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This study investigates the effect of cerium on the microstructures, mechanical properties of medium carbon Fe-B cast alloy. The as-cast microstructure of Fe-B cast alloy consists of the eutectic boride, pearlite, and ferrite. Compared with the coarse eutectic borides in the unmodified alloy, the eutectic boride structures in the modified alloy are greatly refined. Cerium promotes the formation of CeO phase. CeO can act as effective heterogeneous nuclei of primary austenite, and refine austenite and boride. After heat treatment, the impact toughness of the modified alloy is higher than that of the unmodified alloy because there are more broken borides in the modified alloy. Meanwhile, the fracture mechanism of medium carbon Fe-B alloy is depicted and analyzed by using fractography. [ABSTRACT FROM AUTHOR]

In order to improve the room temperature ductility and high temperature strength of Fe-25Al alloys, in situ 20 wt.%AlO/Fe-25Al composites with 0, 1, 2, 3, 4, and 5 at.% Cr element contents (0-6.70 wt.%) were prepared by mechanical alloying inducing self-propagating reaction with subsequent plasma-activated sintering. Microstructures, room temperature hardness, flexural strength, fracture toughness, and compression property and wear behavior at mid-high temperatures of the sintered samples were tested and analyzed. The results showed that all the composites with Cr element addition had good microstructure with fine grain size and high relative density. The flexural strength and fracture toughness increased first and then decreased with increasing content of Cr. Especially, the composites with 3 at.% Cr had the highest flexural strength, highest fracture toughness, and best compressive properties during 298-1073 K, and the main fracture mechanism changed from brittle fracture at room temperature to plastic deformation and pullout of the second phase at 673 K. With Cr content increasing, the friction coefficients decreased and the wear rates increased because of decreasing hardness. The composites with 3 at.% Cr had excellent wear properties with lower friction coefficient and wear rate. [ABSTRACT FROM AUTHOR]

Abstract: Bulk Cr7C3 compounds were fabricated with Cr and C mixed-powder by mechanical ball milling and plasma activated sintering (PAS). The results indicate that, there is no alloying reaction between Cr and C powders at milling times from 3h to 15h; at milling times from 1h to 7h, the morphology of mixed-powder becomes finer and the distribution becomes more and more uniform; however, as milling time exceeds 7h, the morphology and distribution have no obvious change. At sintering temperature of 1648K for 2h duration, there is also Cr23C6 compound besides Cr7C3. With sintering temperature reaching 1673K and above, the single bulk Cr7C3 compound can be fabricated; however, the cracks appear at 1698K. The result also indicates that, as sintering time increases from 2h to 4h at 1673K, the relative density of bulk Cr7C3 will increase; however, as the sintering time exceeds 4h, the density has no obvious change. Furthermore, the hardness of bulk Cr7C3 increases slightly with sintering time. The bending strength and fracture toughness increase with the sintering time changing from 2h to 4h; however, they decrease slightly with the time exceeding 4h. [Copyright &y& Elsevier]

Highlights: [•] The as-received microstructure of bulk Fe2B comprises iron and silicon borides. [•] The orientation of Fe2B in liquid zinc strongly affects on corrosion resistance. [•] The Fe2B/FeB phase transition process of bulk Fe2B in liquid zinc occurs. [•] Phase transition and spalling dominate corrosion of Fe2B in liquid zinc. [Copyright &y& Elsevier]

The tribological properties of Fe3Al-20 wt% Al2O3 composites, prepared by means of mechanical alloying and plasma-activated sintering, were investigated under air atmosphere against GCr15 bearing steels from room temperature to 500 °C. It was found that the friction coefficient of the composites (at 200 °C/350 °C) decreased with increasing temperature and the value was lower than that of Fe3Al alloys at the same temperature, and the friction coefficient increased again at 500 °C. Moreover, the wear rates of all the pins and discs were low at the medium/high temperatures. The dominant wear mechanism of the composites is microplowing and a little oxidation wear at room temperature. However, at elevated temperatures, oxidation wear and a little microplowing are found to be the main wear mechanism. There is also spalling induced by microfracture at 500 °C. The in situ Fe3Al-20 wt% Al2O3 composites have excellent wear resistance at a wide temperature range. [ABSTRACT FROM AUTHOR]

