Search

Additive manufacturing (AM) of Mg alloys has become a promising strategy for producing complex structures, but the corrosion performance of AM Mg components remains unexploited. In this study, wire and arc additive manufacturing (WAAM) was employed to produce single AZ31 layer. The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation, similar phase composition and stabilized corrosion performance comparing to the cast AZ31. These varied corrosion behaviors were principally ascribed to the size of grain, where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion, respectively.

Machines are integral part of industrial concerns and establishments. Tools are the backbone of machinery and vary according to the application they are being put used to as well as the end product required. Tool wear, on a comparative scale, is more predominant factor in cutting applications. This may be attributed towards a number of factors such as the high temperature arising at the cutting junction, frictional forces being generated; feed rate etc. Conventional methods utilize various alternatives such as lubricants in the form of grease, oil etc. and specially designed cooling fluids. In spite of their beneficial functions, they tend to provide health hazard due to consequent environmental pollution. By using minimum quantity lubrication system, it saves 50% of coolant which done for machining and also reduce environmental problems. In silicon carbide nano additive gives least metal removal rate compared with copper oxide and titanium oxide.

The relationship among the microstructure, hardness and electrical conductivity of the as-forged ZYK530 Mg alloy after heat treatment was analyzed and studied using a microscope, X-Ray Diffractometer, eddy current conductivity meter, and Vickers microhardness tester, to explore optimum heat treatment process of ZYK530 Mg alloy. The results show that: with the prolongation of holding time, the electrical conductivity and microhardness show the same change trend, both of which show an oscillatory upward trend, and then decrease in an oscillatory downward trend after reaching the peak value. There is a linear positive correlation between the conductivity and the hardness, and the fitting results of the conductivity and hardness are in good agreement with the measured results; combined with the actual production, when the heat-treatment is 480 ℃ × 8 h + 220 ℃ × 3 h, the highest hardness is 79.2 HV, the electroconductivity is 36.2%IACS, and the comprehensive performance is the best, which is the best heat treatment process.

Specific gravity segregation that occurs during the smelting process always leads to the low composition homogeneity and poor performance stability of the magnesium-rare earth (Mg-RE) alloys. In this study, the segregation behavior of Mg-Gd alloy was investigated by sampling from different locations in the ingot fabricated by a resistance furnace without a pouring process. The combined application of induction-heating and mechanical stirring with various speeds (0–130 r/min) was applied to promote the distribution homogeneity of Gd atoms. In the resistance-heating fabricated ingot, Gd content at the bottom section reaches 407% of that at the top. The coarse dendrites surrounded by the network-like eutectic structures are responsible for the brittle fracture with a poor elongation of 3.7%. By the combined employment of the induction heating and mechanical stirring with the speed of 87 r/min at 740 °C for 40 s, the variation of the Gd content within the whole ingot can be reduced to be the minimum of 0.23 wt%. Corresponding formation and regulating models of segregation were also proposed. However, the cooling rate of the melt is reduced by the continuous increase of the stirring speed to 130 r/min, which results in the grain coarsening and lower homogeneity of the ingot.

Wet etching is a micromachining process in which a material is immersed in liquid chemicals or etchants to remove unwanted sections from the surface. The process is generally known as cost-effective, reliable and suitable for high-production environments. Magnesium alloys are presenting a strong popularity in recent years since it is one of the lightest engineering alloys. Hence, the micromachining of these materials is becoming an important research area. One of the promising methods is wet etching. In this experimental study, two different concentrations (10 and 20 ml) of a nitric acid solution are used at room temperature. The wet etching characteristics of a selected magnesium alloy is determined by analysing the thickness reduction and surface roughness as well as colour degradation on the machined surfaces.

