Properties Of AZ31 Mg Alloy Research Articles

Application of friction stir surface treatment for modification of peripheral coarse grain structure and mechanical properties of AZ31 Mg alloy

The presence of peripheral coarse grains (PCG) in the microstructure of extruded products is considered one of the causes of decreased mechanical properties. Such microstructure has been observed at the periphery of extruded AZ31 Mg alloy. This research aims to achieve a refined and homogeneous microstructure at the structure of extruded bars of AZ31 alloy using pinless friction stir processing (FSP). Up to six passes of FSP using pinless tools with different shoulder surface geometries were conducted. Tools with varying diameters of 12, 15, and 22 mm were used to investigate the effect of shoulder geometry. The rotational speed and traverse speed of the tool were set at 900 rpm and 70 mm/min, respectively. The tool tilt angle was also set to 3°. The effect of the tool geometry on the metallurgical and mechanical properties was investigated using metallography tests, microhardness testing, tensile testing, and fracture testing. According to the results, it was found that reducing the diameter of the tool and using featured tool can lead to homogenization and reduction of the average grain size in the processed samples, increasing the microhardness compared to the primary sample. It was also observed that mechanical properties were improved with the increase in the tool diameter due to the improved quality of the processing area. For samples processed with a 22 mm diameter tool, the final strength reached 242.7 and 248.81 MPa, respectively, for the simple and featured tools.

Deformation behaviour, microstructure evolution and dynamic recrystallization mechanism of AZ31 magnesium alloy under co-extruded by Mg-Al composite billet

Conventional methods for hot extrusion of magnesium (Mg) alloy sheets have limitations for microstructure improvement and mechanical property enhancement. Co-extrusion of Mg alloy with an Al alloy core provides an opportunity for refining the grain size and improving basal texture. This study introduces a novel severe plastic deformation (SPD) method, Direct Extrusion-Continuous Shear (DE-CS), utilizing 6063 Al alloy as the core to fabricate innovative Mg/Al clad composite sheets. Monolithic Mg sheets (non-co-extruded condition) are extruded under identical conditions for comparison. By evaluating the microstructure and mechanical properties of AZ31 Mg alloy under co-extrusion and non-co-extrusion conditions, the positive effect of Mg-Al composite billet co-extrusion on AZ31 Mg alloy is established. The grain refinement effect in co-extruded samples is superior, enhancing plasticity without significant reduction in tensile strength. The microstructure evolution and dynamic recrystallization (DRX) behaviour of AZ31 Mg alloy during co-extrusion were analyzed comprehensively. The results indicate that, in the initial stages of deformation, various variants of {10−12} extension twins (ETs) play a crucial role in refining the original grains, forming initial [10−10]//ED fiber texture components alongside other non-basal components. Upon entering the shear deformation (SD) zone, deformed twins disappear, and small dynamically recrystallized (DRXed) grains emerge along boundaries of coarse deformation grains and within the grains. Strong shear deformations and compressive stress from transverse direction (TD) induce intensified prismatic <a> and pyramidal <c+a> slip, promoting continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX). CDRX predominantly affects elongated deformed grains, forming an [10−10]//ED fiber texture through high-energy grain boundary segmentation. Subsequently, compatible stress increases due to the activity of non-basal slip dislocation and the reduction in grain boundary (GB) size. DDRX emerges as the dominant mechanism, generating randomized [10−10]//ED fiber and non-fiber textures within parent grains and at boundaries.

The effect of solid solution treatment with coating on corrosion properties of AZ91 Mg alloy in simulated body fluid