• Mo reacts with dissolved oxygen and Pb in liquid LBE to produce a multilayer film. • The dissolved oxygen firstly oxidizes the surface of Mo into a nano-structured MoO 2. • An ultra-fined PbMoO 4 forms on MoO 2 , and its outer side can grow into columnar grains. • The columnar PbMoO 4 can be further oxidized into blocky Pb 2 MoO 5 layer. The oxidation mechanism of refractory Molybdenum exposed to oxygen-saturated lead-bismuth eutectic (LBE) at 600 °C was investigated. The results show a hierarchical structure of multiple corrosion layers. Specifically, a nanostructured tetragonal MoO 2 is the first scale that forms on the Mo substrate, followed by development of an ultrafine-grained tetragonal lead molybdate (PbMoO 4) layer. On the top of this ultrafine-grained layer, there is a thicker scale that consists of micron-sized columnar PbMoO 4 and its upper part can be further oxidized into blocky monoclinic-structured Pb 2 MoO 5. The formation of these multilayered scales is likely predominated by inward diffusion of oxygen and Pb. [ABSTRACT FROM AUTHOR]

The effect of Si and prolonged time on interfaces and cavitation erosion behavior of directionally solidified (DS) Fe-B alloy in flowing liquid zinc was investigated. The results show Si enriches in α -Fe intragranular and α /Fe 2 B boundaries to refine textured grains. DS Fe-B alloy with 2.5 wt%Si exhibits the best cavitation erosion resistance to flowing zinc, which is attributed to formation of alternating distributed Γ -Fe 3 Zn 10 and FeSi and subsequently columnar ζ -FeZn 13. Cavitation erosion resistance mechanism of DS Fe-B alloy with 2.5 wt%Si is manifested that Si-induced Γ -Fe 3 Zn 10 and FeSi and the rooting-whisker ζ -FeZn 13 layer can inhibit spallation and cracks of Fe 2 B and products. • DS Fe-B alloy with 2.5 wt%Si in large high-velocity flowing liquid zinc exhibits the best cavitation erosion resistance owing to unique interfacial product films. • Si segregation promotes the formation of innermost alternating distributed Γ -Fe 3 Zn 10 and FeSi and the subsequent orderly arranged columnar ζ -FeZn 13 layer in flowing liquid zinc. • There exists a possible orientation relationship of (14−1) Fe3Zn10 // (13−2) FeSi at innermost interfaces of DS Fe-B alloys containing Si in flwoing liquid zinc. • Cavitation erosion resistance of DS Fe-B alloys depends on synergies of FeSi/Γ and ζ -FeZn 13 layer to inhibit the spallation of oriented Fe 2 B and product films at interfaces. [ABSTRACT FROM AUTHOR]

The present study investigates the influences of SiC incorporation on the microstructure and corrosion behavior of B4C–nSiC composites in molten FLiNaK salt at 800°C. The corrosion characteristics and mechanisms of B4C–nSiC composites in molten FLiNaK salt were thoroughly characterized and extensively discussed. The B4C–nSiC composites exhibited a more refined grain size and lowered apparent porosity as the SiC content increased. Additionally, the concentration of high‐angle grain boundaries (HAGBs) in B4C–nSiC composites increased as the SiC content increased. The incorporation of 10 wt.% SiC improved the corrosion resistance of B4C–nSiC composites against molten FLiNaK salt. However, the incorporation of excessive SiC (≥20 wt.%) did not improve the corrosion resistance. The best corrosion resistance of B4C–10% SiC ceramic composite was attributed, on the one hand, to its relatively low apparent porosity and the low concentration of HAGBs with high structural disorder. On the other hand, the selective corrosion of B4C in B4C–10% SiC ceramic composite rapidly formed a sufficiently thick and highly graphitized C‐rich layer on its surface during the initial stages of the corrosion test. The C‐rich layer maintained the integral structure of the ceramic and prevented subsequent corrosive medium from penetrating into the ceramic. [ABSTRACT FROM AUTHOR]