Magnesium alloys have a significant benefit over the steel and aluminum alloys in manufacturing of components for many automotive and structural applications because of their extreme lightweight, low density, and high strength to weight ratio. However, one of the glaring impediments to the success of steels, aluminum, and magnesium-based multi-material integration for automotive industries is the ability to join these materials together without any cracking and corrosive damages during a performance. The present work aims to demonstrate a cost-effective, novel, and versatile joining technique, named Upset Protrusion Joining (UPJ), to mechanically and rapidly (1-2 seconds) join die-cast AM60 alloy to aluminum alloy sheet and evaluate its UPJ characteristics. Cast Mg plate has a cylindrical protrusion (11 mm diameter and 14 mm height) emanated perpendicular to its flat surface, and an aluminum sheet has a hole that accommodates the protrusion. Mg and Al alloy components are then clamped together, electrically heated, and compressed perpendicular to the protrusion axis. During compression, the protrusion expanded circumferentially to fill the hole as well as the region above the hole, and entrapped the Al sheet between the deformed (in a mushroom shape) head and the Mg plate. The effect of different UPJ process parameters such as applied current, current duration, compression loading rate, and compression distance is studied. The process demonstrated repeatability at given process conditions, and optimum process parameters were identified that produce visibly good joints (defect-free) and sufficient joint strengths when tested in the lap-shear mode under uniaxial tension. AM60 alloy showed a great promise as a candidate alloy to suit the UPJ method to adapt to automotive and other industrial manufacturing units to join with dissimilar wrought Al alloy sheets.

Corrosion of magnesium (Mg) is generally manifested by cathodic hydrogen gas evolution and concomitant anodic Mg dissolution. The surface condition significantly modified the corrosion of Mg, especially related to the deformation. The corrosion behaviour of AZ31 Mg alloy with emphasis on surface condition effect has been investigated. Filiform-like corrosion was observed significantly along the grinding path due to surface modification by mechanical grinding. From the cross-section characterization, the corrosion attack into the crystallographic structure. The analysis of corrosion behaviour is based on the polarization behaviour during the electrochemical measurement and scanning vibration electrode technique (SVET) measurement for local electrochemical quantification. Cathodic filiform body with Mg(OH)2 formation promoted the anodic corrosion propagation. Thick non-protective corrosion product formed after a longer immersion period was associated with uniform pitting propagation tunneled underneath the alloy, confirming the autocatalytic cathodic activation.

Although having suitable mechanical properties, the high corrosion and resorption rate of biocompatible Mg alloys make them unsuitable for implant applications. Reducing the corrosion rate of the alloys by altering the metallurgical properties can be potentially beneficial for such applications. Friction stir processing (FSP) is an established process to induce changes in the surface microstructure of metals, and in this study, this process has been explored as a potential method to modify the metallurgical microstructure of the alloy. There is an increase of 13 % of microhardness and there is a 21 % reduction in ultimate stress in exchange of 15 % increase in % elongation in friction stir processed AZ31 magnesium alloy. The results indicate that the induced changes in the metallurgical microstructure by FSP process can augment the resistance to corrosion without significantly deteriorating the mechanical properties as observed from tests conducted in a simulated biological environment. Further experimentation is required to optimize the processing condition and establish the relationship between the evolved metallurgical microstructures and the mechanical and electrochemical properties.

This present research paper discusses about the fabrication of metal matrix composite coating on AZ31B magnesium alloy substrate with Al, Co and TiN mixed precursor powders by gas tungsten arc (GTA) cladding process. Firstly, Co and TiN powders were mixed properly in the ratio of 1:1. Thereafter, three samples with different compositions of 20 wt% (Co + TiN)), 25 wt% (Co + TiN)), 30 wt% (Co + TiN)) and balance aluminium powder were developed by preplaced technique. The samples were heated by TIG torch at the optimized parameter as current of 110 Amp, voltage of 25 V, welding speed of 4.23 mm/s and thermal energy of 3.12 kJ/cm. After melting and solidification metallurgical bonding between coating and substrate occurs. The microstructure and chemical composition of the coated samples were analysed by field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) respectively. The micro hardness of coated samples were analysed by Vickers micro hardness testing. It was found that with increase in percentage content of Co + TiN the amount of microhardness increases. Furthermore, it was found that the value of maximum microhardness was 422 HV0.1, which was nearly seven times higher than that of the magnesium alloy substrate (64 HV0.1).

