination of mechanical and thermal energy envisages the microstructural properties of metal alloys. In the present investigation, a metal alloy of composition 0.05C-1.52Cu-1.51Mn (in weight %) was cast in an induction furnace using a zirconia crucible. The melt pool was monitored using optical emission spectroscopy (OES) to maintain the desired composition. The as-cast block was then subjected to forging under a pneumatic hammer of 0.5 t capacity so that any casting defects were eliminated. The as-cast block was reheated to a temperature of 1050 °C and held at that temperature for 6 h to homogenize, followed by hammering with a 50% strain using a pneumatic hammer. The microhardness was calculated using a Vickers microhardness testing apparatus. The microstructure characterization of the processed alloy was carried out using an optical microscope, electron backscattered diffraction (EBSD), energy-dispersive X-ray spectroscopy (EDXA), and a transmission electron microscope (TEM). The sample for optical microscopy was cut using a diamond cutter grinding machine and surface polishing was carried out using emery paper. Further, mechanical polishing was performed to prepare the samples for EBSD using a TEGRAPOL polishing machine. The EBSD apparatus was operated at a 20 kV accelerating voltage, 25 mm from the gun, and with a 60 µ aperture size. HKL Technology Channel 5 Software was used for the post-processing of EBSD maps. The procedure of standard polishing for OES and TEM sample preparation was followed. Recrystallization envisages equiaxed grain formation in hot forging; hence, the strain-free grains were observed in the strained matrix. The lower distribution of recrystallized grains indicated that the driving force for recrystallization was not abundant enough to generate a fully recrystallized microstructure. The fractional distribution of the misorientation angle between 15 and 60° confirms the formation of grain boundaries (having a misorientation angle greater than 15°) and dislocations/subgrain/substructures (having a misorientation angle less than 15°). The fraction of misorientation angle distribution was higher between the angles 0.5 and 6.5°; afterwards, it decreased for higher angles. The substructure was observed in the vicinity of grain boundaries. The softening process released certain strains, but still, the dislocation was observed to be deposited mostly in the vicinity of grain boundaries and at the grain interior. The fine precipitates of the microalloying element copper were observed in the range of size in nanometers. However, the densities of these precipitates were limited and most of these precipitates were deposited at the grain interior. The microhardness of 210.8 Hv and mean subgrain size of 1.61 µ were observed the enhanced microhardness was due to the limited recrystallized grains and accumulation of dislocations/subgrain/substructures. [ABSTRACT FROM AUTHOR]

Purpose: High-strength martensitic steels having strong hydrogen embrittlement (HE) susceptibility and the metal carbide (MC) nanoprecipitates of microalloying elements such as Nb, V, Ti and Mo in the steel matrix can effectively improve the HE resistance of steels. This paper aims to review the effect of MC nanoprecipitates on the HE resistance of high-strength martensitic steels. Design/methodology/approach: In this paper, the effects of MC nanoprecipitates on the HE resistance of high-strength martensitic steels are systematically described in terms of the types of MC nanoprecipitates, the influencing factors, along with numerical simulations. Findings: The MC nanoprecipitates, which are fine and semicoherent with the matrix, effectively improve the HE resistance of steel through the hydrogen trapping effects and microstructure optimization, but its effect on the HE resistance of steel is controlled by its size, number and distribution state. Originality/value: This paper summarizes the effects and mechanisms of MC nanoprecipitates on HE performance of high-strength martensitic steel and provides the theoretical basis for corrosion engineers to design high-strength martensitic steels with excellent HE resistance and improve production processes. [ABSTRACT FROM AUTHOR]

The extremely thin diameter of steel tire cord wire and steel saw wire are about 80 and 50 μm, respectively. It is supposed that this kind of ultrafine steel wire is easy to break due to large and hard nonmetallic inclusions in the steel during the drawing and standing process. This paper reviews the research advances on inclusion and microalloying elements control in tire cord steel and saw wire steel in the past 20 years. Including: 1) calculation of thermodynamics of inclusion formation in quaternary system; 2) effects of alkali metal alloys and its oxides on inclusions; 3) control of Ti‐containing inclusion and SiO2‐MnO‐Al2O3 inclusion; 4) effect of rare earth on inclusions in saw wire steel; 5) the behavior of inclusions at the solidification front of liquid steel; 6) the effect of inclusion size and morphology on the fracture behavior of steel wire; 7) ultrasonic technology was used to remove inclusions in cord steel; 8) the effect of C, Cr, Co, Ce and V on microstructure and properties of tire cord steel and saw wire steel. Finally, this paper summarizes twelve key problems that should be studied in the next decade to provide reference for metallurgical workers. [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]

