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TiAl-based composites have broad application prospects in the aerospace and automotive fields due to their excellent high-temperature properties. In this study, the B/N synergistic effect on microstructural evolution, mechanical properties and fracture behavior was investigated by addition of nano-BN particles to Ti-46.8Al-8.0Nb alloy (at%). It was found that the B reacted with the Ti and Nb in the high-Nb TiAl matrix to form needle-shaped borides of TiB, TiB2 and NbB, which in turn reduced the lamellar colony size by inhibiting the movement of grain boundaries during the sintering process, while the N atoms diffused into the octahedral interspaces of the γ and α2 lattice. The lamellar colony size can be greatly reduced from 351 ± 144 μm to 44 ± 10 μm. The as-sintered microstructure can be gradually transferred from fully lamellar (FL) to dual phase (DP) with increment of nano-BN content. Composite containing 0.75 at% nano-BN exhibit the highest ultimate tensile strength at room temperature, reaching 660 ± 12 MPa. At high temperatures, the composite containing 1.50 at% nano-BN exhibits the highest ultimate tensile strength, reaching 517 ± 9 MPa. The mechanism of improved mechanical properties is attributed to grain refinement strengthening, thermal mismatch strengthening, Orowan strengthening, solid-solution strengthening.

An in-situ dual morphology of Ti2AlC/TiB2 nanoparticles was refined and enhanced to fabricate Ti-47.7Al-7.1Nb-2.3V-1.1Cr composites via induction hot-pressing sintering with nano-B4C addition. The generation process of nanoparticles, lamellar refinement mechanism, and effect of nanoparticles on the microstructure evolution/mechanical properties were meticulously analysed. With 0.2 at% nano-B4C addition, Ti2AlC/TiB2 nanoparticles were uniformly distributed in the matrix following sintering. In addition, upon sintering at 1425 °C for 10 min under a pressure of 50 MPa, the lamellar colony size decreased from 280 ± 145 μm to 55 ± 16 μm, and the ultimate tensile strength (UTS) increased by 116 MPa, 142 MPa, and 176 MPa, when tested at room temperature, 800 °C, and 900 °C, respectively. The enhanced mechanical properties were attributed to the synergistic effects of grain refinement strengthening, solid solution strengthening, the Orowan mechanism, and twinning strengthening.

TiAl is used as the preferred material for aero-engine low-pressure turbine blades, which is also faced with similar problems of “Titanium fire” under long-term high temperature service conditions. In this paper, the micro-combustion behavior of TiAl is discussed. It is found that the flame-retardant of the TiAl alloy has better performance compared to that of TC11, TA11. In this regard, the higher content of Al and Nb is identified as the primary reason for the superior flame-retardant performance for TiAl alloy. Moreover, the segregation serves as a transport channel for atoms and entraps oxygen atoms during the process of extended combustion. The three-stage combustion model before deflagration is presented. Furthermore, the flame-retardant mechanism before and after deflagration is explained, highlighting the main reason behind the formation of the final morphology of the alloy after combustion.

Improving both the magnetic properties and strength of non-oriented electrical steel used in driving motors of new energy vehicles is a great challenge. In this study, a 4.5 wt% Si non-oriented electrical steel that had a strong {114} texture and exhibited excellent magnetic and high strength, was produced via hot rolling, cold rolling and annealing. The texture evolution of hot-rolled plate with strong Goss and medium strength λ-fiber ({100}) was investigated in detail during rolling and annealing. The VPSC model was used to simulate the texture evolution during the rolling process, of which the neff model could satisfactorily explain the classical rotation route of Goss and Cube. At the initial stage of recrystallization, the orientation of the recrystallized grains, characterized by electron backscatter diffraction (EBSD), was closely related to the orientation of the hot-rolled plate and rotation path during the rolling process. This clear evidence indicated that the initial recrystallized grains were oriented nucleation. During the recrystallization process, the characterization of specific orientations by quasi-in-situ EBSD revealed that the unusual {114} was formed by an oriented growth mechanism. Texture evolution during the recrystallization indicated oriented nucleation as an inherent property responsible for the initial recrystallization texture, while oriented growth was influenced by deformed grain size and grain boundary characteristics.

