Properties Of AZ31 Magnesium Alloy Research Articles

Microstructural Evolution and Mechanical Properties of AZ31 Magnesium Alloy Processed through Constrained Groove Pressing at Different Deformations and Temperatures

Microstructural Evolution and Mechanical Properties of AZ31 Magnesium Alloy Processed through Constrained Groove Pressing at Different Deformations and Temperatures

Effect of Zinc and Severe Plastic Deformation on Mechanical Properties of AZ61 Magnesium Alloy.

This study investigates the effects of zinc (4 wt.%) and severe plastic deformation on the mechanical properties of AZ61 magnesium alloy through the stir-casting process. Severe plastic deformation (Equal Channel Angular Pressing (ECAP)) has been performed followed by T4 heat treatment. The microstructural examinations revealed that the addition of 4 wt.% Zn enhances the uniform distribution of β-phase, contributing to a more uniformly corroded surface in corrosive environments. Additionally, dynamic recrystallization (DRX) significantly reduces the grain size of as-cast alloys after undergoing ECAP. The attained mechanical properties demonstrate that after a single ECAP pass, AZ61 + 4 wt.% Zn alloy exhibits the highest yield strength (YS), ultimate compression strength (UCS), and hardness. This research highlights the promising potential of AZ61 + 4 wt.% Zn alloy for enhanced mechanical and corrosion-resistant properties, offering valuable insights for applications in diverse engineering fields.

STUDY ON EPOXY RESIN/MULTI-WALLED CARBON NANOTUBES CONDUCTIVE COATING ON AZ31 MAGNESIUM ALLOY AFTER MICRO-ARC OXIDATION

After micro-arc oxidation, the surface properties of AZ31 magnesium alloy have been improved. However, micro-arc oxidation treatment leads to high insulation, which limits its application in electronic devices. To increase conductivity, a conductive coating was developed by adding multi-walled carbon nanotubes (MWCNTs) to the epoxy resin. The microstructure and performance of the coating were tested by SEM, thermogravimetric analyzer, four-probe conductivity meter, high-temperature friction and wear tester, and electrochemical workstation. The results indicate that the optimal conductivity with a resistivity of 303[Formula: see text][Formula: see text]m is obtained when the MWCNT content is at 4[Formula: see text]wt%. In addition, MWCNTs are filled with a network structure of epoxy resin, which increases the density of the coating and enhances their wear and corrosion resistance.

Grain refinement and strengthening mechanism of AZ31 magnesium alloy formed by pre-upsetting alternating forward extrusion

The pre-upsetting deformation process was added before the alternating forward extrusion forming, which can significantly refine the grains and improve the mechanical properties while reducing the load. The effects of 14%, 25%, 36% pre-upsetting deformation on the microstructure and mechanical properties of AZ31 magnesium alloy were investigated. The results show that the pre-upsetting alternating forward extrusion (UAFE) process can achieve significant grain refinement from 31.1 µm to 2.9–3.5 µm. With the increase of pre-upsetting deformation, the elongation at break tends to decrease and the tensile strength tends to increase. The comprehensive mechanical properties of U2AFE are the best, the yield strength and tensile strength are 203.1 MPa and 299.0 MPa respectively, and the elongation at break is 12.5%. The enhancement of the pre-upsetting deformation process not only makes the basal plane of grains in the billet randomly distributed and weakens the basal plane texture, but also stores a large amount of strain energy and dislocation inside the billet, which accelerates the subsequent continuous dynamic recrystallization (CDRX) process of alternating extrusion. This provides scientific guidance and technical support for the research of high-performance magnesium alloy extrusion forming technology.

Enhanced mechanical properties of AZ91 magnesium alloy by asynchronously large-strain high-efficiency rolling with bimodal grain structure

The study describes large strain high-speed asynchronous rolling process to process AZ91 magnesium alloy sheets with an overall thickness reduction of 84 % via two-pass rolling at 350 °C. Rolling speed ratios of 1.0, 1.1, 1.2, and 1.3 were used to obtain bimodal grain structure with different organizational states. Microstructural analysis unraveled that the formation of the bimodal structure was a consequence of combined effect of precipitation-strengthening and the Zener pinning effect. The R3 exhibiting an asynchronous ratio of 1.2 exhibited an optimized bimodal grain structure characterized by smaller recrystallized grains and a more homogeneous distribution. This phenomenon underscored the beneficial impact on enhancing strength and alleviating the anisotropic behavior.