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]

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]

In this paper, the progress of the test methods and characterization approaches of aluminum alloys hardenability was reviewed in detail. The test method mainly included the traditional end-quenching method and the modified method. While the characterization approaches of alloy hardenability consist mainly of ageing hardness curves, solid solution conductivity curves, ageing tensile curves, time temperature transformation (TTT) curves, time temperature properties (TTP) curves, continuous cooling transformation (CCT) curves, and advanced theoretical derivation method have appeared in recent years. The hardenability testing equipment for different tested samples with different material natures, engineering applications properties, and measurement sizes was introduced. Meanwhile, the improvement programmed proposed for shortcomings in the traditional hardenability testing process and the current deficiencies during the overall hardenability testing process were also presented. In addition, the influence factors from the view of composition design applied to the hardenability behaviors of Aluminum alloys were summarized. Among them, the combined addition of micro-alloying elements is considered to be a better method for improving the hardenability of high-strength aluminum alloys. [ABSTRACT FROM AUTHOR]

In recent decades, the effect of Fe element addition on titanium alloy has been investigated extensively due to the development of low-cost titanium alloys, as well as B microalloying, which could decrease the grain size of titanium alloys during the casting process. As a key structural material, the study of the fatigue behavior of titanium alloys is crucial and always attractive for scientists. Hence, in this paper, the low cycle fatigue (LCF) behavior and fracture characteristics of a low-cost Ti-2Fe-0.1B alloy with a lamellar structure were investigated systematically, five different strain amplitudes (Δεt/2) in the range from 0.6% to 1.4% were selected to control the LCF process. It was found that the Ti-2Fe-0.1B alloy exhibits continuous cyclic softening behavior in the cycle as a whole at Δεt/2 ≤ 1.2%, while at Δεt/2 = 1.4%, it exhibits slight cyclic hardening at the initial stage of the cycle, then shows cyclic softening. Compared with pure titanium and other typical titanium alloys, the Ti-2Fe-0.1B alloy indicated maximum fatigue life under the same strain amplitude, it can be attributed to the fine grain size result from the effect of Fe element and trace B, which could hinder the dislocation movement and crack propagation. [ABSTRACT FROM AUTHOR]

This paper provides a review of models commonly used over the years in the study of microscopic models of material corrosion mechanisms, data mining methods and the corrosion-resistant performance control of structural steels. The virtual process of material corrosion is combined with experimental data to reflect the microscopic mechanism of material corrosion from a nano-scale to macro-scale, respectively. Data mining methods focus on predicting and modeling the corrosion rate and corrosion life of materials. Data-driven control of the corrosion resistance of structural steels is achieved through micro-alloying and organization structure control technology. Corrosion modeling has been used to assess the effects of alloying elements, grain size and organization purity on corrosion resistance, and to determine the contents of alloying elements. [ABSTRACT FROM AUTHOR]

High chromium cast iron (HCCI) has been widely used as wear-resistant material in the industry. Alloying is an effective way to improve the microstructure and mechanical properties of HCCI. This paper added multi-component V-Fe-Ti-Nb-C-Zr-B alloy (VFC) to HCCI, showing a significant synergistic solution-strengthening effect. The results show that the added V-Ti-Nb-B are dissolved in M7C3 carbide to form the (Cr, Fe, V, Ti, Nb)7(C, B)3 alloy carbide, and a small amount of V and all Zr are dissolved in austenite and martensite. Adding VFC into HCCI improved the hardenability of HCCI, decreased the residual austenite content from 6.0 wt% to 0.9 wt%, increased the martensite content from 70.7 wt% to 82.5 wt%, and changed the structure and content of M7C3 carbide. These changes increased the hardness of as-cast and heat-tread HCCI by 1.4% and 4.1%, increased the hardness of austenite and martensite by 7.9% and 7.0%, increased the impact toughness by 16.9%, and decreased the friction coefficient and wear loss by 2.3 % and 7.0 %, respectively. Thus, the hardness, toughness, wear resistance, and friction resistance of HCCI alloy are improved simultaneously. [ABSTRACT FROM AUTHOR]

