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In addressing issues related to defects in laser quenching technologies, this study undertakes surface passivation treatment on 2205 duplex stainless steel. The investigation explores the impact of different laser parameters on the corrosion resistance of the passive film on the steel surface. The findings may provide theoretical references for the laser passivation treatment and corrosion resistance mechanism of steel surfaces. [ABSTRACT FROM AUTHOR]

High-purity magnesia refractories were fabricated by brine magnesium hydroxide from the salt-lake brine (Qinghai Salt Lake) and Y 2 O 3 as an additive at 1780 °C. It avoided the substantial CO 2 emissions and ultra high temperature sintering process (＞1900 °C) when compared with the conventional magnesite-calcination technical approach. The results confirmed that Y 2 O 3 was dispersed on the MgO grains boundaries in the fabricated MgO aggregates, resulting in a decrease in apparent porosity and enhancing the grains' boundaries. With 3 wt% addition of Y 2 O 3 , the apparent porosity and bulk density of the sample reached to 15.9 % and 3.10 g/cm3 from 37.9 % to 2.30 g/cm3 of blank control group, respectively. Compared to the blank control without Y 2 O 3 -adding, the sample with 5 wt% Y 2 O 3 exhibited a 54.17 % increase in the resistance to molten slag. SEM results indicated that the incorporation of Y 2 O 3 in samples increased the porosity of small pores and enhanced grains boundaries, thereby suppressing slag's penetration. Furthermore, the Y 2 O 3 -adding was employed to disperse the MgO grains boundaries and existed as separate phases for grains boundaries enhancement. The slag attack of the fabricated MgO–Y 2 O 3 refractory raw materials were controlled by an inter-crystalline corrosion process. [ABSTRACT FROM AUTHOR]

Unique characteristics such as biocompatibility, degradation capability, and mechanical properties have positioned magnesium alloys as highly favorable choices for use in various medical devices and implants. However, their rapid degradation and associated challenges have limited their widespread use. This study conducts a thorough analysis into the corrosion behavior of magnesium alloys when open to various coatings, using both in vitro and in vivo environments. The review focuses on understanding the degradation mechanisms, factors influencing corrosion, and the resulting consequences. Additionally, it explores the composition of coatings and metals as effective means to control degradation, along with surface treatment and corrosion management methods. To enhance the degrading behavior, bioactivity, and biocompatibility of magnesium alloys, a multistep approach involving coating techniques such as HA coating, LDH, CaP, and titanium dioxide coating is recommended. These coatings have shown significant potential in improving the exterior properties of Mg alloys. Furthermore, using multifunctional coatings is extremely effective in creating secure and bioactive substrates for the application of biodegradable implants, demonstrating significant potential in the field of biomedical engineering. [ABSTRACT FROM AUTHOR]

The bio-corrosion behavior and bio-compatibility of TiNbZrTa and TiNbZrTaMo high entropy alloys (HEAs) are crucial for their efficient maintenance during biological implantation. In this work, TiNbZrTa and TiNbZrTaMo HEAs were successfully prepared via vacuum melting, with a β-type titanium alloy Ti35Nb7Zr5Ta, exhibiting good biocompatibility used as a comparison. Due to the high entropy effect of equal atomic ratios, both TiNbZrTa and TiNbZrTaMo HEAs exhibit body-centered cubic (BCC) structure and lattice distortion compared to the β titanium alloy Ti35Nb7Zr5Ta. Mo elements contribute to the formation of a new BCC phase, resulting in a white matrix rich in Ta and Mo, and a dark second phase rich in Ti, Zr, and Nb. Electrochemical test results at 37 °C shown that TiNbZrTa has a wider and more stable passivation area than TiNbZrTaMo. The XPS results shown that formation of the passive film is related to the main elements added. Ti, Nb, Ta and Mo formed oxides via the solid-liquid interface and migrate inward, while Zr is formed at the passivation film/metal substrate interface and migrates outward, finally forming the layered structure of the passivation film. Additionally, the cytotoxicity test of mouse fiber cells was carried out to evaluate the biocompatibility of the HEAs. The results shown that the cell proliferation rate of TiNbZrTa and TiNbZrTaMo HEAs reached 0 and 1, respectively, with TiNbZrTa exhibiting better biocompatibility, as adding Mo reduced the cell proliferation rate. These findings may provide a method for predicting the bio-corrosion behavior and bio-compatibility of HEAs used for biological implantation.

Effects of pre-treatment (either pre-deformation or composed of pre-aging and pre-deformation prior to aging) on the dislocation morphologies and subsequent precipitation, corrosion behaviors, and mechanical properties of a novel Al-8.26Zn-1.95Mg-1.89Cu-0.08Sc-0.17Zr (wt.%) alloy were investigated. Pre-existing Al3(Sc, Zr) dispersoids can pin dislocations induced by pre-deformation before aging to form dislocation cells and cell walls. As a result, bimodal microstructures are formed during the subsequent aging process, with coarse precipitates dispersed along dislocation walls and fine precipitates inside dislocation cells. Meanwhile, dislocations pinned by Al3(Sc, Zr) dispersoids nearby grain boundaries inhibit the diffusion of solutes towards grain boundaries, which can modify grain boundary features by decreasing the potential difference between grain boundaries and grain interiors, and reducing precipitation-free zone width and grain boundary precipitate size. In particular, pre-aging prior to pre-deformation makes the dislocation distribution more uniform, which increases the volume fraction of nanoprecipitates without significant coarsening and further improves the grain boundary characteristics. Compared with the traditional T74 treated sample, these multiple microstructures significantly enhance the corrosion resistance of the alloy with less strength degradation. This study offers novel insights into the strengthening and corrosion mechanisms of pre-treated Al–Zn–Mg–Cu alloys with Zr and Sc microalloying.

In this study, to reactivate the oxide film and to secure biocompatibility, plasma electrolytic oxidation (PEO) treatment and hydroxyapatite (HA) deposition via mechanical coating (MC) processes were investigated. This experimental approach involved subjecting the Ti–6Al–4V alloy specimens to PEO treatment, followed by MC with HA powder for different hours as HA has the potential to increase bioactivity and surface characteristics due to its chemical composition and structural properties similar to natural bone. Therefore, the study aimed to examine the effects of MC with HA powder for 0, 1, 3, 5, 7, and 9 h on PEO-coated Ti–6Al–4V alloy discs for analyzing the surface characterization, phase analysis, surface roughness, wettability, adhesion strength, hardness, corrosion behavior, and cell proliferation properties for dental implant use. The findings demonstrate that prolonged HA milling enhances the substrate's mechanical strength, corrosion resistance, and adhesion properties. The presence of prominent anatase and HA peaks, particularly in the 5 MC-PEO, 7MC-PEO, and 9 MC-PEO samples, validates the synergistic impact of the PEO oxide layer and HA milling, resulting in outstanding corrosion resistance and biocompatibility. Cell culture analysis reveals a positive correlation between increased milling time and enhanced cell proliferation, particularly towards small-sized HA particles. [Display omitted] [ABSTRACT FROM AUTHOR]