The current study involves an attempt to reduce the corrosion rate of AZ91 Mg alloy that is used in biomedical applications, where it is known as biodegradable material and needs to increase its lifetime until healing can occur. Firstly, solid solution treatment at 450 °C for 8 hr. was worked to reduce the second phase represented by Mg17Al12 and then reduce the galvanic cells on the alloy’s surface. Secondly, coating with indium and titanium metals was done by DC sputtering. The characterization of treated and treated/coated specimens was accomplished by XRD, SEM/EDS, and AFM confirming the improvement of solid solution treated/In coated alloy surface compared with the treated uncoated and solid solution treated/Ti coated alloy. Corrosion properties were investigated by potentiostatic measurement indicating that the solid solution treated/In coated alloy gave lower corrosion current density (i.e., lower corrosion rate), protection efficiency equal to 38.31%, polarization resistance increased from 33.482 × 102 to 36.876 × 102 Ω.cm2 and lower porosity compared with coated specimen by Ti. The reason for this improvement comes from the full coverage of the surface by a compact regular layer of indium as well as the formation of the Mg3In phase. The porosity percentage PP% showed the high porosity for treated/Ti coated specimen which reached to 2104.1%.

Effect of CMT-WAAM Process Parameters on Bead Geometry, Microstructure and Mechanical Properties of AZ31 Mg Alloy

Effect of CMT-WAAM Process Parameters on Bead Geometry, Microstructure and Mechanical Properties of AZ31 Mg Alloy

The Effect of Surface Mechanical Attrition Treatment Time on Microstructure and Mechanical Properties of AZ31 Mg Alloy

The Effect of Surface Mechanical Attrition Treatment Time on Microstructure and Mechanical Properties of AZ31 Mg Alloy

Insight into the microstructural characteristics and corrosion properties of AZ31 Mg alloy coated with polyurethane containing nanostructures of copper metal organic frameworks

Herein, the polyurethane (PU) polymer containing of copper metal–organic frameworks (Cu-MOFs) nanostructures coated on magnesium alloy (Mg AZ31) substrates (AZ/Cu-MOFs/PU) was prepared by using simple dip-coating method. Then, different characterizations were performed to determine the composition, morphology, structure, and wettability of the coatings. The compact PU coatings progress the anti-corrosion effect due to the functional groups of surfaces. Based on the electro-chemical tests, prepared coating has superior corrosion behavior compared to bare sample (AZ31). The dense and compact polymer containing Cu-MOFs coatings prevents the penetration of destructive ions to the surface of AZ31 alloy, which leads to the inhibition effect and improved corrosion behavior.

Effect of Vanadium Nitride (VN) Particles on Microstructure and Mechanical Properties of Extruded AZ31 Mg Alloy

The effect of vanadium nitride (VN) particles additives on microstructure and mechanical properties of the extruded AZ31 Mg alloy was systematically investigated. The experimental results revealed that the addition of 0.5 wt% VN decreased the average grain size of AZ31 Mg alloy from 6.4 to 4.9 µm. With the increase in VN content, the refining effect would weaken because excessive VN particles would negatively affect the dynamic recrystallization process of the alloys. The scanning electron microscopy and energy-dispersive spectroscopy indicated that AlN, VN and Al–V–N particles with different morphologies were distributed in the streamline along the extrusion direction during the extrusion process. The mechanical properties of AZ31 Mg alloy vary with the addition of VN. The extruded AZ31 + 0.5 wt% VN Mg alloy possesses an excellent combination of high strength and ductility. The yield strength and ultimate tensile strength of the extruded AZ31 + 0.5 wt% VN Mg alloy were increased without sacrificing ductility. This is mainly due to the grain refinement caused by double-heterogeneous nucleation particles. With a further increase in VN content, the presence of excessive VN particles increases the stress concentration, and the initiation source of microcracks in the alloy during alloy deformation makes the cracks more easily propagated and results in a decrease in the ductility of the extruded alloy.

Anionic assisted incorporation of WO3 nanoparticles for enhanced electrochemical properties of AZ31 Mg alloy coated via plasma electrolytic oxidation