Here, an electron beam selective melting (EBM) technique was employed to shape Ti–48Al–2Cr–2Nb alloy to combat its intrinsic brittleness and insufficient hot workability. Through process optimization, high-density samples (4.2327 g/cm3) were produced. First, the mechanism of interaction between phase transformation and microstructural evolution of EBM-formed Ti–48Al–2Cr–2Nb alloy was investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and electron backscattering diffraction (EBSD). And then, the mechanism of interaction between tensile properties and microstructural evolution of EBM-formed Ti–48Al–2Cr–2Nb alloy was discussed. Based on the results, the microstructure consists of coarse equiaxed grains and fine lamellar grains, which gradually coarsen from upper to bottom. As the thickness of the layer increases from upper to bottom, the content of the B2 phase increases continuously, with a predominant component of TiAl and a small amount of Ti3Al and B2 phases. The majority of the γ-TiAl phase does not exhibit significant texture, while the α2-Ti3Al phase shows a texture of (0001) with 19.32 times the random intensity, and its c-axis is parallel to the deposition direction. Benefiting from its unique structure features, the maximum room temperature tensile strength of as-deposited Ti–48Al–2Nb–2Cr alloy reaches 854.6 MPa with an elongation of over 2%. And the maximum high-temperature tensile strength of EBM-formed Ti–48Al–2Nb–2Cr alloy reaches 707 MPa at 650 °C with an elongation over 3.5%. According to these results, the mechanical properties of our EBM Ti–48Al–2Cr–2Nb alloy are superior to those previously reported.

Additively manufactured Ni-based superalloys exhibit strong anisotropy due to microstructural differences resulting from their unique fabrication method. This study systematically investagiated the microstructure and mechanical properties of Ni-based GH4099 alloy fabricated by Selective Laser Melting (SLM) with subsequent heat treatment (HT). The causes of anisotropy in the deformation mechanism of alloys at room temperature and high temperatures are discussed. The results indicate that epitaxial grain growth occurs along the building direction, and after SLM, entangled dislocations gather at the cell boundaries. After HT, high-density dislocations are eliminated, while most grains remain in the as-deposited form. At room temperature, the deformation mechanism of the alloy remains consistent. Cracks generate and propagate inside grains, while grain boundaries provide a more substantial barrier for dislocations. Therefore, the difference in mechanical anisotropy depends on the difference in grain morphology in the build direction and perpendicular to the build direction. At high temperatures, fracture failure occurs at grain boundaries. The growth of carbides at high temperatures leads to the weakening of grain boundaries. The alloy exhibits different deformation mechanisms when loaded along the short and long axes of the grain. Only dislocations are activated when loaded along the short axis of the grain. Stacking faults and deformation twins provide higher plastic-deformation ability when loaded along the long axis of the grains. Moreover, dislocations also activate, however the dislocation density is lower compared to loaded along the short axis.

This study systematically investigated the high cycle fatigue behaviors and deformation mechanisms in Ti47Al2Cr2Nb alloy at room temperature and 700 °C through scanning electron microscope and transmission electron microscope. The results showed that high temperature deteriorated the fatigue performances, especially under the higher stress levels. Large scatter in fatigue lifetimes under the lower stress levels was observed at high temperature. After 107 cycles, the high cycle fatigue limit at 700 °C was about 20 MPa lower than that at room temperature. Fracture morphologies showed that brittle fracture presented at both temperatures and fatigue cracks initiated from the surfaces. Fracture modes at room temperature included trans-lamellar and trans-γ grain fractures, while those at 700 °C included trans-lamellar, interlamellar and inter-γ gain fractures. Fatigue deformation at both temperatures mainly occurred in the γ phase, dislocation multiplication and slip bands were found in the deformation microstructures. Dislocation slip was the main deformation mechanism at both temperatures. A few mechanical twins were observed in the deformation microstructures of room temperature. Slip bands and mechanical twins transferred through γ/γ true-twin interfaces with a deflection while they transferred through γ/γ rotational boundaries straightly. Mechanical twins had a blocking effect on slip bands, resulting in the dislocation arrays in slip bands piling up at the intersections.

