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The responses of the impact strength and structure of bisphenol A polycarbonate (PC) to aging in a 5 wt% aqueous solution of NaCl were studied in detail. The results of the Izod notched impact test showed that the impact strength decreased from 71.1 kJ/m2 to 17.5 kJ/m2 after an aging time of only 1 day in the aqueous solution of NaCl. The surface appearance of the aged PC observed by polarizing optical microscopy indicated that a large number of microvoids formed, and the size and number of these microvoids increased substantially with an increase in the aging time. The glass transition temperature, measured by differential scanning calorimetry, underwent a slight decrease after aging in the NaCl solution. In addition, no crystallization could be inferred from the heating curves. Thermal gravimetric analysis showed that the thermal decomposition temperature moved to a lower temperature, and the changes of the NaCl solution pH values indicated that hydrolysis was the dominant mechanism of degradation during aging in the aqueous solution of NaCl. Furthermore, the presence of NaCl accelerated the hydrolysis during the early stages of aging. A ductile-brittle transition caused by aging was inferred from observations of fracture surfaces using scanning electron microscopy. [ABSTRACT FROM AUTHOR]

To evaluate the enhanced erosion wear performance under acidic medium, a new high-vanadium–chromium alloy (HVCA) is designed and test samples produced by sand casting. The microstructure was analyzed by SEM, TEM and XRD. The erosion wear performance was tested in acidic medium designed by orthogonal test method. The factors affecting the erosion wear performance of HVCA are analyzed. The research results show that microstructure of HVCA is characterized by different carbides (M7C3, M23C6, VC, M2C) distributed in martensite and residual austenite. The hardness is 65.16 ± 0.2 HRC, and the impact toughness is 9.82 ± 0.12 J/cm2. H2SO4 concentration has the greatest influence on the erosion wear performance of HVCA, followed by the erosion wear angle. The maximum erosion wear performance of HVCA is 1.59 times that of HCCI. Compared with HCCI, HVCA has excellent erosion wear resistance because of its high hardness and toughness, a small amount of fracture and carbide shedding, and slight corrosion and wear interaction under erosion wear condition. [ABSTRACT FROM AUTHOR]

Medium/High entropy alloys (M/HEAs) based on the FeCoNi system have gained significant attention due to their outstanding magnetic and electrical properties. In this study, the FeCoNiZr x (x = 0, 0.2, 0.4, 0.6, 0.8, 1) MEA films were prepared using the magnetron sputtering method. The effect of Zr on the structure and soft magnetic properties is studied. As the Zr content increases, the films transform from the face-centered cubic (FCC) phase to the amorphous phase. This study shows that FeCoNiZr 0.4 film exhibits excellent combined properties, including a high magnetization saturation (Ms) of 1127.8 emu/cm3, a minimum coercivity (Hc) of 0.96 Oe, and a high resistivity of 147 μΩ·cm, which is superior to the Permalloy and soft magnetic materials reported in other articles. Combined structural analyses show that the FeCoNiZr 0.4 film has the finest particle size, amorphous structure, and continuous and uniform magnetic domains, decreasing the pinning effect on magnetic domains. These results enhance the magnetic properties of FeCoNiZr 0.4 film. • The soft magnetic FeCoNiZr x medium entropy alloy films were developed. • The Zr lead to the transition from FCC phase to amorphous in the FeCoNiZr x films. • The formation mechanism of the amorphous films was analyzed by the AIMD simulation. • The FeCoNiZr 0.4 amorphous film showed the best comprehensive performance. [ABSTRACT FROM AUTHOR]

