Properties Of Magnesium Alloy Research Articles

Effect of Some Impurities on the Structure, the Phase Composition, and the Properties of Magnesium Alloys Containing Rare-Earth Elements

The effect of a number of natural impurities (hydrogen, nitrogen, oxygen, aluminum) on the phase formation in magnesium alloys with rare-earth elements (REEs) has been studied. The most active gaseous impurity is found to be hydrogen, which forms disperse yttrium and zirconium hydrides and other phases. The compounds of the alloying components of an alloy with these impurities can slightly increase the strength properties of deformed complex Mg–Zn–Zr–REE alloys; in this case, their fatigue characteristics decrease by a factor of 1.3–1.5.

Закономерности формирования текстуры и анизотропии механических свойств магниевых сплавов

Закономерности формирования текстуры и анизотропии механических свойств магниевых сплавов

Development of magnesium alloys for biomedical applications: structure, process to property relationship

Magnesium alloys as biodegradable materials have been used in clinic for coronary stents and bone screws, however the low mechanical properties and fast degradation behaviour still limit their application, which attracted many researches to resolve them. In this review, the development of alloying and plastic deformation to control the composition and microstructure of the alloys and improve the mechanical property and degradation behaviour is introduced. Since the biocompatibility and biodegradation must be considered for the design of new biodegradable magnesium alloys, so the possibility to improve the mechanical properties is much restricted. Higher mechanical properties of magnesium alloys are expected to be reached by more attention on combination of new alloy design, heat treatment and plastic deformation techniques. The development of corrosion resistant magnesium alloys still needs much more studies including the corrosion resistant mechanisms fundamental researches.

Effect of Iron Impurity on the Phase Composition, Structure and Properties of Magnesium Alloys Containing Manganese and Aluminum

Results of a study of the interaction between iron impurity and manganese and aluminum alloying elements during formation of phase composition in alloys of the Mg – Mn, Mg – Al, Mg – Al – Mn, and Mg – Al – Zn – Mn systems are presented. It is proved that this interaction results in introduction of Fe into the intermetallic phase. The phase compositions of model magnesium alloys and commercial alloys MA2-1 and MA5 are studied. It is shown that both manganese and aluminum may bind the iron impurity into phases. Composite Fe-containing intermetallic phases of different compositions influence differently the corrosion resistance of magnesium alloys.

Effect of Si addition on microstructure and properties of magnesium alloys with high Al and Zn contents

In order to assess the possibility of using magnesium alloys with high Al and Zn contents as degradable fracturing balls, the effects of Si addition on microstructures, mechanical properties and degradable behavior of Mg-17Al-5Zn (mass.%) alloy were investigated. The results show that the minor Si addition can refine α-Mg matrix and modify Mg2Si particles. With the increase of Si content, the yield strength of the alloys initially increases and reaches to the maximum 309 MPa in alloy containing 0.5 wt % Si. The degradable corrosion rate exhibits an inverse trend and reaches the maximum in alloy containing 3 wt % Si with 0.46 mm/day at 298 K and 5.39 mm/day at 366 K, respectively.

Evaluation of Friction Properties of Magnesium Alloy during Hot Forging by Ring Compression Test

This paper deals with friction properties and deformation resistance during hot forming of Mg-Al-Ca-Mn series magnesium alloys. Friction coefficients between dies and magnesium alloys were obtained by ring compression tests that used graphite, PTFE, and an oil lubricant in a hot-forging process. Hot forging was performed under various conditions to clarify the effects of types of lubricants and slide motion of the press machines on friction properties. Two types of slide motion, a constant velocity motion and a pulse motion were selected in the ring-compression test. It was found that graphite with an oil lubricant effectively eliminated die sticking in hot forming of magnesium alloys. The isothermal deformation resistances were derived using friction coefficients obtained by ring-compression tests as well as finite-element simulations. The predicted stress strain curves with temperature were examined with the stress-strain relationship obtained in experiments using a servo press and demonstrated the effectiveness of the proposed method.