Abstract In this work, ultra-low dilution rate Inconel 625 coatings with a thickness of ~534.4 μm were prepared by high-speed laser cladding technique on the Q245R steel. The XRD and TEM results show that the Inconel 625 coatings are mainly composed of the Nb and Mo-enriched laves phase with hexagonal close-packed (HCP) structure and the γ-Ni phase with face-centered-cubic (FCC) structure. The cellular crystal, column crystal, and equiaxed dendritic crystal were observed in the bottom, middle, and top of the Inconel 625 coatings from SEM results, respectively. The wear resistance and corrosion resistance of Q245R steel are significantly improved by high-speed laser cladding Inconel 625 coatings. In addition, the low dilution rate is beneficial for improving the wear and corrosion resistance of high-speed laser cladding Inconel 625 coatings. These findings may provide a method to design the wear and corrosion resistance of coatings on steel's surface.

TiAl alloys have excellent high-temperature performance and are potentially used in the aerospace industry. By controlling the lamellar orientation through directional solidification (DS) technology, the plasticity and strength of TiAl alloy at room temperature and high temperatures can be effectively improved. However, various difficulties lie in ensuring the lamellar orientation is parallel to the growth direction. This paper reviews two fundamental thoughts for lamellar orientation control: using seed crystals and controlling the solidification path. Multiple specific methods and their progress are introduced, including α seed crystal method, the self-seeding method, the double DS self-seeding method, the quasi-seeding method, the pure metal seeding method, and controlling solidification parameters. The advantages and disadvantages of different methods are analyzed. This paper also introduces novel ways of controlling the lamellar orientation and discusses future development.

High niobium content TiAl alloys and Al2O3 ceramics were successfully joined using novel Nb particle-reinforced Ag–Cu composite filler. The changes in microstructure brazing at different temperatures were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The corresponding mechanical properties were studied by shear tests. The results showed that the brazed joints prepared at 900 °C can be divided into three zones. The typical microstructure of the brazed joints is high niobium content TiAl/AlCuTi + AlCu2Ti/Ag(s,s)+Cu(s,s)+Nb/Ti3(Cu,Al)3O/Al2O3. The brazing temperature was shown to have a significant influence on the microstructure and reaction layer thickness. After brazing at 810 °C, macrodefects could be observed in the brazing seam. At higher brazing temperatures, brazed joints without any defects were obtained. The addition of Nb particles and the suitable thickness of the Ti3(Cu,Al)3O reaction layer are the main reasons for the high shear strength. When brazing at temperatures higher than 900 °C, the volume fraction of the brittle AlCu(Ti, Nb) phase was increased and a thick Ti3(Cu,Al)3O reaction layer was formed, which deteriorated the shear strength of the joint. The maximal shear strength joint reached 228 MPa at 870 °C for 10 min, which is a substantial increase compared with conventional brazing processes.

Abstract Porous intermetallic membrane with extensive interconnected pores are potential candidates as functional materials for high-temperature particulate matter (PM) capturing. However, fabrication of intermetallic membrane with a combined performance of high filtration efficiency and high-temperature oxidation resistance remains a challenge. To tackle this issue, a hierarchical micro-/nano-dual-scale sized pores was constructed on the inner cell walls of a porous support through mutual diffusion and chemical reaction. Benefited from its hierarchical micro/nano-dual-scaled pore structural features, the high Nb containing TiAl-based porous composite microfiltration membrane demonstrates ultrahigh PM>2.5 removal efficiency (99.58%) and favorable oxidation/sulfidation performance at high temperature. These features, combined with our experimental design strategy, provide insight into designing high-temperature PM filtration membrane materials with enhanced performance and durability.

The effect of the crystallographic direction and temperature on the mechanical properties of an FeNiCrCoMn high-entropy alloy (HEA) is explored by molecular dynamics simulations. The calculated static properties are in agreement with the respective experimental/early theoretical results. The calculated compressive yield stress along the direction of a single crystal/polycrystal is the same in order of magnitude as the experimental results. The yield stress and Young’s modulus of the single crystal show strong anisotropy. Unlike the single crystal, the polycrystal behaves as an isotropic and has strong ductility. It is found that the dislocations produced in the plastic deformation process of the HEA are mainly 1/6 Shockley dislocations. The dislocations produced under normal stress loads are far more than that in the shearing process. FCC transformation into HCP does not occur almost until yield stress appears. The yield stress, yield strain, and Young’s modulus reduce gradually with increasing temperature. The modulus of the single/double crystal under compressive and tensile loads presents an obvious asymmetry, while there is only a small difference in the polycrystal. The strain point is found to be the same for stress yielding, FCC-HCP phase transition, and dislocation density, varying from slow to fast with strain at the considered temperature.