The lightest structural metal present on Earth’s surface is Magnesium (Mg). Mg is very useful for many applications like automobile, aeronautical etc. Mg has many limitations and because of which it cannot be used directly as a replacement of steel and aluminum. Different alloys of magnesium have been developed to partially or completely overcome the limitations of magnesium without sacrificing other properties. The most commonly used commercial alloys are in almost all the fields is magnesium alloy AZ91, which gives better properties than magnesium. This paper mainly aims at study the mechanical properties of magnesium based AZ91 alloy. The results were compared with the as-cast condition. Present investigated material has been obtained by using die casting technique. Mg material is subjected to T6 heat treatment which has two stage process involving combination of solution annealing at 413 °C for 13 h and subsequent aging at 200 °C for 10 h. Micro structural and mechanical properties like hardness of the specimen were studied. Useful survey shows that hot working of AZ91 alloy provides high mechanical properties unattainable by cast material subjected to heat treatment. The microstructure is observed under the optical microscope.

This paper discusses about the recent advancements in laser cladding and alloying processes used for surface property enhancement of magnesium and its alloys. Laser cladding and alloying is advanced manufacturing method used for surface modification of metallic materials in the modern industries. The cladding process is surface modification technique, which is used for deposition of thick layer of advanced materials on surface of conventional materials to improve the surface properties like, wear resistance, hardness, oxidation resistance, corrosion resistance, biocompatibility and heat resistance. The advanced materials generally used for cladding operations are transition metals, alloys, ceramics, composites, nanomaterials, rare earth oxide and some solid lubricant additives. The conventional substrate materials are steel, cast iron, titanium alloy, aluminium alloy, magnesium alloys and copper alloys. Laser cladding is most widely used coating technique because of its attractive properties such as low dilution rate, good metallurgical bonding between coating and substrate, less distortion, narrow heat affected zone, high solidification and cooling rate. In this article magnesium alloy is considered as substrate material and the various coating materials used for its surface modification are explained. Also, the effects of various laser process parameters on phase composition, microstructure, elemental composition, mechanical properties, tribological properties and corrosion resistance are discussed. The characterization techniques such as XRD, SEM, EDS, Vickers microhardness test, wear and friction test, corrosion test used for coating analysis are described. Furthermore, the problem arises in laser cladding and alloying on magnesium alloy and their possible remedies are discussed.

Process of horizontal twin roll casting magnesium alloy was analyzed by numerical simulation. Taking solidification welding line in cast rolling area as research object, the characteristic change of solidification welding line caused by casting rolling temperature, casting rolling speed, and roll heat transfer capacity and its influence on the forming process of casting rolling area were analyzed. The results show that increasing casting temperature, casting speed or reducing heat transfer capacity of roll can make solidification welding line shift to exit of casting rolling zone. Increasing casting temperature and casting speed will increase difference between middle and edge of the solidification welding line along casting direction and heat distribution of whole slab is more uniform. However, effect of improving heat transfer capacity of roll is completely opposite. According to this, optimum process parameters of casting and rolling magnesium alloy with plate thickness of 6 mm are put forward to reduce probability of edge crack.

Lean alloy (low alloyed) is beneficial for long-term sustainable development of metal materials. Creating a nanocrystalline microstructure is a desirable approach to improve biodegradability and mechanical properties of lean biomedical Mg alloy, but it is nearly impossible to realize. In the present study, the bulk nanocrystalline Mg alloy (average grain size: ~70 nm) was successfully obtained by hot rolling process of a lean Mg-2wt.%Zn (Z2) alloy and both high strength ((223 MPa (YS) and 260 MPa (UTS)) and good corrosion resistance (corrosion rate in vivo: 0.2 mm/year) could be achieved. The microstructure evolution during the rolling process was analyzed and discussed. Several factors including large strain, fine grains, strong basal texture, high temperature and Zn segregation conjointly provided the possibility for the activation of pyramidal slip to produce nanocrystals. This finding could provide a new development direction and field of application for lean biomedical Mg alloys., Graphical abstract Image 1, Highlights • The nanograins rounded by Zn atoms segregation are achieved in a lean biodegradable Mg-2wt.%Zn alloy by hot rolling process. • The nanocrystalline Mg–2Zn alloy demonstrates a high strength and good degradation properties. • Microstructures and rolling condition conjointly provided the activation of pyramidal slip to produce nanocrystals in Mg–2Zn alloy.