Biodegradable suture anchors based on Mg-Nd-Zn-Zr alloy were developed for ligament-to-bone fixation in rotator cuff surgeries. The Mg alloy anchors were designed with structural features of narrow tooth and wide tooth, and simulated through finite element analysis (FEA). Meanwhile, the corrosion behaviors of the Mg alloy anchors were studied by immersion test and the mechanical properties were investigated by measuring the maximum torque and pull-out force. The simulation result showed that the wide-tooth anchor exhibited more a uniform stress distribution and lower shear stress in the torsion process, suggesting a satisfactory torsional resistance of this structure. Meanwhile, the wide-tooth anchor exhibited a lower Von-Mises stress after applying the same pull-out force in the simulation, indicating a higher resistance to pull-out failure of the anchor. The result of the immersion test indicated that the wide-tooth anchor exhibited a slightly slower corrosion rate in Hank's solution after 14-day immersion, which was beneficial to enhance the structural and mechanical stability of the biodegradable suture anchor. Furthermore, the results of the mechanical properties test demonstrated that the wide-tooth anchor showed superior performance with higher maximum torques and axial pull-out forces before and after corrosion. More importantly, the axial pull-out force and maximum torque for the wide-tooth anchor decreased by 5.86% and 8.64% after corrosion, which were significantly less than those for the narrow-tooth anchor. Therefore, the wide-tooth suture anchor with lower corrosion rate, higher mechanical properties and structural stability is a promising candidate for ligament-bone fixation in the repair of rotator cuff injuries. [ABSTRACT FROM AUTHOR]

In this work, Fe-20Cr-20Mn-0.75N (wt.%) high-nitrogen stainless steel (HNSS) was studied using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and electrochemical testing. The corrosion behaviors of Fe-20Cr-20Mn-0.75N HNSS with different concentrations of NaCl were studied. The composition of a passive film on Fe-20Cr-20Mn-0.75N HNSS was analyzed using X-ray photoelectron spectroscopy (XPS) at an applied potential of 0.2VSCE. The results showed that, with the increase in Cl− concentration, the corrosion tendency and corrosion rate of Fe-20Cr-20Mn-0.75N HNSS get higher. In the solution of a low Cl− concentration, the fraction of Fe and Cr oxides in the passive film is higher, and the passive film is thicker and more stable. By increasing the stability of the passive film and preventing its rupture, the elevated NH4+ concentration can enhance the corrosion resistance of Fe-20Cr-20Mn-0.75N HNSS in a NaCl solution. [ABSTRACT FROM AUTHOR]

This review provides an overview of Cu–Ni–Sn alloys, which have great advantages as a potential substitute for beryllium bronze. The characteristics of spinodal decomposition in Cu–Ni–Sn alloys are thoroughly discussed by conducting a comprehensive analysis of thermodynamics and the phase diagram. The traditional casting process for Cu–Ni–Sn alloys is subject to several limitations, including segregation during solidification as a primary constraint. Another significant limitation is the occurrence of discontinuous precipitation during aging. Thus, the strategies to overcome these limitations are further elaborated. Commonly used methods include thermal-mechanical processing and composition design. Finally, the application of Cu–Ni–Sn alloys in friction and corrosion is discussed. The purpose of this review is to provide a comprehensive summary of the research progress and significant limitations encountered in Cu–Ni–Sn spinodal alloys. This includes a discussion of traditional casting methods as well as novel preparation techniques. The aim is to serve as a valuable reference for the development of new manufacturing methods and the future advancement of Cu–Ni–Sn spinodal alloys.

• A holistic overview on the corrosion behaviors of nZVI in water is given. • Various environmental factors affecting nZVI corrosion are summarized. • The methods to establish the corrosion kinetic models of nZVI are categorized. • The critical knowledge gaps and future research needs of nZVI are proposed. Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron (nZVI) in aquatic environment is particularly significant for understanding the reactivity, longevity and stability of nZVI, as well as providing theoretical guidance for developing a cost-effective nZVI-based technology and designing large-scale applications. Herein, this review gives a holistic overview on the corrosion behaviors and kinetics of nZVI in water. Firstly, Eh-pH diagram is introduced to predict the thermodynamics trend of iron corrosion. The morphological, structural, and compositional evolution of (modified-) nZVI under different environmental conditions, assisted with microscopic and spectroscopic evidence, is then summarized. Afterwards, common analytical methods and characterization technologies are categorized to establish time-resolved corrosion kinetics of nZVI in water. Specifically, stable models for calculating the corrosion rate constant of nZVI as well as electrochemical methods for monitoring the redox reaction are discussed, emphasizing their capabilities in studying the dynamic iron corrosion processes. Finally, in the future, more efforts are encouraged to study the corrosion behaviors of nZVI in long-term practical application and further build nanoparticles with precisely tailored properties. We expect that our work can deepen the understanding of the nZVI chemistry in aquatic environment. [Display omitted] [ABSTRACT FROM AUTHOR]

Aluminum‐based glassy alloys and composites exhibit more than two times higher tensile and compressive strength and superior corrosion resistance compared to the conventional Al alloys. However, the low glass‐forming ability (GFA) of Al‐based glass‐forming compositions restricts the synthesis of large dimension Al‐based amorphous alloys. In contrast, powder metallurgy route leads to synthesis of higher‐dimension Al‐based metallic glasses and composites. A detailed review on the efforts made to improve the dimension and mechanical properties of the Al‐based glassy alloys and composites is essential to further develop these materials for industrial applications. Researchers aspiring to develop high‐strength light‐weight materials can be benefited from such a detailed review on Al‐based amorphous alloys and composites. In this review article, a holistic approach is made to understand the GFA, crystallization behavior, corrosion resistance, and mechanical and electronic properties of Al‐based glassy alloys and composites. The effects of various alloying elements on GFA and criteria to optimize Al‐based glass‐forming alloy composition are discussed. The crystallization behavior is discussed with phase‐separation and quenched‐in nuclei models. The effects of various crystalline phases in the amorphous matrix on corrosion resistance and mechanical and electronic properties are discussed in detail. [ABSTRACT FROM AUTHOR]

A novel low-alloyed Mg–1Bi–1Zn–1Ag alloy system was developed by extrusion at different extrusion ratios to achieve a bimodal grain structure. The dependence of the corrosion behavior and tensile properties on the grain structure was analyzed. The sample obtained at the extrusion ratio of 9 (BZQ111-R9) displayed a bimodal grain microstructure. In addition, its dominant corrosion mode was filiform with intergranular corrosion at a low corrosion rate of 0.06 mm/a. An improved synergy between strength (tensile yield strength of 207.1 MPa) and ductility (elongation of 35.9%) was realized in the BZQ111-R9 sample. Thus, the proposed approach can develop low-alloyed Mg–Bi-based alloys with excellent synergy between the corrosion resistance and tensile properties based on the control of the bimodal grain structure.