The effect of both Nb content and heat input on the softening phenomenon of the heat-affected zone (HAZ) of low-alloy high-strength steel was studied through welding thermal simulation experiments. The microstructure evolution, density variation of geometrically necessary dislocation, microhardness distribution and the second phase precipitation behavior in HAZ was characterized and analyzed by combining the optical microscope, scanning electron microscope, high-resolution transmission electron microscope with microhardness tests. The results showed that the softening appeared in the fine-grain HAZ (FGHAZ) of the low-alloy high-strength steel with the polygonal ferrite and bainite microstructure. With an increase in Nb content, the FGHAZ softening was inhibited even with high heat input; however, the hardness shows little variation. On the one hand, the increase in the Nb content increased the volume fraction of high-strength bainite in the FGHAZ. On the other hand, the remarkable strengthening was produced by the equally distributed precipitation nanoparticles. As a result, the two factors were the main reason for the solution of the FGHAZ softening problem in the low-alloyed high-strength steel with the mixed microstructure of ferrite and bainite.

TiAl alloys have the potential to become a new generation of high-temperature materials due to their lightweight and high-strength properties, while the brittleness at room temperature and microstructure stability at elevated temperature are the key problems. The preparation of composite materials is an effective way to solve these problems, because the mechanical properties of TiAl matrix composites can be improved by the close combination of the reinforced phase and matrix. The preparation methods, microstructure, and mechanical properties of TiAl matrix composites reinforced by carbides are reviewed from the literature in this paper. A comprehensive summary of the effect of C on TiAl alloys can reveal the relationship between the microstructure and mechanical properties and provide guidance for subsequent experimental works. Two forms of C in TiAl matrix composites are reviewed: solid solutions in matrix and carbide precipitations. For TiAl alloys, the minimum carbon content for the carbide precipitation is about 0.5 at.% for low-Nb-containing TiAl alloys and about 0.8 at.% for high-Nb-TiAl alloys. An appropriate amount of C can improve the tensile properties and flexural strength of TiAl alloys. The hardness of the composites is higher than that of pure TiAl due to solution strengthening when the carbon content is low. The minimum creep rate of TiAl alloys can be reduced by one order of magnitude by adding C at the amount near the solubility limit.

In-depth analyses of the anti-oxidation behavior and structure of γ-TiAl alloys are of great significant for their maintenance and repair in engineering applications. In this work, fluorine-treated Ti-45Al-8.5Nb alloys and fluorine-treated oxidized specimens with artificial defects were prepared by isothermal oxidation treatment at 1000 °C. Several characterization methods, including SEM, EDS, XRD and TEM, were used to evaluate the surface microstructure of the fluorine-treated Ti-45Al-8.5Nb alloys and fluorine-treated oxidized specimens with artificial defects. The results indicate that the fluorine promoted the formation of an outer protective film of Al2O3, which significantly improved the oxidation resistance. The microcracks of oxidized specimens with the artificial defects provided a rapid diffusion passage for Ti and O elements during the 1000 °C/2 h isothermal oxidation treatment process, resulting in the quick growth of TiO2 toward the outside. The fine Al2O3 constituted a continuous film after the 1000 °C/100 h isothermal oxidation treatment. In particular, Al2O3 particles grew toward the substrate, which was ascribed to the good oxidation resistance and adhesion. These results may provide an approach for the repair of protective oxide film on the surface of blades and turbine disks based on γ-TiAl alloys.

TiAl-based porous microfiltration membranes are expected to be the next-generation filtration materials for potential applications in high-temperature flue gas separation in corrosive environments. Unfortunately, the insufficient high-temperature oxidation resistance severely limits their industrial applications. To tackle this issue, a Ti-40Al-10Nb-10Cr porous alloy was fabricated for highly effective high-temperature flue gas purification. Benefited from microstructural changes and the formation of two new phases, the Ti-40Al-10Nb-10Cr porous alloy demonstrated favorable high-temperature anti-oxidation performance with the incorporation of Nb and Cr high-temperature alloying elements. By the separation of a simulated high-temperature flue gas, we achieved an ultra-high PM-removal efficiency (62.242% for PM and 98.563% for PM>2.5). These features, combined with our experimental design strategy, provide a new insight into designing high-temperature TiAl-based porous materials with enhanced performance and durability.