The uses of magnesium and magnesium alloys in various fields impedes earnestly due to the low corrosion resistant and poor high temperature properties. In this present investigation, the two problems has been noticed and solved; firstly immense chemical activity and secondly the Mg alloys chemical activity has been inhomogeneous on its surface. This work tries to solve those problems by superhydrophobic (SHP) layer on AZ91D Mg alloy. The SHP surface on magnesium alloy with an angle of contact for water greater than 150° and a sliding angle lesser than 10° is a excellent water-repelling ability has been obtained. The present results confirm that this form of SHP coating has definite anti-corrosion effect in typical corrosive solution. The presented method is uncomplicated, cost effective, and environmentally friendly and has enormous potential value in the production of a large-scale industry.

ECAP is a continuous multi-pass extrusion process that enables the specimen to obtain considerable cumulative deformation to refine the grain. In this paper, ECAP was used to deform AS41 magnesium alloy at 350°C, and the microstructure was observed and analyzed. The results show that the ECAP process has excellent effect on grain refinement and uniform microstructure. The grain size of AS41 decreases from 200μm to 20μm, and the microstructure is more uniform than that of as-cast sample. The reason is that the original grain is broken and refined under the action of shear force, and dynamic recrystallization occurs at the same time, resulting in small recrystallized grains. The Mg2Si particles were redistributed during ECAP and uniformly distributed in the crystal in rod shape.

The effect of hot extrusion on the corrosion behavior of AZ91 alloy was studied by observing the change of grain size, the size and distribution of precipitated phase on the transverse and longitud...

This work investigated the corrosion resistance of AZ80 (Mg-8Al-0.5Zn alloy) with different Nd contents in alkaline solution by the mass loss test, electrochemical test, scanning electron microscope, energy spectrum analysis, and x-ray diffraction. To remove the influence of the Mg17Al12 phase, alloys were heat treated at 410°C for 10 h. Results revealed that Al2Nd and AlMnNd phases mainly exist in the alloy. The corrosion rate of the alloy increased when the Nd content was

There is a substantial demand in transportation industries to join dissimilar Al and Mg alloy to reduce the structural weight further. However, it is challenging to produce high-strength joints of Al/Mg even with friction stir welding due to the formation of intermetallic compounds (IMCs). In a quest to suppress/eliminate the IMCs, we propose to add a Ni interlayer in a sandwich form between the Mg and Al plates. Widely used and industrially applicable AA6061-T6 and AZ31B Mg alloys are taken for experimentation in the present study. The Ni interlayer's effects on microstructure, mechanical properties, and IMCs characterization are studied. The Ni interlayer can drastically cease the molecular diffusion of Mg and Al across their interfaces, and typical IMCs Al3Mg2 and Al12Mg17 are eliminated. Significant dispersion of Ni with Al and Mg is found in the weld zone, which forms Al3Ni and Mg2Ni compounds. The energy-dispersive X-ray spectroscopy confirms the efficacy of Ni addition to wipe out the I² and I³ IMCs phases. The localized fracture analysis of Ni interlayered joint suggests dual-mode failure, i.e., ductile and brittle. The mechanical testing advocates better weld quality for Ni interlayered joints compared to its conventional ones. © 2021 The Author(s)

Purpose The purpose of this paper is to study systematically the corrosion behavior of AZ31 magnesium (Mg) alloy with different concentrations of bovine serum albumin (BSA) (0, 0.5, 1.0, 1.5, 2.0 and 5.0 g/L). Design/methodology/approach Electrochemical impedance spectroscopy and potential dynamic polarization tests were performed to obtain corrosion parameters. Scanning electrochemical microscopy (SECM) was used to analyze the local electrochemical activity of the surface film. Atomic force microscope (AFM), Scanning electron microscope-Energy dispersive spectrometer and Fourier transform infrared spectroscopy were used to determine the surface morphology and chemical composition of the surface film. Findings Experimental results showed the presence of BSA in a certain concentration range (0 to 2.0 g/L) has a greater inhibitory effect on the corrosion of AZ31, however, the presence of high-concentration BSA (5.0 g/L) would sharply reduce the corrosion resistance. Originality/value When the concentration of BSA is less than 2.0 g/L, the corrosion resistance of AZ31 enhances with the concentration. The adsorption BSA layer will come into being a physical barrier to inhibit the corrosion process. However, high-concentration BSA (5.0 g/L) will chelate with dissolved metal ions (such as Mg and Ni) to form soluble complexes, which increases the roughness of the surface and accelerates the corrosion process.