The present work examined the influence of anion type on incorporating WO 3 into the MgO layer produced via plasma electrolytic oxidation of AZ31 Mg alloy. Here, three different anions, such as aluminate (AlO 2 - ), silicate (SiO 3 2- ), and phosphate (PO 4 3- ) were added separately into an alkaline electrolyte containing WO 3 nanoparticles. The microstructural observations revealed that the incorporation of the WO 3 nanoparticles is affected by the diameter of discharge channels associated with the type of anion added into the electrolyte. The sample produced from phosphate electrolytes had higher thickness but was more porous than those obtained in aluminate or silicate electrolytes. Regardless of anion type, the amounts of WO 3 nanoparticles incorporated into the inner layer of PEO coating were more significant than those incorporated into the outer layer, where a WO 3 -rich inner layer was obtained in the case sample coated in electrolyte with silicate anions. The electrochemical measurements in a 3.5 wt% NaCl solution indicated that the corrosion resistance of the sample coated in silicate electrolyte was superior to other samples in which the sample coated in phosphate electrolyte exhibited the lowest corrosion resistance. This behavior is explained by a mechanism in which every anion produces its microstructural defects under the influence of discharge types, such as type-A, B, C, D, and E, thus, affecting the physical incorporation of WO 3 into the MgO layer under plasma conditions. • Incorporation of WO3 nanoparticles is affected by the anion type. • The anion type affects the types of plasma discharges developed during PEO. • WO3 nanoparticles affected by discharge type affiliated with particular anion. • Effect of SiO3 2- anions on the corrosion behavior of PEO coating is significant

Improving the corrosion behavior of magnesium alloys with a focus on AZ91 Mg alloy intended for biomedical application by microstructure modification and coating.

Magnesium alloys such as AZ91 have received much attention due to their attractive properties, including biocompatibility and lightness. Although magnesium is a potential candidate for implant application, due to its rapid degradation in the physiological environment, there are still some challenges to using it as biocompatible implants. In this regard, various techniques such as microstructure modification and coating are utilized to moderate the degradation rate of magnesium alloys. Therefore, efforts are being made to conduct more extensive research to produce magnesium implants with acceptable corrosion resistance. In this literature review, an overview of the history of research on the corrosion behavior, biodegradability, microstructure deformation mechanisms, crystallographic texture in magnesium alloys with a focus on AZ91 Mg alloy, is provided. In addition, the necessity of improving the properties of AZ91 Mg alloy by the two methods of improving microstructure and coating, and existing innovations in these methods are investigated.

Influence of 2,6-dihydroxybenzoic acid on the corrosion behavior and discharge performance of AZ31 Mg alloy

The influence of different concentrations of 2,6-dihydroxybenzoic acid (2,6-DHB) on corrosion performance and discharge properties of AZ31 Mg alloy is studied by means of EIS, potentiodynamic polarization and half-cell discharge test. It was found that low concentration of 2,6-DHB (0.01 M) can enhance the corrosion resistance of Mg alloy, since it acts as complexing agent to decrease the self-corrosion rate and suppress cathodic hydrogen reaction. High amount of additive in NaCl solution accelerates the dissolution rate of the substrate, leading to deteriorated corrosion performance. The discharge properties of the Mg anode have been greatly modified by the presence of 2,6-DHB. 76.86% of utilization efficiency and 1668.17 mAh g−1 of specific capacity have been achieved for AZ31 Mg alloy in 3.5 wt % NaCl solution with addition of 0.01 M organic additive. High amount of complexing agent promotes self-corrosion and dissolution rate of the substrate, which is detrimental to the discharge properties of the anode.

Optimisation of Corrosion behaviour and hardness of Ni-B4C Composite coated AZ31 Mg alloy using RSM

The optimisation of process parameters in the electroplating process is imperative to improve the effectiveness of coating that meets the industry’s requirements. The present study analyses the influence of the electroplating parameters such as bath temperature, current intensity, and plating time on the hardness and corrosion properties of AZ31 Mg alloy. A preliminary electroplating coating was initially done on the AZ31 Mg alloy with zinc and copper. Subsequently, the AZ31 Mg alloy is coated with Ni-B4C composite by electroplating. Response Surface Methodology (RSM) is used to find the optimum settings for the parameters by minimising the corrosion loss and maximising the hardness. The quadratic regression models were developed for the responses based on the experiments conducted as per the Box-Behnken design method. Scanning Electron Microscopy (SEM), XRD analyses are used to investigate the effectiveness of the Ni–B4C composite coating on AZ31 Mg alloy. It is revealed from the results that the maximum hardness of 140 HV and minimum corrosion mass loss of 0.583 mg cm−2 was obtained for the optimal parameters.