The effects of Al and Mo elements on the microstructure and hardness of TNM TiAl alloys (Ti-43.5Al-4Nb-1Mo-0.1B) were studied by decreasing 0.5 at.% Mo and/or increasing 1.5 at.% Al. The results showed that the changed composition of the alloy had a slight influence on the morphology, but had important effects on the volume fraction, size, and composition of each phase. All the alloys had nearly full lamellar (NL) microstructures, with a few βo phases at the boundaries of the colony or in the lamellar colony. The lamellar colony size and the lamellar spacing increased with the decrease in Mo and the increase in Al. The reduction in Mo content reduced the content of each phase in proportion, but the increase in Al content in the alloys led to the corresponding increase in Al content in the α2 and γ phases. The hardness of the alloys decreased with the increase in Al content and the decrease in Mo content. This is mainly due to the increase in lamellar spacing caused by the change in composition. Therefore, the increased content of Al and decreased Mo content are unbeneficial for the microstructure. The relationship between the Vickers hardness and the lamellar spacing obeyed the Hall–Petch relationship.

The 8Nb isopleth section of a Ti-Al-Nb system is experimentally determined based on thermal analysis and thermodynamic calculation methods to obtain the phase transformation and equilibrium relations required for material design and fabrication. The phase transus and relations for the 8Nb-TiAl system show some deviations from the calculated thermodynamic results. The ordered βo phase transforms from the disordered β/α phases at 1200–1400 °C over a large Al concentration range, and this transformation is considered to be an intermediate type between the first- and second-order phase transitions. Moreover, the βo phases are retained at the ambient temperature in the 8Nb-TiAl microstructures. The ωo phase transforms from the highly ordered βo phase, rather than from α2 or βo with a low degree of atom ordering B2 (LOB2) structure, with Al concentration of 32–43 at% at approximately 850 °C. From the experimental detection, the transition of the ωo phase from the βo phase is considered to be a further ordering process.

The element distribution and the microstructures of directionally solidified ingots of Ti-45Al-8Nb and Ti-46Al-8Nb alloys were studied by scanning electron microscope (SEM) and electron probe microanalyzer (EPMA) equipped with wavelength-dispersive X-ray spectroscope (WDS). At high solidification rates, e.g., more than 50 μm/s, the ingot solidified in columnar β dendrites, while at low solidification rates, e.g., less than 30 μm/s, the solidification path changed from initial β solidification to L + β→α peritectic solidification, forming cellular dendrites with the β phase matrix surrounded by the α phase. The difference of Ti content in dendritic arms and interdendritic regions was not pronounced. The composition segregation was mainly caused by the mutual conversion of Al and Nb contents. Therefore, it was difficult to distinguish the variation of Ti in microstructure by EPMA-WDS map and line profiles. The composition of the peritectic α phase was different from that of the α phase transformed directly from the β phase. The Al content of the former was about 1 at% higher than that of the latter, while the Nb content was about 1 at% lower. The change of solidification path in the final solidified part resulted from the more severe segregation caused by slow solidification.

Hot isostatic pressing (HIP) and subsequent heat-treatments (HT) are necessary for titanium aluminide (TiAl) casting components. But there are few studies carefully comparing the microstructure changes from the initial as-cast condition to the final heat-treated condition. In this study, the microstructures of Ti-47Al-2Cr-2Nb (at%) alloy in the as-cast, as-HIPed and as-heat-treated conditions were characterized by optical microscopy and scanning electron microscopy. The mechanical properties after HTs were determined by the tensile tests at 700 °C. The results show that after HIP and HTs, all the microstructures exhibit a nearly lamellar (NL) structure and can be divided into an edge region and a central area. The microstructure after HIP in the edge region is normal, while distorted lamellae and many fine recrystallized grains exist in the central area. The yield strengths after three HTs are nearly the same, but the elongation after the HT at 1310 °C is much more than that after HTs at 1185 °C and 1280 °C. A refinement of colony size induced by distorted lamellae in as-HIPed condition is considered responsible for the great improvement in elongation.