Bulk amorphous or nanocrystalline Nd-Fe-based alloys show surprising hard magnetic properties. Its pronounced room temperature coercivity results from the high random anisotropy of ferromagnetic nanoclusters. In this paper, the magnetic characteristics of the mould-cast Nd70–xFe30Alx ( $x=0$ –10) alloys were studied in detail. The substitution of Nd by Al could improve the glass forming ability, reduce the coercivity and Curie temperature, and suppress the formation of Nd2Fe17 phase. The microstructure consisting of 5–20 nm-sized dHCP Nd phases embedded in the amorphous phase was evident. The room temperature coercivities decreased from 340 to 270 kA/m with increasing Al content. The domain structure was investigated by magnetic force microscopy. The temperature dependence of the coercivity could be well explained by the strong pinning model of domain walls of Gaunt. The double layer hexagonal-close-packed (dHCP) Nd phase works as the pinning center. The Hopkinson peak was also investigated using the mathematical formalism based on the Stoner-Wohlfarth model. The hard magnetic properties of the alloys disappeared after heat treatment at 873 K, since part of the amorphous phase and the ferromagnetic clusters transferred into Th2Zn17-type phases and some unknown phase. This paper provides further insights into the origin of the hard magnetism for the amorphous and nanocluster alloys. [ABSTRACT FROM AUTHOR]

Rare earth elements and transition elements are widely used in aluminum alloys, magnesium alloys and copper alloys due to their unique microalloying effects. With regard to in-depth research on the grain refinement characteristics of rare earth elements and transition elements, the combination of grain refinement and microalloying in the master alloys has a great impact on the theories and technical research of refinement, and the broadening of the application field of master alloys. This paper first summarizes the grain refinement mechanisms and analyzes the effects of rare earth elements and transition elements on the grain refinement of aluminum and aluminum alloys, and summarizes the elements suitable for the preparation of Al-M master alloys and their refinement mechanism. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the effects of vanadium on the strength and ductility of medium-manganese steels by analyzing the microstructural evolution and strain hardening rates and performing quantitative calculations. Two significantly different contents of vanadium, 0.05 and 0.5 wt.%, were independently added to model steel (0.12C-10Mn) and annealed at different intercritical temperatures. The results show that higher vanadium addition increases the yield strength but decreases the ductility. The maximum yield strength can increase from 849 MPa to 1063 MPa at low temperatures. The model calculations reveal that this is due to a precipitation strengthening increment of up to 148 MPa and a dislocation strengthening increment of 50 MPa caused by a higher quantity of V4C3 precipitates. However, the high density of vanadium carbides leads them to easily segregate at grain boundaries or phase interfaces, which prevents strain from uniformly distributing throughout the phases. This results in stress concentrations which cause a high strain hardening rate in the early stages of loading and a delayed transformation-induced plasticity (TRIP) effect. Additionally, the precipitates decrease the austenite proportion and its carbon concentrations, rendering the TRIP effect unsustainable. Accordingly, the ductility of high vanadium steels is relatively low. [ABSTRACT FROM AUTHOR]

The application of Nb microalloying to high-carbon pearlite bridge cable wire rod steel has always been controversial, especially in the actual production process, which will be affected by the cooling rate, holding temperature and final bonding temperature. In this paper, the experimental characterization, finite element simulation and phase diagram calculation of the test steel were carried out, then the microstructure and properties of different parts of Nb microalloying of bridge cable wire rods were compared and analyzed. The phase transition interval of pearlite during the water-cooling process of bridge cable wire rods is increased due to the refinement of austenite grains, and the significant increase in the end temperature of the phase transition makes the average interlamellar spacing of pearlite increase. The cooling rate of different parts of bridge cable wire rods simulated by Abaqus has little difference. At the same time, Nb microalloying effectively increases the proportion of low-angle grain boundaries, so that the overall average misorientation representing the surface defects is reduced. This helps to reduce the surface energy and increase the stability of the microstructure. Combined with the mechanical properties of microtensile rods, it is found that the grain refinement effect of Nb is greater than that of coarsening interlamellar spacing during hot rolling deformation in actual production, which makes the tensile strength at the 1/4 section increase significantly. The overall tensile strength and area shrinkage of the steel wire have also been effectively improved. [ABSTRACT FROM AUTHOR]

