The effects of roughness and two-step process temperature on the growth of Al2O3 film on Fe-45Ni-25Cr-4Al based alumina forming austenitic (AFA) alloy under low oxygen pressure have been studied. Under oxidation process (850 degrees C/5 h) of low-temperature step of the two-step process, a continuous Al2O3 film forms on ground surface of AFA alloy, whereas a Cr2O3 film develops on polished AFA alloy surfaces. The mechanism of forming Al2O3 film on ground surface has been clarified. In addition, the high-temperature step of the two-step process critically promotes the growth of the protective Al2O3 film. When the oxidation temperature is excessively high (1100 degrees C), it causes wrinkled Al2O3 film morphology, leading to film cracking and spallation. Conversely, insufficient oxidation temperature (900 degrees C) leads to incomplete film coverage due to inadequate growth of the Al2O3 film. The optimal oxidation temperature of 1000 degrees C produces a continuous, dense, and well-adhered Al2O3 protective film. The influence of high temperature on oxide film growth morphology modification and internal stress has been analyzed.

The solidification microstructures of the Zn–5.4Al–0.6Ti-modified Zn–2.7Mg–2.5Al alloy and its mechanical properties, before and after modification, were analyzed. The results revealed that the Zn–5.4Al–0.6Ti alloy comprised η-Zn phase, binary Zn–Al eutectic, ternary T phase, and Al3Ti phase, and its melting temperature ranged from 383.8 to 391.5°C. As the Zn–5.4Al–0.6Ti content increased, the area fraction of the primary η-Zn phase in the Zn–2.7Mg–2.5Al alloy initially decreased and then increased. The tensile strength, impact toughness, and Vickers hardness of the alloy initially increased and then decreased with the increasing modifier content, while the elongation continuously decreased. At a modifier content of 7 wt

This study systematically evaluated the microstructure, melting behavior, tensile performance, wettability, interfacial reactions, and electrochemical corrosion resistance of low-temperature lead-free Sn-58Bi-xAg solder alloys. The results show that the alloys are primarily composed of Sn-rich phases, Bi-rich phases, and Ag3Sn intermetallic compounds. As the Ag content increases, Ag3Sn coarsens from finely dispersed particles into blocky structures, accompanied by evolution of the eutectic morphology. Differential scanning calorimetry indicates that the addition of 0.5

In order to further improve the degradation resistance and osteogenic property of the micro arc oxidation (MAO) coating of Mg alloys, the Mg alloy samples were oxidized in phosphate electrolyte, silicate electrolyte, first phosphate electrolyte + second silicate electrolyte, and first silicate electrolyte + second phosphate electrolyte. And the corrosion resistance, cytotoxicity, and osteogenic property of the samples were studied. The results showed that the Na2SiO3-MAO coated sample had more micropores than the CaP-MAO coated sample. The composite micro-arc oxidation (MAO) coatings obviously improved the degradation resistance of the alloy. Moreover, the samples fabricated first in silicate electrolyte and then in phosphate electrolyte showed the best corrosion resistance with the corrosion current density of only 0.1 µA/cm2, which was two orders of magnitude lower than the single silicate Na2SiO3-MAO coated (10.9 µA/cm2). Besides, the cytocompatibility of the MAO coated samples was good, presenting no cell toxicity. The extract from the Na2SiO3+CaP coated sample promoted cell proliferation, reaching almost 100

Barrier membrane plays a crucial role in periodontal assisted accelerated osteogenic orthodontics (PAOO), where they prevent soft tissue infiltration and provide a protected space for bone regeneration. Biodegradable Zn-Cu alloys have shown promising potential for such applications. In this preliminary study, the effects of Cu content on the degradation resistance, stress corrosion behavior, and cytocompatibility of as-rolled Zn-xCu alloys intended for PAOO barrier membranes were systematically investigated. The results revealed that with increasing Cu content, the corrosion resistance of the alloys decreased. Mechanically, the ultimate tensile strength (UTS) generally increased with Cu addition. Under stress corrosion conditions, the Zn-1Cu alloy demonstrated the highest fracture elongation (17