Ferro-coke is prepared by the slight coking of coal and iron ore. It is a new type of fuel used for blast furnace ironmaking for the purpose of energy saving and emission reduction. However, with the increase of iron ore content, the metallurgical properties of ferro-coke gradually deteriorate. To fabricate high-strength ferro-coke, coal tar pitch was used as a binder in this study. The microstructure, cold drum strength, thermal crushing strength, gasification reactivity and gasification kinetics of this modified ferro-coke were systematically studied and compared with those of gas-coal coke and ferro-coke without binder. The results showed that the coal tar pitch could reduce the porosity of ferro-coke by 4.57 pct, enhance the adhesion of carbon matrix to minerals and increase the microcrystalline structure of ferro-coke. The cold drum strength of ferro-coke increased from 28.04 to 86.34 pct after adding coal tar pitch, while the thermal strength of ferro-coke during the gasification process rose by only 100 N. The coal tar pitch had little effect on the gasification reactivity of ferro-coke, so the activation energy of modified ferro-coke was still low. The first-principle calculation results revealed that the promotion of Fe on the ferro-coke gasification was attributed to the reducing role of Fe on the reaction energy of ketone group decomposition. [ABSTRACT FROM AUTHOR]

• High-dose carbon ion implantation improved the corrosion resistance of CSS-42L steel. • Fe 2 C nanocrystals were uniformly precipitated in the implanted matrix. • Amorphization of Cr-rich carbides also occurred in the implanted layer. • The microstructure evolution was responsible for this modification. The precipitation of Cr-rich carbides creates significant chromium depletion zones against the steel matrix, which are more sensitive to pitting corrosion. In this work, high dose carbon ion implantation was introduced to eliminate the negative effect of Cr-rich carbides precipitated in carburized CSS-42L steel. X-ray photoelectron spectroscopy (XPS) analysis reveals the co-existence of graphite bonds and carbide bonds for the carbon implanted samples. Amorphization transformation for Cr-rich carbides and precipitation of nanocrystalline Fe 2 C carbides in the implanted layer are confirmed by transmission electron microscopy (TEM) and glancing incidence x-ray diffraction (GIXRD) investigations. The electrochemical results indicated that the microstructure evolution induced by carbon ion implantation was beneficial in improving the corrosion property of carburized CSS-42L steel, in which the intergranular corrosion was suppressed and the corrosion degree was also modified. [ABSTRACT FROM AUTHOR]

Due to their high hardness, comparable to that of tool steels, as well as other properties, Ni-rich NiTi alloys have recently been considered as a promising alloy system for using in bearing and related applications. The large volume fraction of nanoscale Ni 4 Ti 3 precipitates is the main origin of the high hardness of these alloys. This study investigated the effects of Nb content (1, 3, 5 at.%) on the precipitation and the hardening behavior of the Ni-rich Ni 55 Ti 45 (at.%) alloys. The microstructures of the quenched and aged alloys are mainly composed of B2-NiTi matrix, nanoscale Ni 4 Ti 3 precipitates, and a small amount of Ti 2 Ni and Ni 3 Ti 2 phases, and no Nb-containing phase has been detected. A few R phases are also observed in the Ni 55 Ti 45 base alloy and are eliminated by Nb additions. With the Nb additions, the Ni 4 Ti 3 precipitates transform from lens morphology to block morphology and show enhanced hardness. After aging at 400 °C for 3 h, the hardness increases from 643 ± 12.3 Hv for the base alloy to 745 ± 9.2 Hv for the 5Nb alloy. A linear arrangement of the sphere or ellipsoid Ni 3 Ti 2 particles is also observed in the present alloys, with the number density and size of the Ni 3 Ti 2 precipitates increasing with Nb addition. The present work provides important new insights for creating a novel NiTi-based bearing alloy. [ABSTRACT FROM AUTHOR]

TiAlMoNbWSi x (x = 0, 0.3, 0.5, 0.7) HEA films were deposited by magnetron co-sputtering technology to enhance the wear and high-temperature corrosion resistance of the copper. The structure of films was regulated by changing the content of Si to improve the comprehensive properties. The lattice distortion and negative mixing enthalpy change caused by the introduction of Si transformed the film from BCC structure to amorphous. With the increase of Si content, the wear resistance and the oxidation resistance were effectively improved. The characteristic delayed diffusion effect of HEA film allowed all the TiAlMoNbWSi x films to successfully block the diffusion between Zn and Cu. • The transformation of TiAlMoNbWSi x film structure with variation of Si content was interpreted. • The solution of Si enhances the high-temperature oxidation resistance of TiAlMoNbWSi x film. • Si changes the abrasion mechanism and improves the wear resistance of TiAlMoNbWSi x film. • The relationship of the "microstructure-mechanical properties" and "microstructure-high temperature resistance" is discussed. [ABSTRACT FROM AUTHOR]