The Mg–Er–Ni alloy with comparable strength and solubility was prepared by controlling the Ni content. The mechanical properties and corrosion mechanism of alloys with long-period stacking ordered (LPSO) phase, as well as those with both LPSO and γʹ phases, were investigated and clarified. This study focused on investigating the underlying reasons for the high mechanical strength and fast corrosion rate of the Mg–13Er–3Ni alloy with LPSO and γʹ phases. The highest corrosion rate of the Mg–13Er–3Ni (wt.%) alloy is not only associated with the high volume fraction of the LPSO phase, which provides a larger zone for the corrosion cathode rather than forming a corrosion barrier, but also linked to the introduction of the γʹ phase that forms new sites for galvanic corrosion and avoids the formation the Er2O3 corrosion product film with corrosion-resistant. Moreover, The high mechanical properties of Mg–13Er–3Ni alloy are mainly attributed to the texture strengthening, dislocation strengthening and the second phase reinforcement that were caused by high volume fraction of LPSO phase and the precipitation of lamellar γʹ phase in Mg matrix. Generally, Compared to the Mg–13Er-1.5Ni (wt.%) alloy, the corrosion rates and mechanical strength of Mg–13Er–3Ni (wt.%) alloy were increased significantly by 302.8% and 50.3%, respectively, by coupling the LPSO and γʹ phases. Its ultimate tensile strength of 445 MPa and corrosion rare of 128.5 mg cm−2 h−1, which provides a new high strength and rapid corrosion Mg alloy materials for fracturing tools application.

Refill friction stir spot welding (RFSSW) of high strength aluminum alloy has a wide application prospect. However, there are few studies between the microstructure and macroscopic corrosion behavior, causing a significant impediment in corrosion protection of the joint. Therefore, the microstructure and corrosion behavior of 7050 aluminum alloy RFSSW joint was investigated in this paper. Due to the difference of microstructure, the joint can be divided into five zones, namely stir zone (SZ), thermo-mechanically affected zone (TMAZ), heat affected zone-I (HAZ-I), heat affected zone-II (HAZ-II) and base metal (BM). Therein, the grain size and the micron-sized second phase particles of SZ were fine, while other areas were coarse. And they were mainly Al2CuMg and Al7Cu2Fe. After intergranular corrosion and exfoliation corrosion tests, it was indicated that the grain morphology and second phase particles did not significantly affect the corrosion susceptibility, but the continuous degree of intergranular nano-precipitates was the key factor. A coefficient r was defined to quantitatively characterize the continuous degree of intergranular nano-precipitates. The HAZ-II and TMAZ exhibited high corrosion sensitivity with a high value of r, while HAZ-I and SZ exhibited low corrosion sensitivity with a low r. The corrosion mechanism was also briefly discussed.

The demand for soluble magnesium alloys with high plasticity used for sealing tools in petroleum field is increasing. Here, the effects of Ni content (0.1, 0.2 and 0.5wt.%) on microstructure, mechanical properties and corrosion rate of Mg-2Gd alloy were studied. The volume fraction of LPSO phases and the average grain size (α-Mg) increased and decreased with the increase of Ni content, respectively. After adding Ni, the texture changed from the rare earth texture to the basal fiber texture, and the strength, hardness and corrosion rate were increased with an acceptable decrease in elongation: the ultimate tensile strength/elongation/corrosion rate of the Mg-2Gd alloy and Mg-2Gd-0.5Ni alloy were 191 MPa/23.1%/15.2 mm·y-1, 287 MPa/18.1%/499.9 mm·y-1, respectively. Therefore, the addition of Ni effectively improved the strength and degradation rate of the Mg-2Gd alloy, which was mainly due to the grain refinement, the enhancement of basal fiber texture and the appearance of LPSO phases.

Laser cladding is commonly used to improve the wear and corrosion resistance of the substrate material. However, mechanical machining is necessary, because the surface irregularities and poor surface roughness after laser cladding. It is urgent to investigate the effect of machining on the corrosion resistance of the laser cladded layers, so as to avoid the reduction of corrosion resistance due to the use of inappropriate cutting parameters. In the present study, the influence of turning-induced surface roughness on the corrosion resistance from the viewpoint of corrosion potential was analyzed first. The corrosion potential is the result of the effect of roughness height parameters and functional parameters. Second, the effect of the machining and subsequent burnishing on the corrosion resistance was analyzed by comparing the corrosion behaviors of the turned and burnished surfaces. The polarization resistance is critically increased by subsequent burnishing. Third, the sensitivity of the machined surface on corrosion resistance was analyzed by EIS method. The strengthening mechanism of machining and subsequent burnishing on the corrosion resistance was determined. On the basis of this research, it is expected to be used to guide the selection of appropriate feed parameter in prior turning to improve the strengthening effect of subsequent burnishing, and then, to improve the surface integrity and corrosion resistance of the laser cladded layer. [ABSTRACT FROM AUTHOR]

Biodegradable suture anchors based on Mg-Nd-Zn-Zr alloy were developed for ligament-to-bone fixation in rotator cuff surgeries. The Mg alloy anchors were designed with structural features of narrow tooth and wide tooth, and simulated through finite element analysis (FEA). Meanwhile, the corrosion behaviors of the Mg alloy anchors were studied by immersion test and the mechanical properties were investigated by measuring the maximum torque and pull-out force. The simulation result showed that the wide-tooth anchor exhibited more a uniform stress distribution and lower shear stress in the torsion process, suggesting a satisfactory torsional resistance of this structure. Meanwhile, the wide-tooth anchor exhibited a lower Von-Mises stress after applying the same pull-out force in the simulation, indicating a higher resistance to pull-out failure of the anchor. The result of the immersion test indicated that the wide-tooth anchor exhibited a slightly slower corrosion rate in Hank’s solution after 14-day immersion, which was beneficial to enhance the structural and mechanical stability of the biodegradable suture anchor. Furthermore, the results of the mechanical properties test demonstrated that the wide-tooth anchor showed superior performance with higher maximum torques and axial pull-out forces before and after corrosion. More importantly, the axial pull-out force and maximum torque for the wide-tooth anchor decreased by 5.86% and 8.64% after corrosion, which were significantly less than those for the narrow-tooth anchor. Therefore, the wide-tooth suture anchor with lower corrosion rate, higher mechanical properties and structural stability is a promising candidate for ligament-bone fixation in the repair of rotator cuff injuries.