Methodology for <i>In Situ</i> Microstructural Characterisation of AZ31 Magnesium Alloy Corrosion Degradation in Hanks' Solution

Due to their specific properties magnesium and magnesium alloys find huge application possibilities mainly in automotive, engineering, transport and space industry. Important properties of magnesium alloys for engineering applications are high specific strength and high internal dumping values, while biocompatibility, biotoxicity and biodegradability open them the possibility to be used for biomedical applications. Development of new biodegradable magnesium alloys, investigation of new production and processing technologies on their properties and evaluation of corrosion degradation in simulated body fluids solutions are the main topics of the last decades.The paper offers a method simulating in-vivo tests for description of the corrosion process of potential biomedical materials in time using atomic force microscopy (AFM). To prove the proposed methodology detailed analysis of the corrosion degradation of AZ31 cast magnesium alloy in flowing Hanks’ balanced salt solution (HBSS) was performed. Corrosion degradation process of the examined alloy was influenced by different microstructural features and their interfaces. Results of the created corrosion galvanic cells and the corrosion attack evolution on the interface of the present intermetallic phases and the matrix led to profile changes detected by AFM.

Inclusions in Permanent Mold Cast Magnesium ZE41A and AZ91D Alloys

This study was part of a pioneering industry-focused AFS research project characterizing and examining the effects of inclusions in magnesium alloys during melting and casting. It seeks an improvement in the mechanical properties of magnesium alloys through a better understanding of the inclusions formed during melting and casting. These inclusions were examined by characterizing the grain size, mechanical properties, and fracture surface inclusion contents of tensile and fracture bar permanent mold castings of ZE41A and AZ91D magnesium alloys. The castings were produced near the start and the end of production runs from four different foundries. For both ZE41A and AZ91D alloy castings, the average yield strength, ultimate tensile strength, and elongation of the castings decreased between the start and end of the production run. For both alloys, an increase in grain size was observed between the start and end of the production run but the reduction in mechanical properties was mainly attributed to particle-type Mg–Al–O inclusions in the AZ91D alloy and film-type Mg–O inclusions in the ZE41A alloy on the fracture surfaces of the tensile samples and fracture bars. The AZ91D castings had very few inclusions, but these inclusions were much larger than those in the ZE41A castings. This research recognized extensive variability of the inclusion levels in the industry and is a precursor to developing industry standards for melt cleanliness in Mg alloys. This will be a major step in enabling improved quality and enhanced use of magnesium alloys in aerospace and automotive industries.

Effect of twin boundary segregation on damping properties in magnesium alloy

The effect of solute segregation at deformation twin boundaries on the strength (hardness) and damping capacity was investigated using an extruded Mg-Y binary alloy. The existence of deformation twin brought about an increase in both the hardness and the damping capacity. However, a subsequent annealing had a different effect, in which segregation at twin boundaries led to a decrease in the damping capacity. This is because the segregation of yttrium stabilized the twin boundaries; as a result, these boundaries inhibited alternate shrinkage and growth of deformation twin, by which the vibration energy is absorbed.

Achieving superplastic properties in a ZK10 magnesium alloy processed by equal-channel angular pressing

Equal-channel angular pressing provides an opportunity for refining the grain structure and introducing superplastic properties in magnesium alloys. This report describes the use of this processing technique with a ZK10 (Mg–1.0wt.% Zn–0.26wt.% Zr) alloy. The grain structure was successfully refined from ∼12.9 to ∼5.2μm after 4 passes and superplastic elongations were observed when testing at low strain rates at temperatures of 473 and 523K. An analysis shows that the superplastic behavior is consistent with the conventional theoretical model for superplastic flow and at higher stresses and strain rates there is a transition to control by a viscous glide process.

Effect of the Porosity Ran ge and its Nature on Mechanical Properties of Magnesium Alloys Mg-Al-Zn

