Mechanical and corrosion properties of Al + 20 vol% (TiC + TiB
2
) composites containing different amounts of MWCNTs produced by mechanical alloying and spark plasma sintering processes were ...investigated. X-ray diffraction analysis was used to identify the formation of the different phases. Field emission scanning electron microscopy equipped with EDS was utilized for microstructural studies. The Young's modulus and hardness of the composites were evaluated by nanoindentation test. The corrosion behavior of samples was investigated by polarization and impedance tests. X-ray diffraction analysis showed that TiC and TiB
2
phases were formed during the mechanical alloying. The results of microstructural studies showed that the reinforcement particles were completely dispersed in the aluminum matrix. Also, it was found that the maximum hardness and the maximum Young's modulus belonged to the composite sample containing 1 wt% of MWCNTs. The highest corrosion resistance was also observed in the sample containing 1 wt% of MWCNTs.
Graphical abstract
Friction stir welding (FSW) and friction stir processing (FSP) are two of the most widely used solid-state welding techniques for magnesium (Mg) and magnesium alloys. Mg-based alloys are widely used ...in the railway, aerospace, nuclear, and marine industries, among others. Their primary advantage is their high strength-to-weight ratio and usefulness as a structural material. Due to their properties, it is difficult to weld using traditional gas- or electric-based processes; however, FSW and FSP work very well for Mg and its alloys. Recently, extensive studies have been carried out on FSW and FSP of Mg-based alloys. This paper reviews the context of future areas and existing constraints for FSW/FSP. In addition, in this review article, in connection with the FSW and FSP of Mg alloys, research advancement; the influencing parameters and their influence on weld characteristics; applications; and evolution related to the microstructure, substructure, texture and phase formations as well as mechanical properties were considered. The mechanisms underlying the joining and grain refinement during FSW/FSP of Mg alloys-based alloys are discussed. Moreover, this review paper can provide valuable and vital information regarding the FSW and FSP of these alloys for different sectors of relevant industries.
•Mechanical, tribological, corrosion behavior, biocompatibility and antibacterial activity of Mg additively manufacturing are presented.•Different AM processes and post-processes treatments for Mg ...alloy are reviewed and summarized.•Benefits and restrictions of the Mg additively manufacturing are introduced.•The latest development of Mg additively manufacturing for industrial applications is presented.•Toughening mechanism and antibacterial mechanism Mg additively manufacturing is introduced.
Magnesium (Mg)-based materials are a new generation of alloys with the exclusive ability to be biodegradable within the human/animal body. In addition to biodegradability, their inherent biocompatibility and similar-to-bone density make Mg-based alloys good candidates for fabricating surgical bioimplants for use in orthopedic and traumatology treatments. To this end, nowadays additive manufacturing (AM) along with three-dimensional (3D) printing represents a promising manufacturing technique as it allows for the integration of bioimplant design and manufacturing processes specific to given applications. Meanwhile, this technique also faces many new challenges associated with the properties of Mg-based alloys, including high chemical reactivity, potential for combustion, and low vaporization temperature. In this review article, various AM processes to fabricate biomedical implants from Mg-based alloys, along with their metallic microstructure, mechanical properties, biodegradability, biocompatibility, and antibacterial properties, as well as various post-AM treatments were critically reviewed. Also, the challenges and issues involved in AM processes from the perspectives of bioimplant design, properties, and applications were identified; the possibilities and potential scope of the Mg-based scaffolds/implants are discussed and highlighted.
In this research, the effect of different bonding times on the microstructure and mechanical properties of the WC-Co/St52 joint created by the transient liquid-phase process at 1200°C using copper ...interlayer was investigated. For this purpose, bonding times of 1, 15, 30, and 45 min were used. The microstructure of the bonded samples was examined using an optical microscope as well as scanning electron microscope equipped with energy-dispersive X-ray spectroscopy. Microhardness and tensile-shear strength tests were carried out to evaluate the mechanical properties of the joints. The results showed that there were two main zones of isothermal and athermal solidification in the bonding region, which determined the properties of the bonding samples. The isothermal solidification zone contained a Fe-rich solid solution, which increased its volume fraction with increasing the bonding time. The athermal solidification zone also contained a Cu-rich solid solution phase. The presence of Fe-rich solid solution in the centerline of the all joints caused the same hardness in all joints. The maximum tensile-shear strength was related to the sample with bonding time of 15 min, because of the proper continuity in the microstructure and presence of optimal amount of Cu-rich solid solution phase in microstructure.
A Sm
2
Co
17
permanent magnet was successfully transient liquid phase bonded using AWS BNi-2 interlayer at 1100 °C for 60 min. Microstructural evolutions and chemical composition changes after TLP ...bonding of the samples were analyzed using optical microscopy, scanning electron microscopy and energy-dispersive spectroscopy. The changes of magnetic properties of the base material due to the TLP process were evaluated using vibrating sample magnetometry. It was found that the bonded sample by 50-μm-thick interlayer foil majorly contained athermally solidified zone and brittle second phase, indicating that the bonding time is not sufficient for joining, while the bonded sample by 25-μm-thick foil was almost solidified isothermally. Also, the results showed that a considerable increase in coercivity, remanence and also maximum energy product was occurred after TLP bonding of Sm
2
Co
17
permanent magnet. This increase was mainly attributed to the strong magnetic exchange coupling between FeCo- and Fe-rich borides (as soft magnets) and Sm–Co matrix (as hard magnet).