The Selective Laser Melting (SLM) is an effective method to produce highly corrosion resistant Oral Alveolar Implants (OAI) by changing the scanning speed. Nevertheless, the long-term corrosion behavior of SLM 316L orthodontic bracket alloys in artificial saliva is overlooked in previous studies. In this study, 316L SS samples fabricated by SLM at different scanning speeds (800 mm/s, 1200 mm/s, and 1600 mm/s) were conducted a long-term (90 days) immersion test by being put into artificial saliva with three different pH values (pH 1.5, pH 4, and pH 6). The morphology, XRD and especially corrosion behavior of the samples fabricated by SLM and forging were investigated. The XRD results exhibit that high-speed scanning accelerates the cooling rate and inhibits the δ → γ phase transformation proceeding. Corrosion results show that the corrosion attack induced by pre-existing pores will expand through the crevices and break down the surface structure around the pores, leading to corrosion damage area to expand to several times of the original pore area. Besides, the mean corrosion rate of the sample at a scanning speed of 800 mm/s shows better corrosion resistance in artificial saliva of pH 4 and pH 6. Compared with wrought 316L SS samples, the SLM 316L SS samples had an obvious difference in the performance of corrosion rate and corrosion behaviors.

Fracturing tools for oil and gas exploitation require high mechanical properties and degradability. Zn alloys are possible to have good mechanical properties and much lower cost than widely used rare-earth Mg alloys, so it is worthy to develop Zn alloys as alternative materials. In this paper, a novel shell-like microstructure of Zn-5Mn alloy has been realized by bottom circulating water cooling. MnZn 9 phase appears by the first time in Zn-Mn alloys with Mn < 6.4 wt%. This phase leads to the formation of hard MnZn 9 /MnZn 13 core/shell structure with a high volume fraction of 76 %, dispersed uniformly in soft Zn phase. The alloy has excellent compressive properties without fracture even when stress and strain reach 2776 MPa and 80 %, respectively. Its ultimate uniform compressive stress and strain are 865 MPa and 56 % respectively, beyond widely used dissoluble Mg alloys. Weight loss rate of the Zn-5Mn alloy is two times that of pure Zn, immersed in 3 wt% KCl solution at 93°C. The shell-like Zn-5Mn alloy provides guiding significance of applying Zn alloys in fracturing tools for oil and gas exploitation. [Display omitted] • MnZn 9 phase appears by the first time in Zn-Mn alloys with Mn < 6.4 wt%. • A novel MnZn 9 /MnZn 13 core/shell structure is dispersed uniformly in Zn phase. • Zn-5Mn alloy has the best compressive mechanical properties in degradable materials. • Weight loss rate of the alloy in 3 wt% KCl at 93°C is twice that of pure Zn. [ABSTRACT FROM AUTHOR]

The microstructure, corrosion behavior, and electrochemical behavior of as-cast Mg-4Y-xZn (x=1,2,3,4 wt.%) are studied by SEM, weight loss and electrochemical tests. Mg12YZn (X), Mg3Y2Zn3 (W) and Mg24Y5 constitute the phase composition system of the alloy. When Zn content is 1 wt.%, all tests reveal that alloy has the optimal corrosion performance. The second phase in these alloys, due to their nobler nature than α-Mg, exists as a cathode during the corrosion process, so that α-Mg preferentially occurs corrosion to accelerate the formation of corrosion pits. After soaking in 3.5 wt.% NaCl solution for some time, the stability of the W phase changed, and gradually dissolved, which was finally removed by chromic acid used for removal of corrosion products. In addition, X phase can be used as an anode in the micro-galvanic cells formed with W phase to reduce the corrosion rate of α-Mg and thus improve the corrosion performance of the alloy.

A series of Mg–Ti composites are fabricated by high-pressure solid-state sintering (HPSSS) technique developed in our lab. The correlation between microstructures and corrosion behaviors is comparatively studied. It is shown that the Mg/Ti interface primarily determines the corrosion resistance of the composites, and the corrosion process is a comprehensive action of material composition, interface content, corrosion potential and interfacial oxide. Besides, the present semi-degradable Mg–Ti composites retain superior structure stability after Mg degradation due to the strong interfacial bonding obtained by the high-pressure solid-state sintering. All of the derived porous Ti exhibits a superior compressive plasticity, and the mechanical properties of the porous Ti can be readily adjusted by tuning the porosity. With superior mechanical properties, low Young's modulus and favourable pore size, the present porous Ti offers superior mechanical compatibility, demonstrating promising prospect in the load bearing biomedical applications.

Magnesium alloys, a novel functional material for the fabrication of fracturing tools, are being paid more and more attentions recently due to their relatively high mechanical properties and fast dissolubility ability after fracturing. In this study, the novel extruded Mg–10Gd–3Y–0.3Zr–xNi alloys will be reported and their microstructure, mechanical and corrosion behaviors will be also studied. The results show that Ni contents influence phase precipitation behaviors. With adding 0.2 wt% Ni, a large amount of Zr7Ni10 phases will be precipitated insides α-Mg matrix, directly leading to degradation of strength and large corrosion rate. With further increasing Ni contents, the precipitation phases can be changed from Mg5RE to 18R-LPSO structure, resulting in higher mechanical properties and faster corrosion rate. Moreover, adding Ni element also change the texture orientation by influencing the precipitation behavior of the alloys. The alloys invented in this paper have attained the highest compressive and tensile properties among all the reported dissoluble magnesium alloys. This work is beneficial in understanding the role of Ni in the magnesium alloys and provides more materials alternatives for the fabrication of dissoluble fracturing tools.

AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA) has attracted significant interest among researchers due to unprecedented mechanical properties compared with single-phase solid solution high entropy alloys; however, the high content of cobalt element limits its engineering applications. In this paper, the mechanical and corrosion behaviors of cost-effective AlCrFeNi3.1 and AlCrFe2Ni2.1 HEAs were systematically studied by tensile tests and electrochemical methods; meanwhile, the results were compared with AlCoCrFeNi2.1 EHEA. The results indicated that all the studied HEAs showed dual phase microstructure composed of FCC and BCC/B2 phases. Due to the hetero-deformation induced strengthening, all the studied HEAs showed an excellent combination of strength and ductility with fracture strength over 1 GPa and fracture strain exceeding 17%, indicating that substituting the cobalt element of AlCoCrFeNi2.1 EHEA by nickel or iron element is feasible from the perspective of mechanical properties. As for the corrosion behaviors in 3.5 wt.% NaCl solution, AlCrFeNi3.1 HEA exhibited the best corrosion resistance due to the high volume fraction of the corrosion resistant FCC phases and low Al/Cr ratio of BCC/B2 phases, while AlCrFe2Ni2.1 HEA showed the worst corrosion resistance owing to the high Al/Cr ratio of BCC/B2 phases. [ABSTRACT FROM AUTHOR]

Herein, fiber laser welding experiments are performed to evaluate the microstructure, mechanical properties, and corrosion behavior of dissimilar/similar joints between DP980 and QP980 steel. Results show that the fusion zone (FZ) of all joints consists of lath martensite with high microhardness (≈480 HV); the retained austenite content in the subcritical heat‐affected zone (HAZ) in the QP980 side of the dissimilar weld joint (WJ) is less than base metals (BMs). Lower hardness in the subcritical HAZ is found compared with BMs in all joints. The microstructure of softening zones is tempered martensite, and the reduction in hardness is about 8.5−10.8% of BMs, which has a great influence on the tensile fracture position of WJs. All joints fracture at softening zones with a typical feature of ductile fracture, and the joint efficiencies are above 96%. The electrochemical corrosion test reveals that the welded samples exhibit a higher corrosion rate compared with the BMs due to the increase in martensite content and area fraction of grain boundary. [ABSTRACT FROM AUTHOR]