In this work, different heterogeneous structures were architected in the duplex Ni55.6Fe21.6Al8.9Cr8V5.9 (wt%) eutectic high-entropy alloys (EHEAs) via thermal mechanical processing. The obtained heterogeneous structures of the studied EHEAs mainly consist of deformed structure, substructure and recrystallized structure, achieving enhanced mechanical performance. As the annealing temperature increases, the strength of the cold-rolling EHEAs presents a gradual decreasing trend, while the fracture elongation shows an increasing trend. Specifically, the cold-rolling EHEA after annealing at 750℃ for 2 h exhibits an ultrahigh yield strength of ∼1615 MPa, an ultimate tensile strength of ∼1794 MPa and a fracture elongation of ∼8.2%. When the annealing temperature increases to 800 ℃, the yield strength and ultimate tensile strength of the cold-rolling EHEA decrease to ∼1311 MPa and ∼1530 MPa, and the fracture elongation increases to ∼15.4%. As the annealing temperature increases to 900 ℃, the yield strength and ultimate tensile strength of the cold-rolling EHEA further decrease to ∼895 MPa and ∼1285 MPa. The corresponding fracture elongation significantly increases to ∼22.4%. The difference in strength and ductility is mainly originated from different heterogeneous structure. When the annealing temperature rises, the volume fraction of deformed structure in the cold-rolling EHEAs decreases, while the recrystallized structure and substructure increase. The enhanced strength of the studied EHEAs mainly originates from the existence of high-volume deformed structure, and improved plasticity mainly originate from the increasing volume fraction of recrystallized structure.

Magnesium alloys, among the most promising biomaterials for orthopedic applications, face challenges with post-implantation infection. Copper offers potent antibacterial activity while exhibiting low biotoxicity at appropriate concentrations. This study investigated the incorporation of copper oxide nanoparticles into micro-arc oxidation (MAO) electrolytes to develop a coating combining enhanced antibacterial performance with improved corrosion resistance for Mg alloys. We systematically examined the influence of Cu content on the microstructure, corrosion resistance, antibacterial efficacy, cytotoxicity, and osteogenic properties of the coated Mg alloy samples. Electrochemical tests demonstrated that MAO coatings incorporating 1 g/L and 3 g/L CuO significantly enhanced corrosion resistance, and the corrosion rates were reduced to 0.16 mm/y and 0.38 mm/y, respectively. In immersion tests, the lowest corrosion rate of 0.31 mm/y was recorded for the 1 g/L CuO coating, which represents a 40

The effect of Hf on formation, residual stress, and adhesion of the pre-oxidation film on the surface of Fe–45Ni–25Cr–4Al–1Nb–0.3Si–0.45C–xHf (x = 0, 0.05, 0.25 wt.

Improving the corrosion resistance and osteogenic activity of Mg alloys is key to promoting their applications in clinical bone repair. In this study, a nano-CuO-containing micro-arc oxidation (MAO) coating was applied on the surface of a Mg-2Zn-1Gd-0.5Zr alloy and sealed with chitosan (CS) to construct a multifunctional CS/MAO composite coating. Material characterization and electrochemical corrosion tests showed that the CS coating formed a continuous layer on the MAO surface. The surface of the coating prepared with 1.5 g of CS was particularly dense and uniform, with micropores disappearing in some areas; in addition, it demonstrated excellent corrosion resistance, with a low corrosion rate of 0.136 mm/y. Biological studies revealed that the 1.5CS/MAO-coated Mg alloy promoted the proliferation and adhesion of MC3T3-E1 cells, enhanced the expression of alkaline phosphatase, and increased Ca nodule deposition. Moreover, animal experiments confirmed that the coated alloy significantly induced new bone formation and osseointegration in femoral defects with good biocompatibility and bone regeneration capacity. This study highlights the significant potential of 1.5CS/MAO composite-coated Mg alloys in bone regeneration therapy and provides a promising surface modification strategy for the development of advanced multifunctional coated Mg alloys.

This study systematically investigated the effects of rolling deformation on the microstructure, mechanical properties, and corrosion resistance of Zn–1Mg–1Cu alloy. Alloy samples were prepared through melting, heat treatment, and rolling with varying deformation levels (60, 70, 85

This work investigated the effect of yttrium addition on the pre-oxidation behavior of Fe-25Ni-20Cr-4Al-1Nb-1Mn-1.5Si-based alloys at 1000 degrees C in a 4% H-2 + 0.2% CH4 + Ar + 0.25% H2O atmosphere. The oxidation resistance and oxide scale adhesion were evaluated through cyclic oxidation tests and micro-scratch measurements. Results show that the Y-free alloy formed a discontinuous oxide layer, whereas all Y-containing alloys formed a continuous and dense Al2O3 scale. Incorporating 0.2 wt.% Y increased the work of adhesion by approximately 7 to 9 times relative to the Y-free sample, indicating a pronounced interfacial strengthening effect. The role of yttrium content and oxygen partial pressure in promoting alumina-scale formation was discussed based on thermodynamic considerations and microstructural evidence.