Nickel aluminides have desirable properties for use in high-temperature applications. Nickel aluminides have certain desirable qualities, but for almost a decade in the 1990s, those benefits were overshadowed by the challenges of processing and machining at room temperature. Manufacturing improvements, increased knowledge of aluminide microstructure and deformation processes, and developments in micro-alloying have all contributed to the development of nickel aluminides. Key developments in nickel aluminides, such as their microstructure, alloy addition and alloy development, are given and discussed at length. Methods of production from the past, such as ingot metallurgy and investment casting and melting are addressed, and developments in powder metallurgy-based production methods are introduced. Finally, the difficulties of producing nickel aluminides and possible solutions are examined. This paper gives an overview of the fundamentals, preparation, processing, applications and current trends in nickel aluminides. [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 paper gives the results of investigation of the influence of application of two isolated filler wires or embedded elements of different chemical composition on the features of formation of D16 aluminium alloy welds in consumable electrode welding. Wires of Zv1201, ZvAK5, ZvAK12 grades of 1.6 mm diameter and embedded elements cut out of V92, V96 and 7056 alloy blanks with different content of zinc were evaluated. It is shown that ZvAK5 wire ensures reduction of the length of solidification cracks and number of pores in welded joints, and welded joint strength becomes higher at addition of zinc into the weld. [ABSTRACT FROM AUTHOR]

The effect of boron addition into Fe–28Al–5Si–X (X = -, 2Mo, or 2Ti) on the structure and high-temperature yield stress was investigated. Generally, the alloying of binary Fe3Al-type iron aluminides by silicon significantly improves high-temperature mechanical properties by solid-solution strengthening. On the other hand, the workability and ductile properties at room or slightly elevated temperatures get worse with the increasing silicon content. Boron alloying together with titanium or molybdenum alloying is one of the ways to improve the workability of this type of alloy and, at the same time, ensure the formation of a sufficient amount of secondary phase particles required for effective strengthening. In this paper, the influence of 1 at. % of boron on high-temperature yield stress is evaluated in response to structural changes and compared with results obtained previously on the same type of alloy (Fe–28Al–5Si–2X, X= -, Mo, or Ti) but without boron alloying. It can be concluded that the network structure of borides of refractory metals formed due to boron alloying works more effectively for alloy hardening at higher temperatures than a mixture of silicides and carbides present in the boron-free alloy of the same composition. [ABSTRACT FROM AUTHOR]

Summary: Herein, we report a new strategy of Ba micro‐alloying to enhance the anode properties of the Mg‐air primary battery anode materials. The influence of Ba micro‐alloying on electrochemical behavior, corrosion resistance, and discharge properties of Mg‐6Al anodes in Mg‐air batteries was specifically investigated. Ba micro‐alloying markedly improved the corrosion resistance of Mg‐6Al alloys, which was due to the grain refinement and the inhibition of the cathodic hydrogen evolution reaction. However, when Ba content reached 0.7 wt.%, the coarse Al13Ba7 phase accelerated the galvanic corrosion and increased the corrosion rate. Moreover, the Mg‐6Al‐0.4Ba anode had the optimal discharge capacity and anode efficiency at 20 mA cm−2 with 893.66 mAh g−1 and 39.36%, respectively, which was 22.1% and 22.4% higher than that of the Mg‐6Al anode. The enrichment of discharge properties was attributed to the refinement of grains and the improvement of the self‐corrosion resistance. In addition, Ba micro‐alloying improved the absorption capacity of the anode, which was conducive to the self‐exfoliation of the discharge products. The Novelty Statement: This paper prepared the Mg‐6Al‐xBa anodes by Ba micro‐alloying to enhance the discharge properties. The generation of Al13Ba7 phase and the refinement of grains caused by Ba addition reduced the corrosion rate and increased the discharge capacity and anodic efficiency of Mg‐6Al alloy. Thus, Ba micro‐alloying can improve the corrosion resistance and discharge performance of Mg‐6Al alloy. [ABSTRACT FROM AUTHOR]