Nano-Y2O3 reinforced Ti-47.7Al-7.1Nb-(V, Cr) alloy was fabricated by a powder metallurgy route using spark plasma sintering (SPS), and the influence of nano-Y2O3 contents on the microstructure and mechanical properties were investigated systematically. The results revealed that the ultimate tensile strength and elongation of the alloy were 570 ± 28 MPa and 1.7 ± 0.6% at 800 °C, 460 ± 23 MPa and 6.1 ± 0.4% at 900 °C with no nano-Y2O3, 662 ± 24 MPa and 5.5 ± 0.5% at 800 °C, and 466 ± 25 MPa and 16.5 ± 0.8% at 900 °C with 0.05 at% nano-Y2O3 addition, respectively. Due to the fine-grain strengthening and the second-phase strengthening, both tensile strength and elongation of the high-Nb TiAl alloy were enhanced with the addition of nano-Y2O3.

Abstract There is widespread attention to surface profile and modification of 304 stainless steel for research development and application. Here, a successful electrolytic plasma processing (EPP) technique has been developed for both surface pretreatment and coating deposition of 304 stainless steel. Representative images confirm that the number of the pits increases and the ravines gradually disappear on the steel pretreated by EPP with the increase of processing time and applied voltage. Moreover, there is an obvious enhancement in surface roughness of 304 stainless steel after EPP pretreatment. In the case of coating deposition, the further EPP modification conducted on the pretreated sample offers a simple and effective technique for the production of zinc coatings having the features of full coverage and homogeneous distribution. The results show that a zinc coating with a thickness of approximately 0.5 μm can be obtained on the 304 stainless steel by means of EPP for only 60 s.

High Nb-containing TiAl alloys have good oxidation resistance and mechanical properties, but the microstructure and the properties are substantially affected by the segregation. To quantitatively investigate the segregation behavior of Al during solidification, microstructures of directionally solidified (DS) Ti-45Al-8Nb (in atomic percent) alloy prepared at withdrawing rates of 30 μm/s and 200 μm/s and a temperature gradient of 4200 K/m were observed by optical microscope and electronic probe microanalyzer. The microsegregations were characterized by wave dispersive spectroscopy. The results show that the DS ingots include the no melting zone, directionally solidified zone with columnar grains, mushy zone, and quenched liquid zone. The primary dendritic arm spacings are 353 μm and 144 μm, respectively, for the two ingots. But the solidified microstructures of the ingots are large lamellar colonies, which contain a few B2 patches and γ bands induced by microsegregation. From dendritic zone to columnar zone, the volume fractions of B2 patches and γ bands decrease. The segregation extents of Al and Nb decrease with the increase of solidification rate. There exists an obvious back diffusion process of Al during solidification and cooling after solidification. According to evolution of Al concentration profiles from mushy zone to columnar grain zone, interdiffusion coefficient for Al in β-Ti at near solidus temperature is semiquantitatively calculated, and the value is (6 – 11) × 10−11 m2/s.

The friction weldability of Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y alloy has been investigated by optimizing process parameters and analyzing the microstructures and tensile properties of the joints. The as-cast alloy with a nearly lamellar (NL) microstructure and the as-forged alloys with a duplex (DP) microstructure have been successfully welded. All the joints have a severe deformation zone (SDZ) and a transition zone (TZ) between the parent metal (PM) and SDZ. SDZ, showing a biconcave lens geometry, has a maximum thickness of hundreds of micrometers at the periphery. TZ is hundreds of micrometers thick. All SDZs have a fine-grained DP microstructure with a grain size of a few micrometers. For the joint of the as-cast alloy, the TZ consists of deformed lamellar colonies as the major constituent and partially recrystallized grains as the minor constituent. For the joint of the as-forged alloy, the TZ is similar to both the PM and SDZ, showing a DP microstructure. The grain size, volume fraction of γ grains, and the remnant lamellar colonies all increase with the distance from the SDZ. All joints presented perfect metallurgical bonding. The strengths of the joints are higher than those of the corresponding PMs. This indicates that the studied alloy has good friction weldability.

In this study, we applied an emerging, environmentally friendly surface engineering technology, electrolytic plasma processing (EPP), for the surface modification of Q195 structure carbon steel surface pretreatment and further Zn coating. Treating the surfaces of Q195 structure carbon steel by EPP was a quite dynamic process, which was investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results shown that surface scale can be effectively remove after 40 s EPP treatment, and the EPP-treated Q195 structure carbon steel revealed a slight decrease in elastic modulus and hardness, but a substantial improvement in tensile (especially plastic) mechanical properties. Moreover, the further EPP modification conducted on the pretreated Q195 structure carbon steel sample for production of a layer of compact zinc coating with 15 μm thickness under an optimization EPP process. We also identified the modification mechanism of EPP to Q195 structure carbon steel, which may provide theoretical and practical guidance for future researchers and developers.