Friction stir welding is successfully used to weld different wrought magnesium alloys. This work investigated the mechanical and microstructural behavior of the friction stir-welded AZ31B magnesium alloy. The experiments were conducted as per experimental runs designed by response surface methodology. An artificial neural network model was developed to produce a relationship between process variables (tool rotational speed, welding speed, and tool shoulder diameter) and characteristics of the friction stir-welded joints (tensile strength, percentage elongation, impact strength, microhardness, and grain size). The acceptable range of statistical parameters validated the adequacy of the model. The multi-objective optimization technique, genetic algorithm was used to obtain a set of Pareto optimal solutions. The best-compromised optimum solution for maximum tensile strength (164.2 MPa), percentage elongation (8%) impact strength (3.5 J), microhardness (85 Hv), and minimum grain size (13.1 μm) was validated by confirmation test with

Magnesium alloy sheets have an increasing proportion of applications in automobiles due to their high specific strength. The usability of traditional welding processes and mechanical joining processes is restricted by the characteristic of magnesium alloy sheets. In order to improve the plasticity of magnesium alloy sheets and realize the reliable joining of magnesium alloy sheets with dissimilar sheets, researchers have conducted a lot of research. In this paper, the existing joining processes of friction stir spot welding, friction stir blind riveting, hybrid self-piercing riveting, and friction self-piercing riveting for magnesium alloy sheets are reviewed; the latest advances of joining process are introduced; and the principle, development, advantages, and shortcomings of each process for improving the plasticity of magnesium alloy sheets are systematically described. Several unaddressed issues in the joining of magnesium alloy sheets are identified. The hybrid of mechanical and solid-state joining processes will be a trend in future development.

The use of cryogenic coolants as an alternative cooling technique has been applied widely in recent years because of the many problems associated with conventional cutting fluids. No paper has been published to date on the milling of AZ31 magnesium alloy under dipped cryogenic cooling approach. The comprehensive results from the experimental study have practical importance and provide valuable information for industrial production processes. In this study, milling tests were carried out on AZ31B magnesium alloy under various cutting speeds, feed rates, and depths of cut. During milling, the effects of liquid nitrogen on milling forces, chip formation, and surface roughness were examined and a damage analysis was also carried out. This study introduced a novel cryogenic approach in the milling of AZ31B magnesium alloy using a liquid nitrogen bath. A new experimental setup was prepared for performing milling tests with the approach. Based on the experimental results, it was concluded that using the dipped cryogenic approach improved (approximately 2–34%) the surface quality of the workpiece and provided shorter chip formation. In addition to these, in the tests carried out under dry cutting conditions, lower milling forces (approximately 16–88%) were formed compared to the cryogenic conditions. A surface damage analysis was also performed.

The essential purpose of this review paper is to describe the advancement of work towards dissimilar friction stir welding of Al to Mg alloy. Nowadays, joining dissimilar aluminium and magnesium al...

The thermal stability of the superhydrophobic properties of coatings obtained on a magnesium alloy by plasma electrolytic oxidation (PEO) followed by treatment with fluoropolymer was studied. It was established that formed surface layers have contact angle (CA) equal to 171° and contact angle hysteresis equal to 6° at 25 °C, which allows to characterize them as superhydrophobic. After 5 cycles of cooling-heating of composite layers, CA was 135°, indicating the durability of coatings. Additionally, obtained polymer-containing layers demonstrated low wettability at 0 °C (CA was 105°).

Purpose. Study of the effect of alloying with aluminum on structure formation, mechanical properties and heat resistance of magnesium alloys Research methods. Methods of metallographic and micro X-ray spectral analysis. Determination of mechanical properties and heat resistance. Results. The regularities of the influence of alloying with aluminum on the formation of the hardening phase in magnesium alloys have been investigated. It is shown that an increase in the concentration of aluminum in magnesium alloy promotes refinement of the macro- and microstructure of the metal (reduces the grain size and the distance between the second-order dendritic axes) and also increases the amount of intermetallic phase. The positive effect of aluminum additives on the mechanical properties and heat resistance of cast metal has been established. The optimal level of alloying with aluminum (about 7,7 %) hes been determined, which ensures a sufficient level of mechanical properties and heat resistence. Scientific novelty. Based on the regression analysis of the experimental data, empirical equations were obtained that describe the dependences of the size of macro- and micrograins on the concentration of aluminum in magnesium alloys. It is shown that the optimal aluminum content in the magnesium alloy in the amount of ~ 7,7 % provides the best combination of mechanical properties (a sufficiently high strength and the highest plasticity) and heat resistance Practical value. It has been established that alloying magnesium alloys with aluminum is promising for improving the structure and increasing the mechanical properties and heat resistance of cast metal. This effect makes it possible to significantly expand the field of application of magnesium alloys in mechanical engineering and improve the performance of various equipment.