AZ31 magnesium alloy sheets can be applied as 3C electronic product shells. However, AZ31 sheets exhibit obvious anisotropy, which limits their industrial application range. The composition modification of AZ31 is a good choice to improve the anisotropy of the sheets, but the effect of the multi-element micro-alloying on the microstructure and anisotropy of AZ31 alloy sheets is still less investigated. For this aim, the plasticity and anisotropy of AZ31 sheets after adding Ca and rare earth elements such as Y and Gd were investigated in this paper. It is found that, different from the alloying role of single Ca or Ca and Y, the composite addition of 0.2Ca and 0.2Gd can obviously enhance the anisotropy of AZ31 alloy sheets. As a result, the elongation of AZ31 in the rolling direction (RD) direction, 45° direction, and transverse direction (TD) direction is increased from 12.5% to 22%, from 5% to 18.5%, and from 1.5% to 8.5%, respectively. This can be explained as follows: the Al8Mn4Gd phase formed by the addition of Gd consumes a lot of Mn, thus avoiding the formation of brittle phases Al8Mn5 and leading to the improved mechanical properties of the alloy sheets. This study will offer a good solution for enhancing the formability of AZ31 sheets under the condition of not significantly increasing the production costs. [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 study, a multi-element microalloyed GCr15Si1MoNbV bainitic bearing steel was designed by adding trace amounts of Nb and V. The bainite/martensite/retained austenite/undissolved carbide multiphase bearing steel with a short heat-treated cycle and remarkable comprehensive mechanical properties was prepared via low-temperature austempering, which was compared with a traditional quenched and tempered martensitic microstructure. The results showed that the comprehensive mechanical properties of the low-temperature bainitic microstructure of the Nb/V microalloyed bearing steel were better than those of a traditional tempered martensitic microstructure. In addition, as the isothermal temperature increased, the impact toughness of experimental steel was significantly improved, and the hardness decreased slightly. The tensile strength was improved with the increase in isothermal time. As the isothermal temperature increased, the bainite content of the experimental steel rose, and the stability of the retained austenite enhanced due to more carbon atoms being partitioned into it. The research work in this paper made a preliminary exploration for the application of Nb/V microalloyed bainitic bearing steel in the bearing field and provided some basic data for reference. [ABSTRACT FROM AUTHOR]

The peculiarities of the glow discharge mass-spectrometry (GDMS) analysis of the main components and elements of microalloying of high-entropy AlCrFeCoNiCu alloy are considered in the paper. Molecular interferences of ArxAy + i, ArxG+ i, AxBy + i types (where A, B are the components of the sample, G are single and 2-3 atomic gases; x, y = 1, 2, i - charge of ion, i = 1, 2), which are formed during cathode sputtering of this alloy in glow discharge plasma were calculated and experimentally tested. It is shown for spectrometers at resolution R0.5 = 7000, the greatest influence of molecular ions of Me2 + and ArMe+ types exist in the range of isotope masses from 85Rb to about 107Ag. A careful selection of isotopes is required in this mass range to meet detection limit conditions. In other areas of the mass spectrum, the sensitivity of the analysis is limited by the background current and the sensitivity of the detectors and is at the usual ppb-level for this method. [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]

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This paper investigates dynamical behavior of magnetic Barkhausen noise (BN). The measurements were performed for a soft mild steel at controllable magnetizing conditions: 1) the fixed sinusoidal/triangular waveforms of the magnetic induction or 2) the surface magnetic field. Two vertically mounted Hall sensors were used for direct determination of the sample magnetic field. The BN was detected locally by a surface-mounted coil. A typical two-peak shape of the BN envelope was found to reduce to a usual single-peak profile at the constant field rate. These two peaks were shown to correspond to the regions of the magnetic domain reconfiguration preceding and following the rapid magnetization reversal at the coercive field. In ac magnetizing frequency range of 0.2–30 Hz, the BN parameters followed a nearly square root dependence on the frequency. A low-frequency component of the BN signal, approximately up to 25 kHz, was revealed to contain an important part of the micromagnetic information. [ABSTRACT FROM AUTHOR]

The paper deals with the influence of manganese in AlSi7Mg0.3 alloy with higher iron content. Main aim is to eliminate harmful effect of intermetallic - iron based phases. Manganese in an alloy having an iron content of about 0.7 wt. % was graded at levels from 0.3 to 1.4 wt. %. In the paper, the effect of manganese is evaluated with respect to the resulting mechanical properties, also after the heat treatment (T6). Morphology of the excluded intermetallic phases and the character of the crystallisation of the alloy was also evaluated. From the obtained results it can be concluded that the increasing level of manganese in the alloy leads to an increase in the temperature of the β-Al5FeSi phase formation and therefore its elimination. Reducing the amount of β-Al5FeSi phase in the structure results in an improvement of the mechanical properties (observed at levels of 0.3 to 0.8 wt. % Mn). The highest addition of Mn (1.4 wt.%) leads to a decrease in the temperature corresponding to the formation of eutectic silicon, which has a positive influence on the structure, but at the same time the negative sludge particles were also present. [ABSTRACT FROM AUTHOR]

The influence of the microalloying elements of 34CrNiMo6 steel on the microstructure and mechanical properties is investigated in this paper, especially Al and N. Then, the testing of the tensile strength, yield strength, elongation after breakage, and impact absorbing energy under the different conditions is carried out to compare the mechanical properties of materials. Based on the experimental results, the evolutions of mechanical properties with the content of aluminum are obtained. The average grain size test and scanning electron microscope results illustrate that the strengthening mechanism is the pinning effect of aluminum nitride. [ABSTRACT FROM AUTHOR]