The effect of Fe 2 B orientation in Fe–3.5 wt.% B steel on its erosion–corrosion behavior in 460 °C flowing zinc was investigated. The results indicate that the erosion–corrosion resistance of Fe–3.5 wt.% B steel relies strongly on Fe 2 B orientation. The orientation of Fe 2 B determines the erosion–corrosion interface, which governs the diffusion, interfacial reaction, failure mode of Fe 2 B, and significantly influences the erosion–corrosion behavior. The strong pinning effect of corrosion products and columnar Fe 2 B suppresses erosion–corrosion; this suppression results in good erosion–corrosion resistance to liquid zinc of the Fe–3.5 wt.% B steel with the [0 0 2] direction of Fe 2 B perpendicular to the erosion–corrosion interface. [ABSTRACT FROM AUTHOR]

A novel micro-nano-structured Cr 3 C 2 –NiCr cermet coating was prepared on 316L stainless steel by high-velocity oxygen fuel spraying technology (HVOF). Cermet coatings with different contents of micro-and nano-sized Cr 3 C 2 particles as the hard phase and a NiCr alloy matrix as the bonding phase were prepared and characterized in terms of porosity, microhardness, and corrosive wear resistance in a 3.5% NaCl solution and artificial seawater. Compared to nanostructured coatings, micro-nano-structured coatings avoid decarburization and reduce nanoparticle agglomeration during the spray process, and mechanical and electrochemical properties were improved in comparison with those of conventional coatings. The micro-nano-structured Cr 3 C 2 –NiCr coating rendered low porosity (≤0.34%) and high microhardness (≥1105.0HV 0.3). The coating comprising 50% nano-sized Cr 3 C 2 grains exhibited the best corrosive wear resistance owing to its densest microstructure and highest microhardness. Furthermore, compared to static corrosion, the dynamic corrosion of the coatings led to more severe mechanical wear, because corrosion destroyed the coating surface and ions promoted corrosion to invade coatings through the pores during corrosion wear. [ABSTRACT FROM AUTHOR]

Abstract: Fe3Al–20wt.%Al2O3 ultrafine grained composites with 4wt.% Cr were prepared by mechanical alloying inducing self propagating high temperature synthesis with subsequent plasma activated sintering. Microstructures of the composites were studied by X-ray diffraction, scanning electron microscopy, energy dispersive spectrum and transmission electron microscope. Then the relative density, room temperature hardness, static corrosion resistance and dry sliding wear behavior at a temperature range of 25°C–800°C of the sintered samples were tested and analyzed. The results showed that the composites had high hardness and a good microstructure with fine grain size, high relative density. The composites with 4wt.% Cr amount also exhibited excellent comprehensive tribological properties at medium–high temperatures especially at a temperature above 500°C, although the wear resistance did not be improved at 25°C–500°C. 4wt.% Cr element addition improved the corrosion resistance of the composites significantly with the corrosion loss decreasing by 19.48%. [Copyright &y& Elsevier]

This work aims to elucidate the microstructure characteristics of each phase in carbidic austempered ductile iron and the nucleation and growth of acicular ferrite in an austempering temperature range of 250–450 °C. The research results showed that the carbides (Fe, Cr)3C obtained by the eutectic reaction had high indentation hardness and indentation modulus, and the interface between acicular ferrite and eutectic carbides belonged to incoherent boundary. Since the nucleation driving force of acicular ferrite increased with an increase in temperature difference (ΔT), the size of acicular ferrite gradually decreased with the decrease in isothermal temperature. When the austempering temperature was above 400 °C, acicular ferrite preferentially nucleated around the graphite nodules and inside grains. However, acicular ferrite preferentially nucleated around the graphite nodules and the eutectic carbides at temperature below 400 °C. Additionally, a fine twin structure had been found inside some acicular ferrite after austempering at a low temperature (250 °C). [ABSTRACT FROM AUTHOR]