In this paper, Mo-based titanium–zirconium (TZM) alloys containing 0.06, 0.07, 0.08 and 0.09% Zr were produced by mechanical alloying method and the effect of Zr on the microstructure and corrosion behavior of the TZM alloy was studied. Microstructural properties of TZM alloys were characterized by SEM + EDS, XRD analysis and micro hardness tests. In corrosion tests, Tafel extrapolation and Electrochemical Impedance Spectroscopy (EIS) methods were used in solutions with different pH values (pH 4, pH 7 and pH 10). As a result of the studies, it is seen that depending on the amount of Zr added to the TZM alloy, different secondary phases are formed in the microstructure of Mo matrix and the grain boundaries. According to Tafel curves in pH 4, 7 and 10 solutions of TZM alloys with different Zr composition and electrochemical impedance spectroscopy (EIS) results. The highest corrosion resistance (in mm/year) was obtained in 0.09% Zr TZM alloy, the lowest corrosion resistance was obtained in 0.06% Zr TZM alloy. Moreover, the highest corrosion resistance was obtained at pH 7 and the lowest corrosion resistance at pH 10. [ABSTRACT FROM AUTHOR]

Dissoluble magnesium alloys for fabrication of fracturing tools have received increasing attention in recent years. However, most of the existing research is focused on the small-sized samples prepared in the laboratory, and there is almost no report on the industrial dissoluble magnesium alloys. In this study, large-scale Mg-Al-Zn-Mn-Ca-Ni alloys with a diameter of 110 mm were prepared by a semi-continuous casting and two-step extrusion method, and the corresponding microstructure and mechanical and corrosion properties were also investigated. It was found that after two-step extrusion, the mainly precipitate phases in the Mg-Al-Zn-Mn-Ca-Ni alloy are bulk-like AlMnNi, strip-like Al3Ni, and granular-like and lamellar-like Mg17Al12 phases. Due to the combined effects of grain refinement and precipitation strengthening, the Mg-Al-Zn-Mn-Ca-Ni alloy obtained excellent mechanical properties after two-step extrusion, and its ultimate tensile strength, yield strength, and elongation were 314.6 MPa, 191.2 MPa, and 13.1%, respectively. Moreover, the corrosion rate of the alloy in 3 wt.% KCl at 93 °C was as high as 97.61 mg·cm−2·h−1. This work provides a high-performance, low-cost, and large-scale alloy product for the fabrication of dissoluble fracturing tools. [ABSTRACT FROM AUTHOR]

Making a tantalum carbide (TaC) coating on Ta substrates is an effective way to improve the mechanical and anti-corrosion properties of Ta. However, conventional methods for making a TaC coating require high-temperature conditions of over 1600 °C to get a TaC thickness of > 20 μm. Herein, a TaC coating of > 20 μm thickness was prepared on a Ta substrate in molten CaCl2-CaC2 at 850 °C for 4 h. In the molten salt electrolyzer, the Ta plate served as the anode where C22− was oxidized and simultaneously reacted with Ta to form a TaC layer, and Ca2+ was reduced and alloyed with C to form CaC2 that can replenish the C22−. The electrolytic TaC exhibited an average hardness of 962 HV that was 6 times of the bare Ta substrate. In the 3.5 wt% NaCl solution, the TaC coating displayed a higher corrosion potential and lower corrosion current density (0.48 V, 1.59 μA cm−2) than Ta substrate (0.35 V, 1.85 μA cm−2) and the mixtures of TaC and Ta2C (0.35 V, 1.78 μA cm−2), indicating its better corrosion resistance. The molten salt anodic carbidation may lead to a general way to prepare transition metal carbide coatings with enhanced carburizing kinetics at < 1000 °C. [ABSTRACT FROM AUTHOR]

Making a tantalum carbide (TaC) coating on Ta substrates is an effective way to improve the mechanical and anti-corrosion properties of Ta. However, conventional methods for making a TaC coating require high-temperature conditions of over 1600 °C to get a TaC thickness of > 20 μm. Herein, a TaC coating of > 20 μm thickness was prepared on a Ta substrate in molten CaCl2-CaC2 at 850 °C for 4 h. In the molten salt electrolyzer, the Ta plate served as the anode where C22− was oxidized and simultaneously reacted with Ta to form a TaC layer, and Ca2+ was reduced and alloyed with C to form CaC2 that can replenish the C22−. The electrolytic TaC exhibited an average hardness of 962 HV that was 6 times of the bare Ta substrate. In the 3.5 wt% NaCl solution, the TaC coating displayed a higher corrosion potential and lower corrosion current density (0.48 V, 1.59 μA cm−2) than Ta substrate (0.35 V, 1.85 μA cm−2) and the mixtures of TaC and Ta2C (0.35 V, 1.78 μA cm−2), indicating its better corrosion resistance. The molten salt anodic carbidation may lead to a general way to prepare transition metal carbide coatings with enhanced carburizing kinetics at < 1000 °C. [ABSTRACT FROM AUTHOR]

The influence of various Ag contents on the microstructure, mechanical properties, and corrosion behavior of extruded Al-4.0Cu-1.1Li-0.4Mg-xAg-0.2Mn-0.2Zr (x = 0.4 and 0.9, wt.%) alloys was investigated. The alloy with 0.9 Ag content contains higher number density of slender T1 (Al2CuLi) precipitates along with some θ' (Al2Cu) phases in the matrix than the alloy with 0.4 Ag content, which is associated with a more rapid hardening response and higher mechanical properties and corrosion resistance, particularly for aging at 130 °C. When aging at high temperatures (above 160 °C), the increase of Ag content mitigates hardness loss by preventing the T1 precipitates from coarsening, and makes the alloy decorate more coarse precipitates at grain boundaries, which leads to the fracture morphology mainly occupied by intergranular fracture. Furthermore, due to the simultaneous promotion of T1 precipitates at grain boundaries and in grain interiors, the 0.9 Ag-containing Al-Cu-Li-Mg-Ag alloy has almost no improvement in corrosion resistance. [ABSTRACT FROM AUTHOR]

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For the development of biological ZrTi alloys with excellent properties, microstructure evolution, mechanical properties and corrosion behaviors of a novel Zr–40Ti–4.5Al–4.5 V (Z40T, wt.%) alloy resulted from different cooling rates have been investigated. Variations in the phase composition and microstructure are observed with X-ray diffraction, metallography, scanning and transmission electron microscopy analyses. The results demonstrate that α'' martensite can be formed through a nondiffusive phase transformation of the β phase during rapid cooling. However, slow cooling rates provide a stable α phase due to atomic diffusion and rearrangement. Furthermore, the grain size of each phase also changes as a result of different cooling rates. Moreover, the mechanical properties and corrosion behaviors are determined with uniaxial tensile testing and potentiodynamic polarization testing in NaCl solution. The mechanical properties and corrosion behaviors of the Z40T alloy are closely related to the phase composition and microstructure. The sample strength and fracture elongation changes obviously as the cooling rates change from water cooling to slow cooling. Analysis of potentiodynamic potential curves indicates that corrosion potential increases and corrosion current density decreases as the cooling rate is increased from slow cooling to water cooling. The variation in the mechanical properties and corrosion behaviors of the Z40T alloy are ascribed to the differences in the crystal structure and grain size of the constituent phase.