This paper deals with the role of minor addition of Cr on the atomic rearrangement and crystallization evolution in a Zr-based bulk metallic glass. For this purpose, Cr elements with 1–4% atomic percentage were added into the alloying composition. The X-ray diffraction results indicated that the trace element led to the increase in disordered structures in the glassy alloy and the decline in population of short and medium scale orders. This event was due to the intensification of structural heterogeneity which was manifested in the change of enthalpy relaxation. The differential scanning calorimetry analysis also showed that all ZrCoAlCr BMG samples included two distinct crystallization peaks during the heating process. However, the increase in Cr content led to the intensification of low temperature peak. This result was consistent with viscosity analysis, in which the viscosity decrement was intensified at the range of low temperature crystallization peak with the rise in Cr content. Moreover, it was found that although the plasticity improved in samples with Cr-content, the strength showed a slight decrease. [ABSTRACT FROM AUTHOR]

The influence of calcium microalloying on the texture of aluminum Al–Mg–Li and Al–Mg–Si–Cu alloys is studied. The paper considers the mechanical properties at static and dynamic loads, the fatigue characteristics, the crack resistance, and the high-temperature strength of V1341 alloy sheets with a regulated recrystallized structure in state T1. The properties of the sheets are also determined after long-term heating at 100–150°C for 10–1000 h. The results of service and corrosion tests of the sheets are presented. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is a cheap and effective element that inhibits grain growth and improves soft magnetic properties in Fe-based nanocrystalline alloys. However, most alloys usually require high P content, leading to problems such as volatilization and oxidation during production process. In this paper, we study and report new findings regarding the effect of P microalloying on the magnetic properties, microstructure and magnetic domain structure of Fe77.8Si10B9−xCu0.6Nb2.6Px (x = 0 and 1) nanocrystalline alloys. The substitution of B by 1 at% P has little influence on the crystallization behavior, saturation magnetic flux density (Bs) and permeability (μ) of the alloy, while effectively reduces the coercivity (Hc) in a wide annealing temperature range. The reduced Hc can be attributed to the low magnetocrystalline anisotropy and wide magnetic domains caused by uniform and fine α-Fe(Si) grains. The mechanism of structural evolution induced by 1 at% P is also been discussed. The P microalloyed nanocrystalline alloy with high Bs of 1.43 T, high μ up to 27,000 at 1 kHz, and low Hc of 1.4 A/m is suitable for magnetic shielding piece of wireless charging. [ABSTRACT FROM AUTHOR]

The paper deals with the possibility of constructing mathematical models of the dependence of mechanical properties of silicon-manganese steels designed for ESW, which have high brittle fracture resistance in the HAZ, as well as of the overheated zone, on chemical composition. Data on mechanical properties of these steels were obtained as a result of studying the influence of additional alloying (microalloying) of silicon-manganese steel by manganese, chromium, vanadium, boron, cerium and zirconium, on overheating resistance at electroslag welding. The method of multiple linear regression was used for construction of mathematical models. Mathematical models were constructed for the following set of base metal mechanical properties: impact toughness for temperatures of (+20, -40, -60, -70 °C), yield limit, ultimate strength, relative elongation and reduction in area. For overheated zone at electroslag welding mathematical models were constructed for impact toughness (KCU and KCV) for temperatures of +20, -60, -70 °C. Initial validation of the constructed models was performed. [ABSTRACT FROM AUTHOR]

The paper deals with the possibility of constructing mathematical models of the dependence of mechanical properties of silicon- manganese steels designed for ESW, which have high brittle fracture resistance in the HAZ, as well as of the overheated zone, on chemical composition. Data on mechanical properties of these steels were obtained as a result of studying the influence of additional alloying (microalloying) of silicon-manganese steel by manganese, chromium, vanadium, boron, cerium and zirconium on overheating resistance at electroslag welding. The method of multiple linear regression was used for construction of mathematical models. Mathematical models were constructed for the following set of base metal mechanical properties: impact toughness for temperatures of (+20, –40, –60, –70 °С), yield limit, ultimate strength, relative elongation and reduction in area. For overheated zone at electroslag welding mathematical models were constructed for impact toughness (KCU and KCV) for temperatures of +20, –60, –70 °С. Initial validation of the constructed models was performed. 9 Ref., 12 Tabl., 2 Fig. [ABSTRACT FROM AUTHOR]