Comparison of the Effect of Equal Channel Angular Pressing, Expansion Equal Channel Angular Pressing, and Hybrid Equal Channel Angular Pressing on Mechanical Properties of AZ31 Mg Alloy

Comparison of the Effect of Equal Channel Angular Pressing, Expansion Equal Channel Angular Pressing, and Hybrid Equal Channel Angular Pressing on Mechanical Properties of AZ31 Mg Alloy

Effect of calcium oxide particle size on microstructure and properties of AZ91 Mg alloy

The effects of calcium oxide (CaO) particle size on the microstructure and properties of AZ91 alloy were investigated using commercial AZ91 (Mg-9Al-1Zn, wt%) alloy and CaO nano (50 nm), sub-micro (200 nm, 500 nm) and micro (1000 nm) particles as grain refiners. The results showed that the grain size of AZ91 alloy decreased non-linearly with the increase of CaO particle size from nano to micro. When the particle size was sub-micro (500 nm), the grain size decreased from 167.8 µm to the lowest value of 33.7 µm. Due to the in-situ replacement reaction between CaO and Mg matrix, a newly formed Al2Ca phase distributed uniformly, consuming elemental Al, which greatly reduced the content of the β-Mg17Al12 phase. As a result, AZ91-CaO500 nm alloy has relatively high mechanical properties and corrosion resistance. In addition, the research revealed that nano-CaO particles were too small to melt into AZ91 alloy completely and undissolved CaO particles residual in the form of a mixed aggregate, resulting in lower mechanical properties and corrosion resistance of AZ91-CaO50 nm alloy compared with AZ91-CaO500 nm alloy, and even lower than other alloys in this study.

Influence of Electrostatic Field on the Microstructure and Mechanical Properties of AZ91 Mg Alloy during Ageing Treatment

The effects of electrostatic field on the microstructure and mechanical properties of AZ91 alloy during ageing treatment are studied. It is shown that electrostatic field can modify the precipitate distributions. With the help of electrostatic field (intensity 4 kV cm−1), the continuous precipitate (CP) is refined, whereas the discontinuous precipitate (DP) is suppressed to some extent. The tensile yield strength of peak‐aged AZ91 alloy is improved from 156 to 169 MPa. The mechanism by which the electrostatic field modifies the precipitate distributions is discussed via the resistivity data combined with the classical theory of vacancy‐dominant diffusion. It is shown that the electrostatic field probably enhances the bulk diffusion and then improves the competitiveness of CP against DP.

Microstructure and mechanical properties of AZ91 Mg alloy fabricated by cold metal transfer additive manufacturing

Based on the cold metal transfer (CMT) technique, AZ91 thick-walled component was fabricated by weaving wire and arc additive manufacturing (WAAM). The results showed that the deposited sample consisted of equiaxed grains with different sizes, and the sample was mainly composed of α-Mg, β-Mg17Al12 and Al8Mn5 phases. The anisotropy of the ultimate tensile strength between the transverse and longitudinal tensile samples was 2.0%, and the fracture surfaces exhibited typical ductile fracture characteristics. The component fabricated by the CMT-based WAAM system has better performance than the traditional cast alloy.

Improved tensile properties of AZ31 Mg alloy subjected to various caliber-rolling strains

Abstract A multi-pass caliber rolling has attracted attentions as an alternative to severe plastic deformation processes. The present study enhanced strength and ductility of AZ31 Mg alloy simultaneously through the application of caliber rolling. The improving trends in tensile properties were interpreted with various caliber-rolling strains. The oval/circular-shaped calibers imposed a high plastic strain at the center of cross-section, leading to effective grain refinement to submicron scale. This work also confirmed the texture randomizing effect of caliber rolling. Such microstructural evolutions gave rise to the fabrication of high-strength material. Moreover, the caliber-rolled AZ31 Mg alloys exhibited an improvement in ductility as compared to the as-received sheet-rolled material. This was discussed in terms of activation of non-basal slip systems and suppression of mechanical twinning. This study successfully proved the possibility of caliber rolling to produce a bulk Mg rod with enhanced tensile properties.