The article studies on the effect of slippage rate on frictional wear behaviors of high-tungsten high-speed steel (HTHSS) under high-pressure contact by using a self-made ring-on-ring wear machine. The microstructure of HTHSS is characterized by dual-scale tungsten carbides, including microscale eutectic M 6 C carbide [(Fe 0.55 W 0.30 Cr 0.08 Mo 0.07) 6 C] and nanoscale secondary M 6 C carbide. Slippage rate has a significant effect on frictional wear behaviors. The peak value of friction coefficient occurs at the slippage rate of 5.5%. The friction coefficient will reduce whether the slippage rate increases or decreases. However, the increase in slippage rate makes wear failure mechanism change from fatigue to scratch, causing continuously significant increase in wear weight loss. The roles of different scale M 6 C carbides in resisting wear were also discussed. Image 1 • Sliding-rolling frictional wear behaviors of HSS with micro-nano scales M 6 C were studied. • Slippage rate decides wear failure mode and therefore affects wear property of HSS. • High stress contact caused martensite transformation, contributing in delaying wear failure. • Micro-nano scales M 6 C play a different role under different slippage rate. [ABSTRACT FROM AUTHOR]

• Temperature effect on oxidation resistance of a Fe-Cr-B-Al-C-Mn-Si alloy is studied. • The oxidation resistance is best at 900 °C; it decreases with rising temperature. • The formation mechanism of oxide scale with bilayer/monolayer structure was discussed. • MnCr 2 O 4 oxides promote protective α-Al 2 O 3 oxide formation. • Selective oxidation of Al suppresses outward diffusion of Cr and Mn. The effect of temperature on the oxidation resistance of a novel wear-resistant Fe-10Cr-1.5B-6Al-0.3C-0.8Mn-0.6Si alloy is investigated. The mass growth rate shows that this alloy exhibits superior oxidation resistance at 900 °C. As the oxidation temperature increases from 900 °C to 1100 °C, the structure of the observed oxide scales transforms from a porous bilayer to a flat monolayer, while the oxidation rate increases sharply. The selective oxidation of Al suppresses the outward diffusion of Cr and Mn to form MnCr 2 O 4 oxides in the monolayer oxide scale, thereby decreasing the oxidation resistance at 1100 °C. [ABSTRACT FROM AUTHOR]

Highlights • Effects of Al concentration on the formation of inhibition layer (IL) are studied. • Both experiments and mesoscopic simulations are conducted. • Dynamic evolutions of IL structure and concentration fields are discussed. • Results show that higher Al concentration accelerates IL growth. • IL thickness increases with Al concentration. Abstract The formation of inhibition layer (IL) during hot-dip galvanizing with Al concentration varying from 0.0 to 0.8 wt pct. is studied by both experiments and numerical simulations. Using EDS and XRD, the IL is identified mainly as Zn-bearing Fe 2 Al 5. SEM results reveal that the IL thickness increases with Al concentration in zinc bath, and the particles of Fe 2 Al 5 on the surface of IL formed in 0.8 wt pct. Al bath are smaller than those formed in 0.2 wt pct. Al bath. On the surface of IL generated in 0.8 wt pct. Al bath there are some tiny particles with size about tens of nanometers randomly dispersing on the larger ones, indicating that the growth of IL is so fast that the growth mode changes and nucleation occurs at the IL/zinc interface. Using a mesoscopic model based on the lattice Boltzmann method, numerical simulations are also performed to study the reactive transport phenomena during IL formation under different Al concentrations. The simulations reveal complex coupled mechanisms between Fe and Al diffusion, Fe dissolution, as well as nucleation and growth of Fe 2 Al 5 and the results agree with the experiments. [ABSTRACT FROM AUTHOR]