Recrystallization and Anisotropy of AZ31 Magnesium Alloy by Asynchronous Rolling

In this study, the microstructure and mechanical properties of AZ31 magnesium alloy were investigated through asynchronous rolling. The results demonstrate that the rolled sample exhibits a refined grain structure with a significant presence of continuous dynamic recrystallization. Notably, as the roll speed ratio increases, the grain refinement becomes more apparent. For the sample with a roll speed ratio of 1.3, the tensile strength in the rolling direction (RD) reaches 273 MPa, while the elongation measures 20.2%. Similarly, in the transverse direction (TD), the tensile strength reaches 282 MPa, accompanied by an elongation of 18.9%. These values indicate a substantial improvement in elongation compared to conventional rolling processes. The enhanced elongation can be attributed to two primary factors. Firstly, recrystallization contributes to a grain refinement recrystallization ratio of 86%, promoting improved mechanical properties. Secondly, the recrystallized grains induce a favorable Schmidt factor, further supporting elongation. Overall, the findings of this research highlight the benefits of asynchronous rolling in refining the microstructure and enhancing the mechanical properties of AZ31 magnesium alloy.

Deformation localization behavior research of AZ31 magnesium alloy under impact load

The dynamic mechanical properties of AZ31 magnesium alloys were analyzed under different strain rates by using a separated Hopkinson pressure bar system. The microstructure of the specimens was observed by optical microscopy. The results show that the dynamic yield strength of AZ31 magnesium alloy is insensitive to the strain rate. The compressive strength is increasing and shear deformation localization behavior is more obvious with the increase in the strain rate. Meanwhile, the temperature within the shear band is about 241 k and meets the twinning dynamic recrystallization temperature. Temperature rise promotes the grain refining effect.

Modeling the correlation between texture characteristics and tensile properties of AZ31 magnesium alloy based on the artificial neural networks

This work is aimed to investigate the relationship between the texture and tensile properties of the AZ31 Mg alloy by the machine learning method. The texture characteristics parameters, namely the maximum pole intensity (Imax), texture dispersion (D), and texture directivities along the longitudinal direction (PLD) and transverse direction (PTD), are extracted from the (0002) pole figures of the AZ31 Mg alloy. An artificial neural networks (ANN) model to describe the relationship between the texture characteristic parameters and tensile properties is constructed and trained by the data collected from the literature. To validate the reliability and generalization performance of the ANN, 6 samples with different texture characteristics are prepared, and their textures and tensile properties are evaluated through electron backscattered diffraction (EBSD) measurement and uniaxial tensile test, respectively. The results indicate that the ANN model exhibits good prediction performance in yield strength and elongation of the AZ31 Mg alloy when it is applied to the new cases. The correlations between the texture characteristics and tensile properties are analyzed according to the ANN-predicted results. The maximum pole intensity and texture dispersion significantly influence the tensile properties of the AZ31 Mg alloy. With increasing the Imax or decreasing the D, the strength is increased but the elongation is reduced. As increasing the texture directivity along the LD, the tensile properties of the AZ31 Mg alloy show non-monotonic changes. This research presents a correlation model between the texture and mechanical properties of the Mg alloy, which contributes to the development of high-performance Mg alloys.

Microstructure and mechanical properties of AZ91 magnesium alloy fabricated by multi-layer and multi-pass CMT based WAAM technique

The block sample of AZ91 magnesium alloy was fabricated via multi-layer and multi-pass wire and arc additive manufacturing (WAAM) based on cold metal transfer (CMT) technique, and the dimension of the sample could better meet the requirement of actual production compared with the thin-walled sample prepared by the multi-layer and single-pass process. The sample was composed of equiaxed grains. The grain size was homogeneous in the deposited passes, while there was an obvious difference of grain size in the junction area of the deposited passes. The average tensile strength and elongation of the sample in the traveling direction were 246.7 MPa and 19.4%, respectively, while those in the pass overlap direction perpendicular to the traveling direction were 127.1 MPa and 11.6%, respectively, due to the formation of defects and brittle second phases.