Methods of economical alloying of high pipe steels were considered in the paper. Due to the large environmental, energy, and economic issues in the destruction of the pipeline, the quality of steel pipes is very important. The method described in this article is considered to be relevant not only for pipe steels but also for high-strength steels used in shipbuilding, bridge construction, etc. Review mechanisms of strengthening microalloyed steels were carried out in this work. Schema evolution of the microstructure of microalloyed steels was discussed. The influence of alloying elements in steel by means of optimal process parameters of thermomechanical rolling was analyzed. There are two methods of mathematical modeling used in the study: artificial neural networks (ANNs) which are based on the multilayered perceptron to select the optimal chemical composition and finite element analysis to optimize the process parameters. An experimental dataset was used to train multilayer perceptron (MLP) networks to allow for prediction of the yield strength, tensile strength, and elongation of steel. Due to large availability, low cost, and high accuracy of the results, these methods are considered to be the most promising ones. The mathematical model for calculating mechanical properties of a rolling pipe has been developed. Two ways to reduce the cost of a hot-rolled plate made of microalloyed steels were developed. There has been developed the complex of replacement technological impact which can make it possible to replace or reduce the amount of expensive chemical elements (vanadium, nickel, copper, manganese, chromium, and niobium) without loss of quality. [ABSTRACT FROM AUTHOR]

The production of heavy steel forgings of micro-alloyed steels gives the possibility to obtain advantages associated with the benefit of the application of micro-alloying elements and thermo-mechanical treatments for improving the mechanical properties of forgings up to level by sheets, strips and tubes. In order to do that, the effect of V addition has been exploited by means of metallurgical modelling followed by a laboratory ingot manufacturing. Heat treatment has been designed aimed to achieve the desired target tensile properties. Results show that ASTM A694 F70 grade requirements can be fulfilled by 0.15% V addition and a proper heat treatment in a ferrite-pearlite microstructure, representative of a forged component. In this paper the influence of quenching and tempering (Q&T) temperatures on the mechanical properties and microstructure of F70 steel according to ASTM A694 is reported. [ABSTRACT FROM AUTHOR]

This paper focuses on developing an advanced test method and its use to study hot tearing defects in aluminium alloy castings. The paper consists of two parts. The first part introduces the reader to hot tearing in general, and provides theoretical analysis of the hot tearing phenomenon. The second part describes a newly developed method for assessing hot tearing susceptibility, and also gives the results on hot tearing for various aluminium alloys. During the test, the effect of alloy chemical composition on hot tearing susceptibility was analyzed. Three different Al-based alloys with varying Si, Cu and Ti contents were examined. Conclusions deal with the effect of individual elements on hot tearing susceptibility, and confirm that the main objective was achieved and the proposed method proves to be repeatable and reliable. [ABSTRACT FROM AUTHOR]

During Supersolidus Liquid Phase Sintering the viscosity of beams affects the deflection level, thus in sintering practice also the tendency to distortion. Although the deflection value increases with decreasing viscosity, a concentration gradient from surface to centre of samples may neutralise the effect of viscosity. In this paper, the deflection behaviour of Cu-28Zn beams, manufactured from prealloyed powder, at various temperatures and times ranging from 910 to 950°C and 0–90 min, respectively, was studied. The midpoint deflection was measured by the in situ bending images. To better understand the deflection behaviour, experimental results were mathematically modelled using general deflection equations. To obtain further information, microstructural studies were performed using optical and scanning electron microscopy. It is concluded that zinc evaporation influences the chemical composition and generates a thin solid layer around the sample resulting in a parabolic deflection behaviour with temperature and non-linear with time. [ABSTRACT FROM AUTHOR]

In this paper, the microstructure of the alloy has been modulated by the multivariate microalloying technique, aiming to reveal the intrinsic relationship and mechanism of intergranular corrosion and stress corrosion cracking. The addition of V to 2519 alloy changed the distribution characteristics of grain boundary precipitates and the dislocation density was reduced by 22.5 %, and the intergranular and stress corrosion cracking properties of the alloy were improved by 14.1 % and 40.7 %, respectively. Interestingly, grain deflection with /48°-58° axial angle relationship was found during stress corrosion crack propagation and the alloy had the best stress corrosion resistance. [Display omitted] • Revealing the strengthening mechanism of multivariate microalloying on the intergranular corrosion performance of 2519 alloy. • To elucidate the inherent connection between different alloy microstructures and SCC sensitivity. • The axial angle relationship for grain deflection during SCC crack propagation is presented. [ABSTRACT FROM AUTHOR]