Because the CMAS corrosion and phase transformation at elevated temperatures above 1250 °C have limited the applications of traditional YSZ, the design of novel thermal barrier materials is a hotspot. GdTaO 4 is considered as a type of potential novel thermal barrier material owing to its low thermal conductivity. In this study, the mechanical and thermal properties, CMAS corrosion resistance, and the wettability of the GdTaO 4 were studied and compared with that of YSZ. The results show that the coefficient of thermal expansion and hardness of GdTaO 4 are 14.1 × 10−6 K−1 (1350 °C) and 534.2 Hv 0.3 respectively. The thickness of CMAS reaction layer of GdTaO 4 is ~30.8 μm after 24 h reaction at 1350 °C, which is thinner than that of YSZ. After corrosion reaction, the CMAS glass aggregated instead of completely disappearing or continuously extending over the surface of GdTaO 4. The main reaction product is Ca 2 Ta 2 O 7 , and the anorthite phase may not be detected, which is similar to YTaO 4. By comparison, the dense substrate of YSZ became porous and CMAS glass has disappeared after 10 h. CMAS corrosion at 1350 °C. The on-line contact angle results show that the wettability of CMAS on GdTaO 4 is worse than that on YSZ at 1350 °C, while the opposite of the work of adhesion, which indicates that GdTaO 4 can remove liquid CMAS more easily than YSZ TBCs during the service. Furthermore, the corrosion depth and areas of GdTaO 4 are smaller than those of YSZ in the same situation. These findings suggest that GdTaO 4 possesses better high-temperature properties and CMAS corrosion resistance than YSZ as a kind of potential of thermal barrier material. [ABSTRACT FROM AUTHOR]

Magnesium alloys, a novel functional material for the fabrication of fracturing tools, are being paid more and more attentions recently due to their relatively high mechanical properties and fast dissolubility ability after fracturing. In this study, the novel extruded Mg–10Gd–3Y–0.3Zr–xNi alloys will be reported and their microstructure, mechanical and corrosion behaviors will be also studied. The results show that Ni contents influence phase precipitation behaviors. With adding 0.2 wt% Ni, a large amount of Zr 7 Ni 10 phases will be precipitated insides α-Mg matrix, directly leading to degradation of strength and large corrosion rate. With further increasing Ni contents, the precipitation phases can be changed from Mg 5 RE to 18R-LPSO structure, resulting in higher mechanical properties and faster corrosion rate. Moreover, adding Ni element also change the texture orientation by influencing the precipitation behavior of the alloys. The alloys invented in this paper have attained the highest compressive and tensile properties among all the reported dissoluble magnesium alloys. This work is beneficial in understanding the role of Ni in the magnesium alloys and provides more materials alternatives for the fabrication of dissoluble fracturing tools. [ABSTRACT FROM AUTHOR]

A systematic investigation was undertaken to explore the influence of microstructure evolution in the as-cast, heat-treated, and as-extruded on the corrosion properties of a high-performance Mg-5.6Dy-3.1Ni alloy, which includes two intermediate phases. It was found that degradation rate of both as-cast and heat treated alloys primarily depended on the distribution of the LPSO and Mg 6 Ni intermetallic phases. For the as-extruded alloy, the degradation rate depended on both the distribution of the LPSO and Mg 6 Ni phases and the grain refinement of the matrix. Compared with as-cast alloy, the corrosion barrier was formed and inhibited the corrosion propagation after heat treatment. This was attributed to the network distribution of the LPSO phase, coupled with a uniform distribution of Mg 6 Ni phase. After extrusion, After extrusion, the streamlined distribution of the stripped LPSO phase. This led to a reduced corrosion barrier in the extrusion direction (ED) sample, resulting in a higher degradation rate compared to the transverse direction (TD) sample. Furthermore, the LPSO phase and grain refinement after extrusion provided a denser corrosion product film to retard the degradation rate in the TD sample. A high mechanical properties Mg-5.6Dy-3.1Ni alloy with different degradation rates in the as-cast, heat-treated, and along the extrusion direction and in the transverse direction was developed. • Developed a high strength Mg-Dy-Ni alloy with different corrosion rates by different process conditions. • The mechanism of microstructure evolution on the degradation rate of high-strength Mg-Dy-Ni alloy was elucidated. • The study alloy meet the fracturing tools with high strength and different degradation time demand. [ABSTRACT FROM AUTHOR]

Dissoluble magnesium alloys for fabrication of fracturing tools have received increasing attention in recent years. However, most of the existing research is focused on the small-sized samples prepared in the laboratory, and there is almost no report on the industrial dissoluble magnesium alloys. In this study, large-scale Mg-Al-Zn-Mn-Ca-Ni alloys with a diameter of 110 mm were prepared by a semi-continuous casting and two-step extrusion method, and the corresponding microstructure and mechanical and corrosion properties were also investigated. It was found that after two-step extrusion, the mainly precipitate phases in the Mg-Al-Zn-Mn-Ca-Ni alloy are bulk-like AlMnNi, strip-like Al3Ni, and granular-like and lamellar-like Mg17Al12 phases. Due to the combined effects of grain refinement and precipitation strengthening, the Mg-Al-Zn-Mn-Ca-Ni alloy obtained excellent mechanical properties after two-step extrusion, and its ultimate tensile strength, yield strength, and elongation were 314.6 MPa, 191.2 MPa, and 13.1%, respectively. Moreover, the corrosion rate of the alloy in 3 wt.% KCl at 93 °C was as high as 97.61 mg·cm−2·h−1. This work provides a high-performance, low-cost, and large-scale alloy product for the fabrication of dissoluble fracturing tools.