High Mechanical Properties of AZ91 Mg Alloy Processed by Equal Channel Angular Pressing and Rolling

Mechanical properties usually take precedence for wrought magnesium alloy when it would be used as a structure material. This paper proposed an approach that achieved high strength in AZ91 Mg alloy. The main procedure combined solution heat treatment, equal channel angular pressing (ECAP), and the subsequent low temperature rolling. After solution heat treatment and ECAP, the alloy had fine grains and excellent ductility, which benefited the following rolling at low temperature. By the following rolling (at 150 °C), the strength was further increased to ~432 MPa with a moderate ductility. This approach was proved effective in refining the grains and accumulating dislocations. The ultrahigh strength was attributed to the high density of dislocations and fine structure. The uniformly distributed fine precipitates also supplied precipitate hardening. Recrystallization that happened during rolling and annealing was the main reason for the moderate ductility.

Microstructure and Mechanical Properties of AZ31 Mg Alloy Fabricated by Pre-compression and Frustum Shearing Extrusion

The AZ31 Mg alloys were processed by 6% pre-compression and frustum shearing extrusion at various temperatures, and the microstructure, texture and mechanical properties of the resulting alloys are systematically investigated. The results show that the grain size monotonically increases from 6.4 to 12.6 μm and the texture intensity increases from 6.7 to 9.6 with the increase in the extrusion temperature. The combining effect of the pre-twinning and the frustum shearing deformation is found to contribute to the development of the weak basal texture in Mg alloys. The Mg alloy sheet produced at the extrusion temperature of 563 K exhibits excellent mechanical properties. The yield strength, ultimate tensile strength and elongation for the extruded alloys are 189.6 MPa, 288.4 MPa and 24.9%, respectively. Such improved mechanical properties are comparable or even superior to those of the alloys subjected to other deformation techniques, rendering the pre-compression and frustum shearing extrusion a promising way for further tailoring properties of Mg alloys.

Multimodal Microstructure and Mechanical Properties of AZ91 Mg Alloy Prepared by Equal Channel Angular Pressing plus Aging

Developing cost-effective magnesium alloys with high strength and good ductility is a long-standing challenge for lightweight metals. Here we present a multimodal grain structured AZ91 Mg alloy with both high strength and good ductility, prepared through a combined processing route of low-pass ECAP with short-time aging. This multimodal grain structure consisted of coarse grains and fine grains modified by heterogeneous precipitates, which resulted from incomplete dynamic recrystallization. This novel microstructure manifested in both superior high strength (tensile strength of 360 MPa) and good ductility (elongation of 21.2%). The high strength was mainly attributed to the synergistic effect of grain refinement, back-stress strengthening, and precipitation strengthening. The favorable ductility, meanwhile, was ascribed to the grain refinement and multimodal grain structure. We believe that our microstructure control strategy could be applicable to magnesium alloys which exhibit obvious precipitation strengthening potential.

Microstructure and mechanical properties of AZ31 Mg alloy produced by a new compound extrusion technique

Abstract A new extrusion technique, integrated dual-directional extrusion and spiral deformation(DDES), is proposed and successfully applied to AZ31 Mg alloys with no cracks present in the alloys. Combining finite-element analytic, optical microscopy, and X-ray diffraction techniques, it is found that the DDES process may cause cumulative strains of 1.88 in Mg alloy billet. The average grain size of the alloys can be refined from 300 μm to 3.5 μm at a temperature of 573 K, and the basal texture is also dramatically weakened from 53.6 to 6.52. These improvements are mainly attributed to dynamic recrystallization induced by heavily accumulated strain at the spiral region. Further compressive tests are carried out on processed AZ31 Mg alloys, and the superior compressive strength and fracture strain can attain 395 MPa and 30.6 %, respectively, rendering this new deformation technique into a promising approach for further governing properties of Mg-based alloys.