In 1992, Frankel and Desmedt introduced a technique that enables one to reduce the secret space of an ideal homomorphic secret sharing scheme (IHSSS) into any of its characteristic subgroups. In this ...paper, we propose a similar technique to reduce the secret space of IHSSSs called the quotient technique. By using the quotient technique, we show that it is possible to yield an ideal linear scheme from an IHSSS for the same access structure, providing an alternative proof of a recent result by Jafari and Khazaei. Moreover, we introduce the concept of decomposition of secret sharing schemes. We give a decomposition for IHSSSs, and as an application, we present a necessary and sufficient condition for an IHSSS to be mixed-linear. Continuing this line of research, we explore the decomposability of some other scheme classes.
Ferritic–martensitic dual-phase (DP) steels are prominent and advanced high-strength steels (AHSS) broadly employed in automotive industries. Hence, extensive study is conducted regarding the ...relationship between the microstructure and mechanical properties of DP steels due to the high importance of DP steels in these industries. In this respect, this paper was aimed at reviewing the microstructural characteristics and strengthening mechanisms of DP steels. This review article represents that the main microstructural characteristics of DP steels include the ferrite grain size (FGS), martensite volume fraction (MVF), and martensite morphology (MM), which play a key role in the strengthening mechanisms and mechanical properties. In other words, these can act as strengthening factors, which were separately considered in this paper. Thus, the properties of DP steels are intensely governed by focusing on these characteristics (i.e., FGS, MVF, and MM). This review article addressed the improvement techniques of strengthening mechanisms and the effects of hardening factors on mechanical properties. The relevant techniques were also made up of several processing routes, e.g., thermal cycling, cold rolling, hot rolling, etc., that could make a great strength–ductility balance. Lastly, this review paper could provide substantial assistance to researchers and automotive engineers for DP steel manufacturing with excellent properties. Hence, researchers and automotive engineers are also able to design automobiles using DP steels that possess the lowest fuel consumption and prevent accidents that result from premature mechanical failures.
Welding of AISI H13 tool steel which is mainly used in mold making is difficult due to the some alloying elements and it high hardenability. The effect filler metal composition on the microstructural ...changes, phase evolutions, and hardness during gas tungsten arc welding of AISI H13 hot work tool steel was investigated. Corrosion resistance of each weld was studied. For this purpose, four filler metals i.e. ER 312, ER NiCrMo-3, ER 80S, and 18Ni maraging steel were supplied. Potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) were used to study the corrosion behavior of weldments. It was found the ER 80S weld showed the highest hardness owing to fully martensitic microstructure. The hardness in ER 312 and ER NiCrMo3 weld metals was noticeably lower than that of the other weld metals in which the microstructures mainly consisted of austenite phase. The results showed that the corrosion rate of ER 312 weld metal was lower than that other weld metals which is due to the high chromium content in this weld metal. The corrosion rate of ER NiCrMo-3 was lower than that of 18Ni maraging weld. The obtained results from EIS tests confirm the findings of potentiodynamic polarization tests.
The effect of bonding temperature and bonding time on the microstructure of transient liquid phase (TLP) bonding named GTD111 and IN718 superalloys, using a commercial Ni–B–Cr filler alloy (BNi-2) ...interlayer were evaluated. The sandwich assembly was kept in a vacuum furnace at temperatures of 1050, 1100, and 1150 °C for 1, 15, 30, 45, 60, and 80 min until the TLP process occurred. Microstructural characterization was carried out via optical microscopy, scanning electron microscopy (SEM) equipped with field emission energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Microstructural assessments displayed those in little bonding times, the joint microstructure includes continuous eutectic intermetallic phases and longer times cause eutectic free microstructure. The bonding temperature affects the isothermal solidification rate, while, at low bonding temperatures microstructure of the joint centerline is controlled by diffusion of melting point depressant (MPD) elements. Despite, at high bonding temperature effect of base metal alloying elements on the joint microstructure development was more marked. The results showed that athermally solidified zone (ASZ) size reduces with increasing bonding temperature and time due to diffusion of boron into the base metal.
Semiconductors as photocatalysts are ideal materials for wastewater remediation. A nanocomposite of g–C3N4 and ZnO was produced using a two-step in situ synthesis technique to achieve a better ...photocatalyst. The samples were assessed via UV–vis diffuse reflection spectroscopy, transmission electron microscopy, photoluminescence spectroscopy, Fourier transform infrared analysis, and x-ray diffraction. The photodegradation of methylene blue as an organic dye model was assessed to assess the photocatalytic characteristics of the fabricated samples. The antibacterial characteristics of synthesized samples were also investigated. The findings revealed that the photodegradation efficiency of the binary g–C3N4/ZnO systems was better than that of pure g–C3N4. Under irradiation, the photodegradation yield of g–C3N4/ZnO with a 15 wt.% of ZnO was up to 3.5 times better than that of pristine g–C3N4. The feature of enhanced separation of photoinduced holes and electrons resulting from heterojunction creation among g–C3N4 and ZnO surfaces might be attributed to this photocatalytic activity enhancement. The synthesized binary nanocomposites showed suitable antibacterial properties against Staphylococcus aureus and Escherichia coli bacteria.
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