The effect of the Ca2Mg6Zn3 phase on the corrosion behavior of biodegradable Mg-4.0Zn-0.2Mn-xCa (ZM-xCa, x = 0.1, 0.3, 0.5 and 1.0 wt.%) alloys in Hank’s solution was investigated with respect to phase spacing, morphology, distribution and volume fraction. With the increase in Ca addition, the volume fraction of the Ca2Mg6Zn3 phase increased from 2.5% to 7.6%, while its spacing declined monotonically from 43 μm to 30 μm. The Volta potentials of secondary phases relative to the Mg matrix were measured by using scanning kelvin probe force microscopy (SKPFM). The results show that the Volta potential of the intragranular spherical Ca2Mg6Zn3 phase (+109 mV) was higher than that of the dendritic Ca2Mg6Zn3 phase (+80 mV). It is suggested that the Ca2Mg6Zn3 acted as a cathode to accelerate the corrosion process due to the micro-galvanic effect. The corrosion preferred to occur around the spherical Ca2Mg6Zn3 phase at the early stage and developed into the intragranular region. The corrosion rate increased slightly with increasing Ca content from 0.1 wt.% to 0.5 wt.% because of the enhanced micro-galvanic corrosion effect. The decrease in the phase spacing and sharp increase in the secondary phase content resulted in a dramatic increase in the corrosion rate of the ZM-1.0Ca alloy.

The influence of various Ag contents on the microstructure, mechanical properties, and corrosion behavior of extruded Al-4.0Cu-1.1Li-0.4Mg-xAg-0.2Mn-0.2Zr (x = 0.4 and 0.9, wt.%) alloys was investigated. The alloy with 0.9 Ag content contains higher number density of slender T1 (Al2CuLi) precipitates along with some θ’ (Al2Cu) phases in the matrix than the alloy with 0.4 Ag content, which is associated with a more rapid hardening response and higher mechanical properties and corrosion resistance, particularly for aging at 130 °C. When aging at high temperatures (above 160 °C), the increase of Ag content mitigates hardness loss by preventing the T1 precipitates from coarsening, and makes the alloy decorate more coarse precipitates at grain boundaries, which leads to the fracture morphology mainly occupied by intergranular fracture. Furthermore, due to the simultaneous promotion of T1 precipitates at grain boundaries and in grain interiors, the 0.9 Ag-containing Al-Cu-Li-Mg-Ag alloy has almost no improvement in corrosion resistance.

Selective laser melting (SLM) of biodegradable metallic materials offers a great potential for manufacturing customized implants. Herein, SLM processing of a novel Fe–30Mn–1C–0.02S twinning‐induced plasticity (TWIP) alloy and the resulting structural, mechanical, and corrosion properties are presented. The occurring rapid solidification results in a fine‐grained austenitic microstructure with mainly homogeneous element distribution, which is investigated by scanning electron microscopy (SEM) combined with energy‐dispersive X‐ray spectroscopy (EDX) and electron backscatter diffraction (EBSD) as well as X‐ray diffraction (XRD). By processing the alloy via SLM, significantly higher strengths under tensile and compressive load in comparison with those for the as‐cast counterpart and a 316L reference steel are achieved. Electrochemical corrosion tests in a simulated body fluid (SBF) indicate a moderate corrosion activity, and a beneficial uniform degradation is shown in immersion tests in SBF. Regarding the envisaged application for vascular implants, SLM‐processed stent prototypes out of the novel alloy are presented and a first functionality test is shown. [ABSTRACT FROM AUTHOR]

Cost‐effective macroporous alumina–mullite membrane supports are fabricated by sintering coarse α‐alumina and colloidal silica, using cornstarch as the foaming agent at 1550 °C for 2 h in air atmosphere. To evaluate the corrosion resistance of such membrane supports, the corrosion behaviors of the supports before and after corroding in the H2SO4 and NaOH solutions (80 °C) are systematically investigated. Interestingly, with increasing Al2O3/SiO2 ratio, the support presents numerous alumina grains and little glass phases, resulting in excellent corrosion resistance especially in acidic media. Benefiting from the alumina grains and little glass phases among the grain boundaries, lower mass loss, less variations in pore size and porosity, high residual strength, and an almost unchanged gas flux are obtained for a higher Al2O3/SiO2 ratio support. The porous support, herein, is suitable for microfiltration membranes used in harsh environments. [ABSTRACT FROM AUTHOR]

The electrolytic hydrogen precharging process is used to analyze the influence of hydrogen on the microstructure, corrosion resistance, and mechanical properties of pure titanium. The results demonstrate that two types of titanium hydrides (δ‐TiHx and ϵ‐TiH2) are detected by electron backscatter diffraction (EBSD), and the volume fraction of titanium hydrides, the local strain caused by hydrogen precipitation, and the thickness of hydrides layer increase with the increase in precharging time. It is noteworthy that the formation of hydrides layer has a protective effect on general corrosion, but the local strain caused by hydrides precipitation leads to the destruction of corrosion resistance, as a result the corrosion resistance of pure titanium increases first and then decreases with the increase in hydrogen precharging time. Moreover, with the precipitation of hydrides, the fracture mode changes from ductile failure to duplex‐ and multimode failure, resulting in the decrease in ultimate tensile strength (UTS) and elongation. Therefore, the mechanical and electrochemical properties of the precharged samples first increase and then decrease with the increase in precharging time, reaching their optimum values at 10 h, and the critical precharging time is determined to be 75 h when comparing those properties with pure titanium. [ABSTRACT FROM AUTHOR]

The effect of synergistic reinforcement of two types of carbon nanofillers, carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), on the corrosion behavior of plasma‐sprayed alumina (Al2O3) nanocomposite coating in 3.5 wt% NaCl solution is studied. Incorporation of 1 wt% CNT and 0.5 wt% GNP into the Al2O3 matrix reduces the corrosion current density of the matrix from 2.78 to 0.21 μA cm−2, which drastically leads to a 13 times reduction in the corrosion rate of the Al2O3 matrix as compared with pure Al2O3 coating. The plausible reasons to this improvement are characterized by the filling of gaps, crevices, and microholes in the Al2O3 matrix by CNTs and GNPs and hydrophobic nature as well as chemical inertness of these reinforcements to the aggressive environment. Further, the corrosion products are analyzed by X‐ray diffraction and Raman spectroscopy for a much deeper insight into the mechanism of corrosion protection by these carbonaceous reinforcements. For the first time, the effect of CNT and GNP reinforcement on the corrosion behavior of plasma‐sprayed coatings is investigated. [ABSTRACT FROM AUTHOR]

Mg 17 Al 12 - x Ce (x = 0, 0.1, 0.5, 1 wt%) intermetallic compounds have been prepared by vacuum induction melting, in order to enhance the corrosion resistance of Mg 17 Al 12 compound by Ce modification. The results have showed that the Mg 17 Al 12 compound compose of β -Mg 17 Al 12 substrate and eutectic structure (α-Mg and β -Mg 17 Al 12 phases) distributed continuously along grain boundaries under non-equilibrium solidification conditions. A high cathode to anode area ratio of the eutectic structure results in poor corrosion resistance of the Mg 17 Al 12 compound. The eutectic structure distributed continuously along the grain boundaries can be interrupted and corrosion could not propagate along the grain boundaries in Mg 17 Al 12 compound alloyed by 0.1 wt% Ce. Hence, the corrosion performance of Mg 17 Al 12 compound has been improved by 0.1 wt% Ce. With the Ce content further increasing to 0.5 wt%, the corrosion resistance of the compounds could be effectively improved due to the formation of dense corrosion products film. Additionally, the complete suppression of eutectic structure effectively reduces electrochemical corrosion of compounds containing more than 0.5% Ce. On the contrary, due to the precipitation of more Al 11 Ce 3 phase, the corrosion resistance of Mg 17 Al 12 –1Ce alloy is slightly deteriorated based on the galvanic corrosion mechanism. • Corrosion behaviors of Mg 17 Al 12 - x Ce compounds were investigated. • Mg 17 Al 12 -0.5Ce alloy exhibit the best corrosion resistance. • The α -Mg was suppressed to improve corrosion resistance of the compounds. • Ce oxide/hydroxide played a major role in the corrosion resistance of Mg 17 Al 12 - x Ce compounds. [ABSTRACT FROM AUTHOR]