Effect of Plasma Argon Pretreatment on the Surface Properties of AZ31 Magnesium Alloy

Climate change has evidenced the need to reduce carbon dioxide emissions into the atmosphere, and so for transport applications, lighter weight alloys have been studied, such as magnesium alloys. However, they are susceptible to corrosion; therefore, surface treatments have been extensively studied. In this work, the influence of argon plasma pretreatment on the surface properties of an AZ31 magnesium alloy focus on the enhancement of the reactivity of the surface, which was examined by surface analysis techniques, electrochemical techniques, and gravimetric measurements. The samples were polished and exposed to argon plasma for two minutes in order to activate the surface. Contact angle measurements revealed higher surface energy after applying the pretreatment, and atomic force microscopy showed a roughness increase, while X-Ray photoelectron spectroscopy showed a chemical change on the surface, where after pretreatment the oxygen species increased. Electrochemical measurements showed that surface pretreatment does not affect the corrosion mechanism of the alloy, while electrochemical impedance spectroscopy reveals an increase in the original thickness of the surface film. This increase is likely associated with the high reactivity that the plasma pretreatment confers to the surface of the AZ31 alloy, affecting the extent of oxide formation and, consequently, the increase in its protection capacity. The weight loss measurements support the effect of the plasma pretreatment on the oxide thickness since the corrosion rate of the pretreated AZ31 specimens was lower than that of those that did not receive the surface pretreatment.

Effect of multi-pass continuous screw twist extrusion process on microstructure evolution, texture, and mechanical properties of AZ31 magnesium alloy

Effect of multi-pass continuous screw twist extrusion process on microstructure evolution, texture, and mechanical properties of AZ31 magnesium alloy

Effect of Squeeze Casting and Combined Addition of Calcium and Strontium on Microstructure and Mechanical Properties of AZ91 Magnesium Alloy

Effect of Squeeze Casting and Combined Addition of Calcium and Strontium on Microstructure and Mechanical Properties of AZ91 Magnesium Alloy

Microstructure and properties of Nb2O5/Mg gradient coating on AZ31 magnesium alloy by magnetron sputtering

A Nb 2 O 5 /Mg gradient coating was synthesized on AZ31 magnesium alloy through the magnetron sputtering technique. The microstructure and properties of the coating were investigated by SEM, AFM, EDS and XPS, scratch tester, nanoindenter, friction tester, and electrochemical workstation, with a Nb 2 O 5 monolayer coating as a control. The results show that all the as-disposed films have an amorphous columnar structure, and can improve the mechanical, anti-wear and anti-corrosion properties of AZ31 magnesium alloy. The Nb 2 O 5 /Mg gradient coating shows a gradual change in chemical composition through its depth, decreasing the residual stress of the coating/substrate system, thus reducing the risk of film cracking, and increasing compactness of the coating. Compared with a Nb 2 O 5 single-layer film of the same thickness, the gradient coating exhibits increased adhesion, H/E and H 3 /E 2 increased by about 16 times, 7.8% and 100% respectively, and a wear rate reduced by more than an order of magnitude. In addition, the gradient coating has better corrosion resistance, having a two orders of magnitude lower current density and one order of magnitude higher polarization resistance. This study provides a workable strategy for improving the performance of ceramic coatings on magnesium alloy, for medical applications. • Nb 2 O 5 /Mg gradient coating was applied to AZ31 magnesium alloy using magnetron sputtering. • The gradient coating is compact, without cracks. • The gradient coating show higher adhesive, mechanical, and anti-corrosion properties than the monolayer coating.