Al2O3 coatings were prepared on Ti-45Al-8.5Nb alloys via cathodic plasma electrolysis deposition (CPED) in both 1.2 M Al(NO3)3 aqueous and ethanolic solutions. Different voltages were also applied during the deposition process to optimize coating properties. Coatings deposited in both solutions mainly consisted of γ-Al2O3, with some Al(OH)3 found in coatings prepared in aqueous solution. Coatings prepared in ethanol solution exhibited better oxidation resistance at 900 °C as well as better substrate adhesion, which was mainly due to smaller crater sizes on coating surfaces. The deposition process was discussed in detail and the reason for the smaller craters examined. The results suggested that solution surface tension mainly influenced the average diameter of hydrogen bubbles that formed on cathode surfaces during the process. Smaller bubbles lead to both lower current densities on cathodes and smaller crater sizes on coatings.

Ultra-thin Fe-6.5 wt. % Si ribbons of 35 μm in thickness were prepared by melt-spinning. The magnetic properties were investigated before and after annealing at 1000 °C. The DC properties and low-frequency (400 Hz~10 kHz) iron losses significantly improved after heat treatment. A simplified formula— P t = k t B m N —based on the Steinmetz law, which can be used to predict the AC iron loss, is presented. The symbols “kt” and “N” are defined as functions of microstructure and frequency. According to the tested results of iron loss, the values of “kt” and “N” can be fitted and therefore the simplified formula can be determined. The extent of AC iron losses can be predicted according to the formula. The results obtained from the formula predict AC iron loss to a good degree. The method developed in this work could be extended to other magnetic materials for predicting AC iron loss with greater ease.

The flow behavior of Fe-6.5wt. %Si alloys during hot compression was investigated at temperatures 650–950 °C and strain rates 0.01–10 s−1. The results showed that the flow stress depended distinctly on the deformation temperatures and strain rates. The flow stress and work hardening rate increased with the decrease of temperature and the increase of strain rate. The activation energy under all the deformation conditions was calculated to be 410 kJ/mol. The constitutive equation with hyperbolic sine function and Zener–Hollomon parameter was developed. The peak stress, critical stress, and steady-state stress could be represented as σ = A + Bln(Z/A). Dynamic recrystallization occurred under the deformation conditions where the values of Z were lower than 1020. Processing maps were established to optimize the processing parameters. The power dissipation efficiency decreased in the high temperature and low strain rate region, increased in the high temperature and high strain rate region, and remained unchanged in other regions with the increase of true strain. Furthermore, the unstable area expanded. The true strain of 0.7 was the optimum reduction according to the processing map. Based on the analysis of surface quality, microstructures, and ordered structures, the optimized processing parameters for the Fe-6.5wt. %Si alloys were the temperature and strain rate of higher than 900 °C and 0.01–10 s−1, respectively, or 800–900 °C and lower than 0.4 s−1, respectively.

Due to its excellent glass-forming ability (GFA), the Zr48Cu36Al8Ag8 bulk metallic glass (BMG) is of great importance in glass transition investigations and new materials development. However, due to the lack of detailed structural information, the local structure and atomic packing of this alloy is still unknown. In this work, synchrotron measurement and reverse Monte Carlo simulation are performed on the atomic configuration of a Zr-based bulk metallic glass. The local structure is characterized in terms of bond pairs and Voronoi tessellation. It is found that there are mainly two types of bond pairs in the configuration, as the body-centered cubic (bcc)-type and icosahedral (ico)-type bond pairs. On the other hand, the main polyhedra in the configuration are icosahedra and the bcc structure. That is, the bcc-type bond pairs, together with the ico-type bond pairs, form the bcc polyhedra, introducing the distortion in bcc clusters in short range. However, in the medium range, the atoms formed linear or planar structures, other than the tridimensional clusters. That is, the medium-range order in glass is of 1D or 2D structure, suggesting the imperfect ordered packing feature.