Hot deformation behaviour of as-extruded Mg–5Gd–2.5Nd–0.5Zn–0.5Zr alloy was investigated using compression test at a temperature range of 350–500°C and strain rates of 0.001–1 s−1. Microstructural ...

Wire-based friction stir processing is introduced as a solid-state surface alloying strategy for surface alloying of AZ31 magnesium alloy with aluminum, as a key alloying element in magnesium alloys. This technique enables the formation of a defect-free, grain refined and alloyed surface with the increased volume fraction of Mg-Al second phase, and thus, enhanced surface hardness. This simple technique provides a solid-state surface alloying pathway to improve the surface properties of the metallic materials.

To enhance the damage and corrosion behaviour for alloys, the coating is found because of the maximum fitted technique. Mg-based alloys have a good range of business application. These alloys show a high specific strength but bad attire and corrosion resistance. A standard coating of Cu, Ni & Zn etc. provides a physical barrier against the wear and tear rate and corrosion attack of magnesium substrate. In the recent study, plating Ni-P was thru going on AZ91 composite by immersing samples into Nickel sulphate bath in the existence of surfactants. The study of the mechanism of Ni-P deposits was studied utilizing SEM. Ni-P coating was coated consistently within the existence of surfactants. Result of surfactant and Result of Nano-additives ZnO, Al2O3 and SiO with various quantities were examined. 0.5 g/l Nano Al2O3 additive-enhanced the deposition of Ni-P on AZ91 magnesium composite and hereafter the similar consequences are detected just in case of SiO accumulation. Effect of ZnO was also noticed. So is extremely clear that Ni-P coating is extremely effective to scale back the corrosion and rise the wear and tear behaviour if it's used together with Nano additive and therefore the surfactants.

Microstructural analysis has been performed on magnesium alloy electrodes, the material used for saltwater lantern batteries. This research aims to obtain detailed and accurate information needed to support the analysis of magnesium alloy corrosion resistance caused by the electrolysis process using various analytical methods in SEM(Scanning Electron Microscopy). It is a tool that uses an electron beam to display the surface structure and composition of a test material. The test carried out on this magnesium alloy electrode is to crush the electrode into a fine powder. Then the powder is put into a container for SEM-EDS testing. Magnifications start from 1,000xuntil 15,000x. The results showed that the greater the magnification on the microscope, the more it was seen that the lumps looked brittle. Then on the surface of the magnesium alloy electrodes, 58.00 wt% magnesium material is contained.

This research explored the corrosion effect of NaCl solution on the surface quality of AZ31 magnesium alloy. Cubic-shaped specimens were immersed in standard 3.5% NaCl solution for 1, 2, 3, and 4 hours. The size of corrosion pits, fatigue crack propagation area, and surface topology were characterized. Fatigue tests were carried out on pre-corroded AZ31 specimens under different stress amplitudes. The correlation between the corrosion time and the virtual crack size was obtained. The virtual crack size is a new parameter that can relate the corrosion to the fatigue life. A new model was proposed to map the surface topology on the virtual crack size of pre-corroded AZ31 magnesium alloy. The fatigue life of 1-4-hour pre-corroded AZ31 specimens could be predicted accurately by this new model. The Levenberg-Marquardt and curve-fitting methods were used to obtain the constant parameters. The relative error between the crack size corresponding to the immersion time and the virtual crack size calculated by the proposed model was less than 1%.

The purpose of this study is to observe the change in the microstructure of the magnesium AZ91 alloy with the help of refinement of the grain structure due to Friction Stir Processing (FSP), result...

Ni–B and Montmorillonite (MMT)-containing Ni–B deposits were electrolessly plated on AM60B magnesium alloy. The Ni–B coating showed cauliflower-like micromorphology, microcrystalline-amorphous micr...