Microstructure and mechanical properties of AZ31 magnesium alloy prepared using wire arc additive manufacturing

AZ31 magnesium alloy structural parts were formed using the wire arc additive manufacturing technology (WAAM), and the microstructure and mechanical properties of the additive–substrate interface bonding zone and the additive zone were studied. Due to the repeated heating under the heat source during the additive manufacturing process, the longitudinal section of the additive zone had obvious non-uniform features. The grain size of the longitudinal section of the additive zone increased from 4.27 µm to 9.51 µm from the bottom zone to the top zone. The average fraction of "hard" grains in cross section was higher than that in longitudinal section, indicating that the cross section showed less plastic strain accumulation, resulting in lower plastic than the longitudinal section. The mechanical property anisotropy of the cross section was stronger because of its higher fiber texture strength. At the same time, the longitudinal section microhardness of the additive zone increased from 74.22 HV to 81.46 HV from the top zone to the bottom zone. The tensile strength of the WAAM AZ31 magnesium alloy in the vertical direction was 286.47 MPa, and its elongation rate was 15.89 %, which was considerably greater than the ultimate tensile strength of the cast and the extruded AZ31 magnesium alloy.

Effects of arc oscillation on microstructure and mechanical properties of AZ31 magnesium alloy prepared by CMT wire-arc directed energy deposition

Cold metal transfer (CMT) arc with varied arc oscillation patterns was used to fabricate thin-wall AZ31 magnesium alloy components. The microstructure characteristics and mechanical properties of wire-arc directed energy deposition (DED) AZ31 magnesium alloy samples with or without arc oscillations were investigated experimentally. The samples were prepared by two oscillation modes, spiral oscillation and asymmetric trapezoidal oscillation, and compared with the samples without arc oscillation. Finer equiaxed grains were observed in the samples with arc oscillations and the stirring action of arc oscillation might result in the grain refinement. No visible anisotropy was found in microstructure and mechanical property in the AZ31 magnesium alloy samples with arc oscillations, and its mechanical characteristics were similar to the as-forged AZ31 alloy. As compared to the samples without arc oscillation, the yield strength and ultimate tensile strength of the arc oscillation sample increased from 70 to 90 MPa and from 196 to 233 MPa. In addition, the improvement mechanism of wire-arc DED components was discussed through the influence of arc oscillation on CMT wire-arc DED melt flow.

Effect of La/Nd ratio on precipitation kinetics and tensile properties of squeeze-cast Mg-Al-Zn-La-Nd alloys

The current study investigated the effect of adding La and Nd on the precipitation kinetics and tensile properties of AZ91 magnesium alloy. Mg-Al-Zn-La-Nd alloys with different W La /W Nd ratios were developed by squeeze casting. Typical characterization was conducted using optical microscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy to analyze the effect of W La /W Nd on the aging behavior of Mg-Al-Zn-La-Nd alloys. Thermal analysis, Vickers hardness and tensile properties were measured using the differential scanning calorimetry, optical hardness tester and universal testing machine. The results show that the addition of RE increases the diffusion resistance of Al atoms in the matrix and increases the time interval to peak aging. The precipitation activation energy and tensile properties of Mg-Al-Zn-La-Nd alloys increase with the increase of W La /W Nd . The optimal tensile properties are obtained in the alloy with a W La /W Nd of 3/2. The co-addition of La and Nd increases the precipitation activation energy and atom diffusion resistance of the AZ91 alloy. The precipitation behavior of AZ91 alloy with the addition of rare earth elements is slower than that of AZ91 alloy.

On the structure, mechanical behavior, and deformation mechanism of AZ91 magnesium alloy processed by symmetric and asymmetric rolling

In this study, the microstructural evolution, texture, and mechanical properties of AZ91 magnesium alloy rolled by symmetric and asymmetric rolling with 14%, 24% reduction, is presented. The study indicated that at identical deformation, the strength of the asymmetric rolled alloy was slightly greater than the symmetric rolled alloy, and the elongation was greatly enhanced because of finer grain size and weak {0001}//ND basal texture. The properties of the transverse direction (TD) samples are better than that in the rolling direction (RD), which is attributed to the TD samples having a {1¯1¯20}//TD texture. The TD sample by asymmetric rolled with a reduction of 24% had excellent mechanical properties with strength and elongation of 413 MPa and 5.08%, respectively, due to its fully recrystallized grains, the increase of {112¯3}//ND texture and favorable Schmid factor.