• Thermally induced precipitation was firstly proposed for FePO 4 recovery from ISSA. • The leachate successfully recycled for five times to recover FePO 4 precipitates. • A high phosphorus recovery rate of 81.1 ± 1.8% was achieved from sludge leachate. • Low cost of ∼$26.9/kg-P was achieved for recovering phosphorus from ISSA. • The FePO 4 precipitates were used to promote plant growth and synthesize LiFePO 4. Phosphorus recovery from incinerated sewage sludge ash (ISSA) is important but hindered by low selectivity. Here, a novel strategy of acid leaching followed by thermally induced precipitation was proposed for the efficient and selective recovery of FePO 4 from ISSA samples. A high phosphorus leaching efficiency of ∼ 99.6% was achieved with 0.2 mol/L H 2 SO 4 and liquid to solid (L/S) ratio of 50 mL/g. Without removing various co-existing ions (Al3+, Ca2+, SO 4 2–, etc.), high-purity FePO 4 of ∼ 92.9% could be facilely produced from this highly acidic H 2 SO 4 leachate (pH = 1.2) by simple addition of Fe(III) at a molar ratio of 1:1 to the phosphorus and reacted at 80 °C for thermally induced precipitation. The remained acid leachate could be further reused for five times to continue leaching phosphorus from the ISSA samples and produce the FePO 4 precipitates with a high phosphorus recovery efficiency of 81.1 ± 1.8%. The selective recovery of FePO 4 from the acid leachate was demonstrated more thermodynamically favorable compared to other precipitates at this acidic pH of 1.2, and elevated temperature of 80 °C towards thermally induced precipitation. The estimated cost of this strategy was ∼$26.9/kg-P and lower than that of other existing technologies. The recovered FePO 4 precipitates could be used as a phosphate fertilizer to promote the growth of ryegrass, and also as a precursor to synthesize high-value LiFePO 4 battery material, demonstrating the high-value application potential of the phosphorus from the ISSA. [Display omitted] [ABSTRACT FROM AUTHOR]

The microstructure and oxidation behavior of Fe–B alloys have been investigated. Oxide scale cross-sectional microstructures oxidized at 1073 K for 100 h have been studied. EPMA investigations show that B 2 O 3 –SiO 2 oxides accumulates in the inner oxide layer which improves the oxidation behavior and oxide layer adhesion considerably. Cyclic oxidation kinetics data indicates that Fe–B 3.08 wt.% alloy presents the best oxidation resistance. The formation of diffusion zone in the Fe–B alloys indicate that the oxidation of the Fe 2 B boride is controlled by boron diffusion. The diffusion zone increases with time and reaches a maximum width of 60–65 μm. [ABSTRACT FROM AUTHOR]

Abstract: In-situ 20 wt.%Al2O3/Fe–25Al composites were prepared by mechanical alloying (MA) inducing self-propagating reaction (SHS) with subsequent plasma activated sintering (PAS). The density and hardness of the composites were 99.2% and 56.9 HRC, respectively. The tribological properties of 20 wt.%Al2O3/Fe–25Al composites under dry sliding against GCr15 bearing steels from room temperature to 773 K in argon atmosphere were investigated. The results show that the friction coefficients of 20 wt.%Al2O3/Fe–25Al composites are in the range of 0.47–0.88 at the given testing conditions, and they decrease with increasing temperature at first, then increase again at 773 K. Similarly, the wear rates of Al2O3/Fe–25Al composites are much lower than that of Fe–25Al alloys. The wear rates of the composites are higher at room temperature but dramatically decrease with increasing temperature. At 773 K, the wear rates of the composites and the counterpart GCr15 bearing steel disk are on the order of 0.03 (10−3 mm3/Nm). The dominant wear mechanism of 20 wt.%Al2O3/Fe–25Al composites is microploughing with a little oxidation wear and adhesive wear at room temperature. The main wear mechanism is transferred to adhesive wear with increasing temperature, especially at 773 K, the wear mechanism is mainly adhesive wear. [Copyright &y& Elsevier]