The roles of Al11Sm3 and Al2Sm phases on microstructure evolution, mechanical properties and corrosion behavior of the Mg-5Sm-xAl system was investigated. The results showed that adding Al to Mg–5Sm binary alloy brought two Al–Sm phases, Al11Sm3 and Al2Sm, which had two distinct roles regarding the microstructure evolution, mechanical properties and corrosion behavior of the Mg-Sm-Al alloy. Al11Sm3 produced a strong galvanic couple with the Mg matrix, and significantly accelerated the corrosion. The Al2Sm particles promoted heterogeneous nucleation and refined the grains, which increased the tensile strength and ductility. Both types of Al–Sm particles provided strengthening effect for the alloy. With higher Al contents, Al2Sm formed an Al oxide protective surface layer and increased corrosion resistance.

In recent years, magnesium-based materials have become expected to replace conventional engineering plastics as next-generation industrial materials to protect the global environment. However, in the production technology, problems of cracking and unstable accuracy in drilled hole shapes persist in plastic molding and machine tool processing; many studies have been conducted to address these problems. In dry machining ignition can be caused by the material, so wet machining is the prevalent method. However, it is necessary to establish a machining method with improved environmental parameters, considering the impact of oil mist and waste oil treatment on woks. In this study, the relationship between machining temperature and the accuracy of hole shapes in magnesium alloy AZ31 is investigated with four types of drills: high-speed steel, cemented carbide (K-Base), diamond-like carbon (DLC; K-Base), and TiN-coated cemented carbide (K-Base). The drill tip angle is set to 116°, 118°, or 120°. The work material used is the extruded AZ31 magnesium alloy. To evaluate the hole shape accuracy, squares of 80 × 80 mm are used. The cutting temperature is measured over an area of 12 × 30 mm. The work material is drilled using a dry method with a 3-mm-diameter drill having the aspect ratio (L/D) of 10. The tool protrusion length of 50 mm and cutting speed of 20 m/min are fixed, and the tool feed rate and drill step amount are changed. The experiment is repeated 3 times. The burr generated around the loophole on the back surface of the test material after the test is evaluated with a criterion burr height H of 0.02 mm. Furthermore, the average roughness (Ra) of the centerline is measured on the inner surface of the hole with a contact-type roughness meter. The results show that when using the three drill point angles of 116°, 118°, and 120° in the drill step, no burrs form at the exit of the drill hole. Carbide tools form burrs when the feed rate exceeds 30 mm/min and the step amount exceeds 20 mm. TiN tools are highly accurate up to a tip angle of 118°, while DLC tools have lower cutting forces and yield better finished surfaces than the other tools.

Thanks to its excellent mechanical properties, magnesium alloys have many potential applications in the aerospace and other fields. However, failure to adequately solve corrosion problems of magnesium alloy becomes one of the factors restricting its wide use in many industrial fields. Inspired by nature, researchers designed and fabricated bio-inspired water-repellent (superhydrophobic and slippery liquid-infused porous surface) surfaces with special wetting properties by exploring the surface microstructures of plants and animals such as lotus leaf and nepenthes pitcher, exhibiting excellent corrosion-resistant performance. This article summarizes the research progress on corrosion resistance of magnesium alloys with bio-inspired water-repellent properties in recent years. It mainly introduces the corrosion reasons, types of corrosion of magnesium alloys, and the preparation of magnesium alloys with bio-inspired water-repellent properties to improve corrosion resistance. In particular, it is widely used and effective to construct water-repellent and anti-corrosion coating on the surface of magnesium alloy by surface treatment. It is hoped that the research in this review can broaden the application range of magnesium alloys and provide a powerful reference for the future research on corrosion resistance of magnesium alloys.