With the rapid development of the automotive industry, the requirements for bodywork materials are not only focused on high strength but also on improved forming properties. To develop a new generation of automotive steels with higher strength–plasticity matching, a high elongation 1200 MPa grade V-Nb microalloyed cold-rolled reinforced formable dual-phase steel was developed in this experiment through rational compositional design and precise process machining. The properties of the test steel are improved by varying the over-aging temperature as well as the annealing temperature to achieve a good strength–plasticity balance. The results show that as the aging temperature increases, the tensile strength and yield strength of the test steel decrease, while the elongation continues to increase. At an aging temperature of 310 °C, the steel exhibits not only high strength but also better ductility. As the annealing temperature increases, the tensile strength and yield strength of the test steel initially increase and then decrease, while the elongation continues to increase. When the heat treatment process involves an annealing temperature of 860 °C and an over-aging temperature of 310 °C, the test steel achieves the best strength–plasticity balance. [ABSTRACT FROM AUTHOR]

By substituting Al with Si element, the Fe36Ni36Cr10Mo1Al17−XSiX (X = 0, 1, 2 and 4) alloys were prepared and their mechanical properties were tested at high temperature ranging from 600 to 800 °C. The yield strength and ultimate tensile strength of the 4 alloys showed a trend of increasing first and then decreasing when tested at 700 °C. All the alloys with Si added showed enhanced strength and elongation compared with the alloy without Si addition. Fe36Ni36Cr10Mo1Al15Si2 exhibited the highest yield strength of 516 MPa, ultimate strength of 570 MPa, and elongation of 13.1% at 700 °C. The 2% Si addition increases the ultimate strength by 102 MPa compared with Si0 alloy (468 MPa), which is attributed to the strengthened boundaries with addition of Si element. Moreover, the yield strength and ultimate strength of the Fe36Ni36Cr10Mo1Al15Si2 alloy represented a decreasing trend while elongation showed an increasing trend as temperature increased from 600 to 800 °C. The rapid reduction of the strength and increase of the elongation was originated from the rapid softening of the B2 phase at 800 °C compared with that of FCC phase. [ABSTRACT FROM AUTHOR]

Due to the prominent advantages of low density, high elastic modulus, high specific strength and specific stiffness, cast Al-Li alloys are suitable metallic materials for manufacturing complex large-sized components and are ideal structural materials for aerospace, defense and military industries. On the basis of the microstructural characteristics of cast Al-Li alloys, exploring the role of alloying and micro-alloying can stabilize their dominant position and further expand their application scope. In this review, the development progress of cast Al-Li alloys was summarized comprehensively. According to the latest research highlights, the influence of alloying and heat treatment on the microstructure and mechanical properties was systematically analyzed. The potential methods to improve the alloy performance were concluded. In response to the practical engineering requirements of cast Al-Li alloys, the scientific challenges and future research directions were discussed and prospected. [ABSTRACT FROM AUTHOR]

This study explores the effects of Zn addition through micro-alloying on the microstructure and discharge performance of Mg-Al-Mn-Ca alloy anodes for magnesium-air batteries. The results show that the second-phase particles (d > 1 μm) in a Mg-Al-Mn-Ca alloy promote dynamic recrystallization (DRX) via particle-stimulated nucleation (PSN), resulting in a uniform equiaxed grain structure and fiber texture. In contrast, Zn and Ca co-segregation in a Mg-Al-Mn-Ca-Zn alloy facilitates continuous dynamic recrystallization (CDRX) and, combined with the PSN mechanism, forms a unique structure where three types of grains with different grain boundary densities coexist. The addition of Zn and Ca effectively reduces the c/a axis ratio, promoting texture homogenization. The Mg-Al-Mn-Ca alloy exhibits rough discharge surfaces due to simultaneous discharge at numerous grain boundaries and severe hydrogen evolution corrosion from micro-galvanic effects, inducing the chunk effect (CE). Conversely, the structure where three types of grains with different grain boundary densities coexist in the Mg-Al-Mn-Ca-Zn alloy promotes discharge product detachment through stress cracking, achieving uniform discharge and significantly enhancing discharge performance. The uniform texture reduces hydrogen evolution corrosion, improving anode utilization. This study demonstrates that controlling the microstructure, particularly grain boundary density and grain texture, enables the development of high-performance Mg-Al-Mn-Ca-Zn alloy anodes, especially at higher current densities, offering a new strategy for designing efficient magnesium alloy anode materials. [ABSTRACT FROM AUTHOR]