Biodegradable zinc alloys show promising potential for application in oral guided bone regeneration (GBR) due to their appropriate degradation rate and favorable osteogenic properties. However, their relatively low tensile strength and lack of antibacterial properties limit their broader clinical use. In this study, copper was introduced into the Zn-1Mg alloy to enhance both its mechanical, antibacterial, and osteogenic performance. The results indicate that the as-rolled Zn-1Mg-1Cu alloy exhibits the best overall mechanical properties, achieving a tensile strength of 276 MPa and an elongation of 6.2%. When the copper content exceeds 1%, the corrosion rate of the alloy increases significantly, while the antibacterial rate against E. coli reaches 100%. At copper contents below 1%, cytocompatibility improves with increasing copper content. However, further increase in copper content leads to a substantial rise in cytotoxicity. The results from the in vivo rabbit skull experiment showed that Zn-1Mg-1Cu alloy had good osteogenic performance with the BV/TV value of 55% after 8 weeks implantation, and many trabecular bones were observed from the bone slice. Therefore, the as-rolled Zn-1Mg-1Cu alloy demonstrates the greatest potential for use as an oral GBR membrane.

This study investigated the effect of Hf content on the self-healing behavior of Al2O3 films formed on alumina-forming austenitic (AFA) alloys under the decoking environment of petrochemical cracking process. AFA alloys with different addition of Hf (0–1 wt

The Cr2O3 film on the outer surface of traditional cracking furnace tubes is prone to spalling, which shortens the tube life. Fe-Ni-Cr-based austenitic stainless steel (AFA alloy) with added Al has attracted attention because it can form a more stable Al2O3 film on the surface. However, the alloy’s mechanical performance and the stability and oxidation resistance of the oxide film need to be improved simultaneously. This investigation examined silicon concentration variations (0–1.5 wt.%) on AFA alloy’s ambient-temperature tensile performance and oxidation response under reduced oxygen partial pressures (10−18–10−16 bar). The findings demonstrate that the alloy was composed of the FCC, B2-NiAl, and M23C6 phases. With Si addition, the B2-NiAl phase volume fraction increased. Mechanical testing demonstrated progressive elevation in tensile strength and hardness coupled with reduced elongation, attributable to combined solid-solution hardening and B2-NiAl precipitation strengthening. At low oxygen pressure, a continuous multi-layer oxide film developed on the alloy’s surface: the outermost layer was composed of a continuous Cr2O3 layer, with a fraction of MnCr2O4 spinel phase enriched on the outer surface. The middle layer was SiO2, which evolved from a particulate to a continuous layer with increasing Si content. The innermost layer was composed of Al2O3. Accelerated manganese diffusion through Cr2O3 facilitated MnCr2O4 spinel layer formation.

The effect of surface finishing on the oxidation of Fe-25Ni-20Cr-4Al-based alloy at 1000 degrees C in an Ar + 4 % H2 + (0.15 %-0.25 %) H2O atmosphere was studied. A multi-layered oxide film formed on the polished samples, while a single-layer Al-rich oxide developed on the ground samples. The low oxidation rate of the ground samples was controlled by Al2O3, while the oxidation rate of the polished samples was influenced by both the interstitial transport mechanism of Cr and the presence of a SiO2 layer. The synergistic effects of surface roughness and oxygen pressure on the early-stage oxidation behavior of alumina-forming austenitic alloys were further explored.

The combination of hydroxyapatite (HA) and Mg have excellent osteogenic performance. However, the corrosion resistance and adhesion of hydroxyapatite coating on Mg alloys fabricated by cold spraying are low. Consequently, treatment at 350, 400 and 450 °C for 5 h was adopted to solve these problems. Thereafter, microstructural characterization, electrochemical analysis, immersion test and cell cytotoxicity test were performed. The results showed that with increase in the heat treatment temperature, the HA coating became more compact even with lesser cracks. Moreover, the corrosion resistance of the HA-coated samples increased obviously after heat treatment. Meanwhile, after the 450 °C treatment, the corrosion current density was only 1.30 ± 0.42 μm, which meant that the corrosion resistance was improved by about 20 times compared with the untreated HA-coated sample. Moreover, the cell viability of the extract co-cultured with Murine calvarial preosteoblasts cells (MC3T3-E1) increased with the increase in the heat treatment temperature. The samples, after 450 °C treatment, exhibited the highest cell viability with the RGR value exceeding 98