Tribological behaviour of AZ31 magnesium alloy reinforced by bimodal size B4C after precipitation hardening

Abstract This study investigated dry sliding wear properties of AZ31 magnesium alloy and B4C-reinforced AZ31 composites containing 5, 10, and 20 wt.% B4C with bimodal sizes under different loadings (10–80 N) at various sliding speeds (0.1–1 m/s) via the pin-on-disc configuration. Microhardness evaluations showed that when the distribution of B4C particles was uniform the hardness of the composites increased by enhancing the reinforcement content. The unreinforced alloy and the composite samples were examined to determine the wear mechanism maps and identify the dominant wear mechanisms in each wear condition and reinforcement content. For this purpose, wear rates and friction coefficients were recorded during the wear tests and worn surfaces were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry analyses. The determined wear mechanisms were abrasion, oxidation, delamination, adhesion, and plastic deformation as a result of thermal softening and melting. The wear evaluations revealed that the composites containing 5 and 10 wt.% B4C had a significantly higher wear resistance in all the conditions. However, 20 wt.% B4C/AZ31 composite had a lower resistance at high sliding speeds (0.5–1 m/s) and high loadings (40–80 N) in comparison with the unreinforced alloy. The highest wear resistance was obtained at high sliding speeds and low loadings with the domination of oxidative wear.

Influence of Heat Treatment on Microstructure and Mechanical Properties of AZ61 Magnesium Alloy Prepared by Selective Laser Melting (SLM).

From previous studies, it is known that the dissolution of β-Mg17Al12 at high temperature and the increase of densities at high pressure after hot isostatic pressing (HIP) are the two main reasons for significant improvement in the ductility of AZ61 magnesium alloy prepared by SLM. However, the mechanism of dissolution of β-Mg17Al12 in SLMed AZ61 magnesium alloy at high temperature is not clear. To illustrate the mechanism of the effect of β-Mg17Al12 dissolution on the ductility of SLMed AZ61 Mg alloy, the effect of solid solution heat treatment (T4) on the microstructure and mechanical properties of SLMed AZ61 was investigated and the kinetic model of β-Mg17Al12 dissolution of SLMed AZ61 magnesium alloy was established. According to the results, there is no significant change in the dissolution of the β-Mg17Al12 with an increase of temperature and time when the T4 temperature is lower than 410 °C. At the optimum solution heat treatment temperature of 410 °C, the dissolution rate is accelerated and the β-Mg17Al12 is completely dissolved after 2 h. In addition, the dissolution rate of β-Mg17Al12 decreases with the increase of dissolution time. The strength of SLMed AZ61 magnesium alloy decreases and the ductility increases as the T4 temperature increases. The strength of the specimens is reduced by grain coarsening (29.2 ± 3.7 μm), but the elongation is increased by 90% compared to SLMed AZ61, due to the effect of β-Mg17Al12 dissolution.

EFFECT OF INITIAL TEMPERATURE ON THE MICROSTRUCTURE AND PROPERTIES OF CRYOGENIC ROLLED AZ31 MAGNESIUM ALLOY

By characterizing the properties of a twin cast-rolled AZ31 sheet after cryogenic rolling, the effects of the initial temperature on the microstructure and mechanical properties of the sheet obtained by cryogenic rolling were studied. The results indicate that the hardness of the alloy was a maximum due to the high-density dislocations in the microstructure when the initial temperature was room temperature. The highest yield strength and elongation appeared at the initial temperature of 200 °C, and the microstructure was mainly fine equiaxed grains. It was observed that fine grains increased, and the yield strength and elongation gradually decreased with the increase of the initial temperature. The overall trend of yield strength and elongation increased first and then decreased. Based on the results of different initial temperature treatments, the optimal microstructure and properties of AZ31 magnesium alloy were acquired when the initial temperature was 200 °C.