β-Type Ti alloys have been widely investigated as implant materials owing to their excellent mechanical properties, corrosion resistance, and biocompatibility. In the present work, the effects of Zr on the microstructure, mechanical properties, and corrosion behaviors of Ti-Zr-Mo-Mn alloys were systematically studied. With the increase of Zr content, the phase composition gradually changed from intragranular-α + β of (TZ) 5:1 MM alloy to grain-boundary-α + β of (TZ) 2:1 MM alloy and finally transferred to a single β phase structure of (TZ) 1:1 MM alloy. The (TZ) 1:1 MM alloy exhibited a good mechanical combination with a yield strength of 750.8 MPa, an elastic modulus of 61.3 GPa, and a tensile ductility of 14.6%. Moreover, the addition of Zr can effectively stabilize the passivation film and reduce the sensitivity of microgalvanic corrosion in simulated body fluid, leading to enhanced corrosion resistance in the TZMM alloys. X-ray photoelectron spectroscopy analysis together with the ion-sputtering technique revealed that the passivation films formed on TZMM alloys possessed a bilayered structure (outer Ti+Zr mixed-oxide layer and inner Zr-oxide-rich layer), in which the inner Zr oxide layer plays an important role in the corrosion resistance of the TZMM alloys. In vitro biocompatibility evaluations demonstrated that the TZMM alloys can support cell adhesion and proliferation with high biocompatibility comparable to that of CP-Ti, while in vivo biocompatibility evaluations validated the bone osteointegration ability of TZMM alloys after long-term implantation. The above results indicate that novel TZMM alloys are promising candidates for implant material.

Recently much attention has been paid to high-entropy alloy thin films (HEATFs) due to their excellent physical and chemical properties. Simultaneously, pulsed laser deposition (PLD) is an increasingly focused method for thin film preparation due to its remarkable advantages. In this study, CoCrFeNiAl 0.3 HEATFs were prepared on silicon substrates in a high vacuum chamber at room temperature for different deposition time by PLD. The microscopic morphologies, chemical composition, elastic modulus, nanohardness and corrosion behaviors of the CoCrFeNiAl 0.3 HEATFs were systematically investigated. The microscopic morphology shows that there are some nanoscale granules on the surface of the HEATFs. The nanoindentation results indicated that the CoCrFeNiAl 0.3 HEATFs have higher nanohardness but lower elastic modulus than the bulk counterparts. With increasing the deposition time, elastic modulus and nanohardness become higher initially and then decrease, which reaches at highest as the deposition time for 2 h. Corrosion behaviors experiments verified that CoCrFeNiAl 0.3 HEATFs have higher corrosion resistance than 316 L stainless steel in NaCl solution. Our results could provide a new advanced method for preparing HEATFs, and in-depth understanding the mechanics and corrosion behaviors of HEATFs for future application. • CoCrFeNiAl0.3 high-entropy alloy thin films were successfully prepared by pulsed laser deposition. • The high-entropy alloy thin films are considerably smooth with strong mirror effect. • The nanohardness of the high-entropy alloy thin films is nearly 3 times higher than the bulk forms. • Corrosion resistance of the high-entropy alloy thin films is better than 316L stainless steel. [ABSTRACT FROM AUTHOR]

Plasma immersion ion implantation (PIII) was studied as a pretreatment method for improving the surface activity of TiN coatings deposited by high power impulse magnetron sputtering (HiPIMS) before being sealed with an ALD (Atomic layer deposition)-Al 2 O 3 hybrid coating. The effect of different implantation energy and dose of nitrogen plasma on the microstructure and surface morphology of TiN coatings were investigated, and the surface morphology and fracture cross-section images of TiN/Al 2 O 3 hybrid coatings with and without PIII pretreatment were compared. The corrosion protection properties were explored with linear sweep voltammetry in 3.5% NaCl solution at the room temperature. The results indicated that the N+ pre-ion-implantation had a significant influence on the microstructure and surface morphology of TiN coatings. With the increase of ion implantation energy and dose, TiN coatings gradually alter from the preferred orientation (200) to a mixture of (200) and (111), accompanied by the decrease of grain size on the surface. Moreover, the PIII pretreatment of the TiN coatings could significantly shorten the incubation time of the nucleation of ALD films, leading to a denser but thinner (at the same deposition cycles) layer of Al 2 O 3 , which plays a positive role in corrosion resistance. The coverage of ALD-Al 2 O 3 films was improved with the increase of the nitrogen ion implantation energy and dose, resulting in better corrosion protection. • The TiN/Al 2 O 3 hybrid coatings were designed and deposited by combining HiPIMS, PIII, and ALD. • The N+ ion-implantation has significant influences on the microstructure and surface morphology of TiN coatings. • The PIII pretreat the TiN coatings cloud significantly shorten the incubation time of the nucleation of ALD films. • The corrosion performance of hybrid coatings was improved with the increase of the N+ ion implantation energy and dose. [ABSTRACT FROM AUTHOR]

Summary: In this work, the role of Al2Ca and Al2(Sm,Ca,La) particles in the microstructures and electrochemical discharge performance of the as‐extruded Mg‐3wt.%Al‐1wt.%Zn‐based alloys has been reported and discussed for the anode design of Mg‐air batteries. The Al2Ca and Al2(Sm,Ca,La) particles strongly refine the grains of the as‐extruded AZ31 alloy from 9.1 ± 4.1 μm down to 5.1 ± 3.3 μm. The Al2Ca and Al2(Sm,Ca,La) particles increase the outputting cell voltage and discharge capacity of the modified AZ31 alloy. The AZ31‐Ca alloy exhibits the highest discharge capacity and anodic efficiency of 1153 mAh/g and 52.5%, respectively, at 10 mA/cm2. The promoted discharge performance should be mainly attributed to the grain refinement (improving the corrosion resistance) and fine Al2Ca phase throughout the matrix (beneficial for uniform dissolution of Mg phase). Additional Al2(Sm,Ca,La) cubic particles further stimulate the anodic kinetics and aggravate the local dissolution of Mg phase near around, resulting in the deterioration of discharge performance. [ABSTRACT FROM AUTHOR]