The microstructural characterization and mechanical properties of the oil quenched binary Ni 55 Ti 45 alloy and Hf-modified Ni 55 Ti 45-x Hf x (x = 3, 5, 7 at.%) alloys were investigated. The results showed that the microstructure of binary alloy is composed of NiTi phase, nanoscale Ni 4 Ti 3 precipitates, and a small amount of Ti 4 Ni 2 O and Ni 3 Ti 2 phases. The Hf additions suppresses the formation of the Ti 4 Ni 2 O and Ni 3 Ti 2 phases and promotes the HfO 2 particles. When the Hf content is less than 5 at.%, the main precipitated phase is still Ni 4 Ti 3 , but which is gradually refined and spheroidized with the increase of Hf content. While the Ni 4 Ti 3 phases disappeared and the fine H-phases precipitated massively in the Ni 55 Ti 38 Hf 7 alloy. With the gaining content of Hf, the Vickers hardness increases, but the fracture toughness and tensile strength increase first and then decrease. When the addition of Hf is 3 at.%, the alloy possesses the best property with the fracture toughness of 21.02 MPa/m1/2 and the tensile strength of 2.25 GPa. • The Ni 55 Ti 45 alloy sonsists of NiTi phase, nanoscale Ni 4 Ti 3 precipitates, and slight Ti 4 Ni 2 O and Ni 3 Ti 2 phases. • The moderate Hf additions spheroidized and refined the Ni 4 Ti 3 precipitates and eliminate the Ti 4 Ni 2 O and Ni 3 Ti 2 phases. • The excessive Hf additions lead to the precipitation of H-phase. • With the gaining content of Hf, the mechanical properties improve first and then deteriorate. [ABSTRACT FROM AUTHOR]

Abstract In this study, double-layer Zn-Al-Mg coatings were manufactured by the PVD process and heat treatment. The microstructure and initial corrosion behavior were investigated during the 20-‍day immersion experiment. And the influence of heat treatment at different temperatures was discussed. The double-layer Zn-Al-Mg coating showed the superior initial corrosion resistance compared to the Zn55Al coating. And the best corrosion resistance can be achieved after 300 °C heat treatment (ZAM3). According to EIS and fitting results, the resistance value of ZAM3 corrosion products layer decreased first from 1.5 × 108 to 3.8 × 106 Ω·cm2 and then increased to 7.8 × 109 Ω·cm2 during 20-day immersion. And this resistance value of Zn55Al coating decreased gradually from 3.3 × 103 to 5.6 × 102 Ω·cm2. The double-layer Zn-Al-Mg coating can provide two types of protection in different stages, the barrier protection of surface passive film from the beginning to the 8th day and the formation of double layer corrosion products from the 8th day to the 20th day. After 20-day immersion, the corrosion products of Zn 5 (OH) 8 Cl 2 ·H 2 O and Zn 6 Al 2 (OH) 16 CO 3 ·4H 2 O are easier to form on the surface of ZAM. And on the outermost surface of ZAM3 corrosion products, it tends to be covered by zinc carbonate hydroxide. This is different from the fact that the outermost surface of ZA corrosion products is often covered by zinc hydroxide. Graphical abstract Unlabelled Image Highlights • The corrosion resistance of ZnAl coating is improved by PVD-Mg and heat treatment. • The product layer resistance of ZAM3 is up to 7.8 × 109 Ω·cm2 after 20d immersion. • Barriers of passive film and double layer products are found in two diverse periods. • Mg2+ ions promote the formation of compact corrosion products. [ABSTRACT FROM AUTHOR]