In this research, we addressed the challenge of the rapid degradation of magnesium alloys, particularly AZ31B, which have great potential to be widely used in biomedical applications. To mitigate this issue, we developed a composite coating comprising polyvinyl alcohol (PVA), chitosan (CS), and titanium dioxide (TiO2) nanoparticles, in order to enhance the corrosion performance of the magnesium alloy. Our approach involved chemically synthesizing TiO2 particles (4-20 nm) and incorporating them into PVA and PVA/chitosan matrices at varying weight percentages, which affect the amino group. We employed x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) for comprehensive characterization, confirming the successful synthesis of TiO2 particles and the formation of composite coatings. The XRD analysis revealed the rutile phase of TiO2 particles with an average crystal size conducive to effective reinforcement, while SEM imaging showcased the spherical morphology of TiO2 particles. FTIR spectroscopy further elucidated the chemical bonding among TiO2, PVA, and chitosan, validating the composite’s structural integrity. Notably, atomic force microscopy (AFM) analysis demonstrated a significant reduction in surface roughness post-coating, indicating improved biocompatibility, a crucial factor in biomedical applications. Additionally, the hydrophobic nature of the PVA/TiO2-based coating and the hydrophilic character of the PVA/TiO2/CS-based composite coating were revealed through water contact angle measurements, offering versatile surface properties for different biomedical requirements. Furthermore, our investigation into the electrochemical behavior of the coated magnesium alloy in a 0.9

In the process of protecting ferrous materials, aluminum coating usually forms a dense oxide film on the surface of the iron-based alloy. However, the capacity of the sacrificial anode is rather insufficient. In order to solve this problem, the microstructure and electrochemical corrosion properties of Al-8Si-3Fe-xIn alloy under low chlorine conditions were studied. The results show that indium (In) dissolves to form In3+ and In+ reverse plating on the surface of the bare substrate to form a passivation film defect. When the In content is high, the segregated In forms an activation point in the form of a cathode phase. In activates tau 6 phase to form a micro-couple, which improves the non-uniform corrosion. The In-containing corrosion products at the phase boundary hinder the diffusion of Cl-. With an increase of In content, the self-corrosion potential (Ecorr) of the alloy shifts negatively, and the self-corrosion current density (Jcorr) decreases from 6.477 mu A/cm2 to 1.352 mu A/cm2, and then increases gradually. However, when the In content is 0.1%, the Ecorr of the alloy changes from -0.824 V to -0.932 V, and the Jcorr decreases from 6.477 mu A/cm2 to 4.699 mu A/cm2, suggesting that the use of sacrificial anode will give the best effect. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic) Al-8Si-3Fe-xIn (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic), In (sic)(sic)(sic)(sic) In3+(sic) In+ (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic) In (sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic) In (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). In (sic)(sic)(sic) tau 6(sic), (sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic) In (sic)(sic)(sic)(sic)(sic)(sic)(sic)Cl- (sic)(sic)(sic). (sic)(sic) In (sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(Ecorr)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(Jcorr) (sic) 6.477 mu A/cm2 (sic)(sic)(sic) 1.352 mu A/cm2, (sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic), (sic) In (sic)(sic)(sic) 0.1% (sic), (sic)(sic)(sic) Ecorr (sic)-0.824 V(sic)(sic)(sic)-0.932 V, Jcorr(sic)6.477 mu A/cm2(sic)(sic)(sic)4.699 mu A/cm2, (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

In this work, a comprehensive investigation was conducted on the impact of copper (Cu) addition on the microstructural features, mechanical characteristics, degradation performance, and biocompatibility of the as-rolled Zn-3Al-xCu alloy. It was observed that as the Cu content increased, the mechanical properties of the Zn alloys demonstrated significant improvement. Specifically, the ultimate tensile strength (UTS) and yield strength (YS) of the as-rolled Zn-3Al-1.5Cu alloy could achieve 300.56 +/- 1.66 MPa and 254.96 +/- 1.39 MPa, respectively, with an elongation of 24 +/- 0.45%. Nonetheless, an increase in Cu addition led to a reduction in the corrosion resistance of the Zn alloys. However, the rolled Zn-3Al-1.5Cu alloy displayed superior antibacterial properties, while Cu augmentation obviously boosted its cell viability. Furthermore, the cell proliferation rate of the rolled Zn-3Al-1Cu alloy steadily rose, peaking at 117.71% on the fifth day of co-culture.

Hot-dip aluminising technology is widely used in modern engineering, but Fe dissolution into the alloy during production degrades coating quality and performance. This study investigated the influence of Fe on the microstructure and corrosion resistance of Al-8Si coating alloys using SEM, TEM, EBSD and electrochemical methods. With increasing Fe content, specific phases precipitated sequentially: at 0.3 wt.% Fe, FCC Al, the Si phase, and the ternary eutectic Al9Fe2Si2 formed; at 1 wt.% Fe, the primary Al9Fe2Si2 phase emerged. As the Fe content increased, the corrosion current density first decreased but then increased. A lower Cl- concentration significantly elevated the electrode potential: in low Cl- solutions, a dense oxide film formed on alpha-Al, while Al9Fe2Si2 underwent preferentially oriented corrosion and fragmentation. This study reveals the coupling mechanism of Fe-rich phase evolution, micro-galvanic corrosion and passivation film stability, providing a theoretical basis for optimising hot-dipped Al alloys resistant to Cl- corrosion.