The possibilities of porosity adjustment in alloys of the Mg-Al-Zn system obtained by melting under a layer of flux were studied. The elements that significantly increase corrosion resistance and heat resistance, and improve mechanical strength and technological characteristics were chosen as doping components. Measurements showed that the range of porosity varied between 5.9 and 14.8%, and the relationship<br />between porosity and strength of alloys was defined for the first time for this range. For an alloy with porosity of 14.8%, the percentage of open pores was 12.8% while the percentage of closed pores was 2%. Micro-hardness of alloys with the given porosity was 661 MPa after casting, 876 MPa after homogenizing annealing and 897 MPa after artificial aging. The tensile strength was 235 MPa. Analysis identified that the main cause of porosity was catching atoms of hydrogen from atmosphere by molten alloys during melting, casting and liquation. In order to reduce the percentage of porosity alloys were doped by metal manganese, liquid metal was processed by calcium and hexachloroethane, and casting form was treated by boron nitride. These manipulations resulted in reduction of samples porosity up to 5.9%, increase of tensile strength up to 240 MPa. Open porosity was 4.5%, while closed porosity was 1.4%. At the same time micro-hardness of cast samples was 867 MPa, 903 MPa after homogenization annealing and 961 MPa after artificial aging. Further reduction of porosity and increasing of magnesium alloys strength is possible with the use of inert gases or vacuum melting. Samples porosity can be increased by more than 14.8% with the help of melting in the hydrogen containing atmosphere.

Effect of different c/a ratio on the microstructure and mechanical properties in magnesium alloys processed by ECAP

Three magnesium alloys, AE21, AE42 and LAE442, were prepared by ECAP employing 1–12 passes. The microstructure evolution during ECAP was systematically analyzed by EBSD. The AE21 and AE42 alloys show typical texture after ECAP with grains predominantly oriented with basal planes inclined by ∼55° from processing direction. This texture results from activation of basal slip during ECAP following the route BC. The LAE442 alloy showed different texture formation, which is fully explained by different c/a ratio and activation of non-basal slip. The differences in the microstructure evolution resulted in different performance in mechanical loading. In the present study a complex investigation of mechanical properties is performed using uni-axial tensile and compression deformation tests and also by Vickers indentation that simulates multi-axial deformation. Resulting microhardness evolution was therefore correlated to grain size according to Hall–Petch relation and to the evolution of dislocation density measured by positron annihilation spectroscopy. On the other hand, the yield stress in the tensile and compression uni-axial deformation tests was determined mainly by the texture. It was shown that by tailoring the c/a ratio the typical texture development could be effectively suppressed in magnesium alloys processed by ECAP and in such way the negative effect of texture on strength can be avoided.

マグネシウム合金箔の創製とその特性

マグネシウム合金箔の創製とその特性

Determination of Mechanical Properties of Magnesium Alloys and Composites by Small Punch Testing

Tests on miniature samples are increasingly used for the determination of mechanical properties of materials available in small volumes (non-destructive or semi-destructive approach). Small punch testing at constant deflection rate (SPT-CDR) of selected magnesium alloys and composites was performed at room temperature. Mechanical properties (yield strength, ultimate strength) were evaluated from SPT and correlated with results of uniaxial tensile tests (UTT). SPT characteristics were converted to uniaxial tensile properties by empirical formulas available in the literature. New formulas more appropriate for magnesium alloys were suggested.

Effects of Sn addition forms on microstructure and mechanical properties of AZ31 magnesium alloy

In the present paper, the influences of the addition forms of Sn, such as nanoparticles or ingot, on the microstructure and properties of magnesium alloy matrix were investigated. It was found that the size of as-formed Mg2Sn phases was in nano scale for the sample with Sn nanoparticles addition. While Mg2Sn phases were in macro scale for the sample with Sn ingot addition. The strength and plasticity of the AZ31 alloy matrix were improved because of the Sn additions regardless of nanoparticle or ingot. However, the AZ31 alloy with Sn ingot addition exhibited better mechanical properties than the sample with the nanoparticle addition, which could be owing to the loss of Sn nanoparticles in the processing of smelting and existence of nanoscopic Mg2Sn phase as particle clusters in the matrix.

Effect of hot working on the damping capacity and mechanical properties of AZ31 magnesium alloy