The production of various housings of the units operating under the pressure of liquids or gases requires the use of alloys with increased soundness after casting. We compare the properties of the magnesium alloys most widely used for producing leakproof castings, namely, ML10, Elektron 21, EZ33A, ZE41A, and ZE63A. For each of them, the equilibrium and nonequilibrium freezing ranges, the heat of solidification, and the fraction of eutectic in a structure are calculated, and the dynamics of the change in the rate of solidification of an alloy in the freezing range is estimated. The shape and size of shrinkage cavity in castings made of the alloys are also determined, and the shrinkage porosity of the castings was measured. The causes for the low soundness of the ML10 alloy castings are considered. The contribution of the eutectic phase content and the freezing range wideness of an alloy to the formation of a soundness casting wall is shown to be decisive. The precipitation of a sufficient amount of eutectic in the cast structure of a magnesium alloy ensures high soundness even in the presence of shrinkage porosity in a casting. The best tightness among the alloys is demonstrated by the EZ33A and Elektron 21 alloys, which have a sufficient amount of eutectic and a short freezing range.

Results of a study of the structure, phase composition, and main parameters of high-temperature strength of forgings from deformed magnesium alloy VMD16 of the Mg – Zn – Zr – REE system in aged condition are presented. The distinctive features of alloy VMD16 responsible for the thermal stability and high-temperature strength of the alloy are determined, which make it superior to the commercial refractory alloy MA12. It is shown that thermally stable LPSO-phases are present in alloy VMD16 in the form of nanoplates in the bulk of grains and in the form of nanoblocks in multilayer fragments of the eutectic.

Due to their properties (low density, high corrosion resistance, easy to process), magnesium alloys are used in all important industrial fields (aeronautics, automotive, transport, etc.). Magnesium is the lightest metal for complex metal structures with a density 2-3 times lower than that of aluminum and a quarter than that of steel. The possibility of joining magnesium with other materials allows a greater flexibility in designing and increasing the number of applications for light alloys.This paper presents results obtained by ISIM Timisoara for FSW welding of magnesium alloy AZ31B. Considering the difficulties that arise when welding magnesium alloys using classical processes, it can be assumed that by applying the FSW process for joining these types of materials, the results obtained are very good and can substantiate industrial applications.

The effect of restored energy items in recrystallization simulation of AZ31 Mg alloy was studied with multi-order phase field model, and the impact factors during the recrystallization were discussed by changing the parameters of the restored energy item. The simulation results showed that the greater the restored energy, the greater the number of the recrystallized grains.

The effect of cryogenic treatment (CT) on the microstructure and mechanical properties of the as-extruded Mg–3.5Zn–0.6Gd alloy was investigated. The results showed that W-phase newly appeared in cryogenic treatment samples but without notable second phase amount increasing. There was also no remarkable grain refinement. But the amount of twins reduced greatly, the strong basal texture {0001} rotated and increased. The intensity of plane (0002) diffraction peak was weakened along with planes ( 1 0-1 0 ) ( 1 0-1 1 ) being enhanced in X-ray diffraction pattern. The change in mechanical properties was not obvious. The mechanism of the microstructure evolution is discussed as well.

Magnesium alloys are very interesting engineering materials due to their very high strength to density ratio (the best among metallic alloys). However, because of low hardness as well as low resistance against erosion, abrasion and corrosion, their applications in the industry is very limited. In order to improve mechanical performances, deposition of hardening coating by thermal spraying was proposed. In this work, the WC-based coatings with different binder (Co or Ni) and co-hardening additives (Cr or Cr3C2) manufactured by high velocity oxy-fuel (HVOF) were studied. These coatings were deposited onto AZ31 magnesium alloy. The crucial problem is obtaining good-adhered coating without damage the substrate, because of relatively low temperature resistance of magnesium alloys (about 300 °C). To solve this problem, HVOF method, which is low temperature and high velocity, was proposed. Also an important role plays process parameters (e.g. spray distance, fuel medium, type of nozzle). The goal of the study was to compare three types of cermet coatings manufactured from commercially available powders (WC-Co, WC-Co-Cr and WC-Cr3C2-Ni) in terms of their microstructure features, microhardness, instrumented indentation and fracture toughness. Results revealed that selected process parameters made it possible to obtain well-adhered coating with good fulfillment of the surface unevenness of the AZ31 substrate. The most noticeable effect was influence of cobalt matrix on higher hardness (1.4 – 1.6 GPa) and Young modulus (330 – 340 GPa) of deposited coatings in compare to the nickel matrix ones (1.2 GPa and 305 GPa, respectively). The same trend was observed in case of fracture toughness, c.a. 6.5 MPa·m1/2 for Co-matrix and 4.9 MPa·m1/2 for Ni-matrix