Abstract: The mixed powders of in situ Al2O3 particles and Fe (Al) solid solution were prepared via self-propagating combustion reaction initiated by mechanical alloying (MA), and the MA mechanism of several Fe2O3–Al–Fe systems with different Al2O3 mass fractions were studied. The adiabatic temperature (T ad) of each system was calculated to estimate whether the self-propagating combustion reaction could be initiated in theory. The microstructure of the mixed powders was investigated by SEM, EDS and TEM. The phase analysis was evaluated by XRD, and the Fe lattice parameter was calculated from the XRD patterns. The results showed that with the addition of Fe during the MA process, the activation period was prolonged and the sharp increase of temperature occurred, and when the Al2O3 mass fraction was decreased to 10.94%, the self-propagating combustion reaction could not occur in theory and practice. When there was no added Fe, the final product was homogeneous Fe (Al) solid solution. [Copyright &y& Elsevier]

Abstract: Fe3Al–20wt.%Al2O3 ultrafine grained composites were prepared by mechanical alloying (MA) with subsequent plasma activated sintering (PAS). Microstructures of the Fe3Al–20wt.%Al2O3 composites and Fe3Al alloys were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrum (EDS) and transmission electron microscope (TEM). Then the relative density, room temperature hardness and compression property at 25–800°C of the sintered samples were tested and analyzed. The results showed that Fe3Al–20wt.%Al2O3 composites sintered at 1100°C had fine grain size, high relative density, high hardness and excellent microstructure. The sharp drop in strength of Fe3Al alloys above 600°C was improved via introducing 20wt.%Al2O3 although the plastic toughness and strength at 25–400°C of the composites was lower than Fe3Al. [Copyright &y& Elsevier]

Abstract: The ground state properties of eta M3W3C (M=Fe, Co, Ni) compounds are discussed in this paper. The characteristics of chemical bonding and full set of elastic constants were calculated by first-principles calculations. The calculated formation enthalpy values indicate that they are thermodynamically stable structures. The Fermi surface is dominated by d bands of W and M, and the whole structures have metallic nature. The calculated bulk modulus values range from 338.6 to 376.9GPa, larger than Fe3C, Fe2B, and Cr7C3. The population analysis reveals the attractive interactions for M3W3C are dispersed in the whole crystals. [Copyright &y& Elsevier]

The interfacial microstructure and corrosion behavior of oxide dispersion strengthening (ODS) FeCrAl alloy with 20 wt% Cr (e.g. 20Cr ODS FeCrAl alloy) exposed to static oxygen-saturated lead-bismuth eutectic (LBE) at 450 °C for 20 h, 40 h, 60 h, 80 h and 100 h as exposure time respectively have been investigated. The results show that multilayer corrosion films of 20Cr ODS FeCrAl alloy can exist at the corrosion interface. Due to formation of protective scales, the primary corrosion mechanism of 20Cr ODS FeCrAl alloy in LBE is oxidation rather than dissolution and penetration of liquid LBE. Specially, the spinel-shaped nano-sized dense external layer without any microcracks is obviously observed. Moreover, the dense and compact scale with micron-meters, i.e. Al-rich Fe-Cr spinel, generates at interface as the middle layer to effectively defend inward diffusion of oxygen and penetration of LBE. Meanwhile, a reinforced and continuous internal layer mixed with Cr 2 O 3 scale and the ferrite inner oxidation zone (IOZ) existing in the form of the interlocking interface between the layers and the substrate can further promote the adhesion between corrosion layers and the substrate of 20Cr ODS FeCrAl., (© 2024. The Author(s).)