Magnesium alloys have received much attention for their lightweight and other excellent properties, such as low density, high specific strength, and good castability, for use in several industrial and commercial applications. However, both magnesium and its alloys show limited room-temperature formability owing to the limited number of slip systems associated with their hexagonal close-packed crystal structure. It is well known that crystallographic texture plays an important role in both plastic deformation and macroscopic anisotropy of magnesium alloys. Many authors have concentrated on improving the room- temperature formability of Mg alloys. However, despite having a lot of excellent properties in magnesium alloy, the study for various properties of magnesium alloy have not been clarified enough yet.Mg alloys are known to have a good damping capacity compared to other known metals and their alloys. Also, the damping properties of metals are generally recognized to be dependent on microstructural factors such as grain size and texture. However, there are very few studies on the relationship between the damping capacity and texture of Magnesium alloys. Therefore, in this study, specimens of the AZ31 magnesium alloy, were processed by hot working, and their texture and damping property investigated. A 60 mm × 60 mm × 40 mm rectangular plate was cut out by machining an ingot of AZ31 magnesium alloy (Mg-3Al-1Zn in mass%), and rolling was carried out at 673 K to a rolling reduction of 30%. Then, heat treatment was carried out at temperatures in the range of 573-723 K for durations in the range of 30-180 min. The samples were immediately quenched in oil after heat treatment to prevent any change in the microstructure. Texture was evaluated on the compression planes by the Schulz reflection method using nickel-filtered Cu Kα radiation. Electron backscatter diffraction measurements were conducted to observe the spatial distribution of various orientations. Specimens for damping capacity measurements were machined from the rolled specimen, to have a length of 120 mm, width of 20 mm, and thickness of 1 mm. The damping capacity was measured with a flexural internal friction measurement machine at room temperature. It was found that the damping capacity increases with both increasing heat-treatment temperature and time, due to grain growth and the increased pole densities of textures.

Review the Effect of Welding Processes on the Comprehensive Mechanical Properties of Magnesium Alloy Joints

In this paper, the effect of welding processes such as friction stir welding (FSW), laser beam welding (LBW) and pulsed current gas tungsten arc welding (PCGTAW) on comprehensive mechanical properties of AZ31B magnesium alloy was reviewed. Among the three different welding processes, the LBW joints showed superior comprehensive properties to FSW and PCGTAW joints. The formation of very fine grains in weld region, higher fusion zone hardness, uniformly distributed finer precipitates were the main reasons for superior comprehensive mechanical performance of LBW joints compared to PCGTAW and FSW joints.

Effect of alloying elements on the texture and the anisotropy of the mechanical properties of magnesium alloys with REM, lithium, and aluminum

The formation of the texture and the anisotropy of the mechanical properties in extruded rods of commercial alloys MA5, MA18, MA21 and also experimental Mg-Y-based and Mg-Y-Ce-based alloys are studied by X-ray diffraction and the measurement of the hardness and the tensile and compressive properties. It is shown that the magnesium alloys can be separated into three groups according to the anisotropy of the mechanical properties. The first group consists of the alloys not containing rare-earth metals and lithium, and the second group is the alloys with yttrium for which the yield strength in the axial direction of the rods are significantly higher than those in the transverse direction. The alloys of the first group demonstrate a substantial excess of the yield strength in the axial direction in the tension tests as compared to those in compression tests, and the second group alloys do not demonstrate such a difference. The ceriumand lithium-containing alloys (the third group) exhibit a weak anisotropy of the strength properties. A method for estimating the anisotropy of the strength properties is developed on the basis of calculation of the Taylor factors for basal slip averaged over all orientations of crystallites, and a quantitative method is developed for determining the phase composition by measuring the solid solution lattice parameter.

Semisolid Processing of Magnesium Alloys: Microstructure - Property Relationship

An application of semisolid processing to magnesium alloys is discussed emphasizing both the fundamental and applied research activities aimed at better understanding the microstructure-property relationship. The reduced temperature of semisolid processing, providing common benefits of longer tool life, tighter dimensional tolerances and better process consistency is of special importance for magnesium alloys due to their high affinity to oxygen, requiring an expensive protection and leading otherwise to ignition and burning. However, the reduced temperature resulting in higher part integrity does not create beneficial microstructural characteristics converting to substantially improved mechanical properties. Major microstructural factors controlling properties of magnesium alloys after semisolid processing are discussed.

Research on the Mechanical Properties and Corrosion Resistance of Mg-RE and Mg-Zn-Cu Alloys

Rare earth magnesium alloys and Mg-Zn-Cu alloys were prepared by gravity casting and direct squeezing casting respectively, and the corrosion performances of three kinds of Mg-Zn-Cu alloys were compared in this paper. The results indicate that adding rare earth elements and direct squeezing casting process can significantly increase the mechanical properties of magnesium alloys, and aluminum can improve the corrosion resistance of magnesium alloys.