AZ91D Magnesium Alloy Research Articles

Optimization of Mg-Al Layered Double Hydroxide Film Preparation and Corrosion Resistance Study on AZ91D Mg Alloy by Multivariate Polynomial Regression Fitting.

Layered double hydroxide (LDH) films have received extensive attention for their unique physical barrier function and ion exchange properties, which make them promising candidates for corrosion protection of magnesium alloys. In this paper, we used the multiple polynomial regression fitting method to establish a regression equation for the electrochemical corrosion resistance with the reaction temperature (T), pH, and reaction time (t) of the Mg-Al LDH film on the AZ91D magnesium alloy. The goodness of fit, confidence, and residual analyses confirmed the high accuracy of the model equation. According to the calculation using the fmincon function, the best corrosion resistance of the prepared samples could be achieved when the parameters are T = 135 °C, pH = 12.0, and t = 15 h. Then, the experimental results showed that the corrosion current density (Icorr) of the obtained LDH film under the above conditions could be 1.07 × 10-7 A/cm2, approximately 3 orders of magnitude lower than the magnesium alloy substrate, after immersion in a 3.5 wt % NaCl solution for 180 h, the surface structure of the LDH film did not change significantly, and the Icorr was still 2 orders of magnitude higher than that of the magnesium alloy substrate. Hence, a synergistic effect equation for the reaction temperature, pH, and reaction time on the corrosion resistance of the LDH film on a magnesium alloy surface prepared by the hydrothermal method was obtained. Moreover, using this equation, we obtained an LDH film with good corrosion resistance and durability, providing theoretical guidance for optimizing the process of preparing the LDH film by the hydrothermal method in practical applications.

EFFECT OF OUTPUT VOLTAGE ON AN AZ91D MAGNESIUM ALLOY ROLLED USING AN ELECTRIC PULSE TREATMENT

Magnesium alloys have poor deformation properties at room temperature, and the application of an electric pulse current during deformation can improve the plastic-forming ability. In this study, the electric pulse rolling of AZ91D magnesium alloy specimens has been examined by changing the pulse output voltage. The results demonstrate that the best surface quality and lowest content (8.4 %) of the β-Mg17Al12 phase are achieved at an output voltage of 300 V. EBSD tests have revealed the lowest weave strength on {0002} and {100} at a pulse output voltage of 300 V, as well as the greatest enhancement of twinning. The maximum tensile strength was 165 MPa at an output voltage of 300 V, with a maximum elongation of 4.1 % at an output voltage of 200 V.

Additive manufacturing of WE43 and modified AZ91D magnesium alloys using the laser engineered net shaping process

Magnesium alloys WE43 and AZ91D offer weight savings for structural applications. WE43 contains rare-earth elements such as yttrium and neodymium, whereas AZ91D and the AZ class of alloys are lower-cost containing aluminium and zinc. This work uses a modified version of the latter, identified as AZ91D*, where calcium and yttrium have been added. Laser Engineered Net Shaping (LENS) equipment was used to investigate the 3D printing behaviour of gas-atomized WE43 and AZ91D* material. Process evaluations were first done using single track laser scans across wrought substrates of WE43 and AZ31. Process parameters were then developed that enabled deposition of build coupons with less than 1% porosity. These were used for microstructural and mechanical property assessments. The energy densities used were in the range of 40 – 60 J/mm² for AZ91D*, while for WE43 a value of 50 J/mm² was selected. A focus of the work was managing the tendency of magnesium materials to fume heavily during deposition, while achieving a deposit with close to nominal density, i.e. having a low incidence of voids or other micro- or macro-structural defects. The porosity of AZ91D* builds did not seem to correlate with increasing deposition energy density, however WE43 builds did, up to a practical limit imposed by generation of excessive fume. WE43 generated much less fume than AZ91D*. Analysis of the input powder materials indicate the presence of oxides on the particle surfaces. The WE43 powders had a noticeable shell of yttrium oxide. The microstructures of WE43 builds show the presence of arc-shaped structures that are likely the same yttrium oxides, partially, or fully ‘unfolded’. Tensile testing was conducted on WE43 build coupons to assess the effect of a T6 heat treatment. The effect on the ultimate tensile and yield strengths was negligible, however the % elongation at break almost doubled. Inspection of the fracture surfaces suggests this was due to a change in mechanism from fracture initiation at sites of lack-of-fusion/un-melted particles, to a more ductile micro-void coalescence. Furthermore, a not previously described microstructure anomaly was observed: the presence of pure elemental magnesium crystallites and films on the fracture surface. These are attributed to condensation of magnesium vapour on previously built layers and are a possible reason for the existence of lack-of-fusion defects. The in-depth study of process fundamentals will enable future work on process fume inhibition based on process optimization and alloy composition with the goal of producing parts for biomedical and lightweighting applications.

Fabrication of SiC particle dispersed AZ91D magnesium alloy composite by injection molding method and their properties

Fabrication of SiC particle dispersed AZ91D magnesium alloy composite by injection molding method and their properties

Experimental investigation on the wear characteristics of TiC-Co composite coating deposited on AZ91D Mg alloy substrate by plasma transferred arc (PTA) welding process

Abstract In this investigation, a plasma transferred arc (PTA) cladding process was employed to deposit TiC-Co composite coatings on substrate of AZ91D magnesium (Mg) alloy. The morphology and phases of the recently produced composite coatings were examined using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The microhardness and wear rate were evaluated by Vickers microhardness tester and pin-on-disc wear and friction test apparatus at the room temperature respectively. The results demonstrate that dense, uniform, and crack free coatings, with good metallurgical bonding to the AZ91D Mg alloy substrate were formed. The most of the phases present in composite coatings were TiC, Mg, CoTi, α-Co, AlCo, Al3Ti, and Co3C. The maximum average micro-hardness of TiC-Co composite coating was found to be about 1743 HV, which depends on the PTA currents. Whereas, average micro-hardness of the AZ91D Mg alloy substrate was 65 HV. This indicates that the coated layer produced increase in hardness about 27 times of substrate hardness. The cladding layer exhibited a wear rate of 4.94×10-8 g/N-m, whereas the wear rate of the AZ91D Mg alloy substrate was 58×10-8 g/N-m. This indicates that the wear resistance of cladding layer was 12 times higher as compared to AZ91D Mg alloy substrate. The enhanced micro-hardness and wear resistance of TiC-Co composite coating can be attributed due to the formation of ceramic and intermetallic compounds, unveiling its superiority over the AZ91D substrate.

Effects of plasma electrolytic oxidation on fatigue strength of thixomolded AZ91D magnesium alloy

Effects of plasma electrolytic oxidation on fatigue strength of thixomolded AZ91D magnesium alloy

The influence of ultrasonic assistance and laser melting on the microstructure and properties of AZ91D magnesium alloy

The study investigates the effects and mechanisms of laser melting and ultrasound-assisted laser melting treatments on the microstructure and properties of AZ91D magnesium alloy. The findings indicate that the grain size of the samples subjected to laser melting and ultrasound-assisted laser melting is decreased to 40.89 μm (number fraction) and 54.14 μm (area fraction), and 23.21 μm (number fraction) and 29.56 μm (area fraction), respectively. The decrease in grain size can be ascribed to the rapid melting and solidification of the sample surface caused by the high-energy laser beam. This leads to a notable rise in nucleation rate and the development of smaller grains. The effectiveness of laser melting is further enhanced with the introduction of ultrasound. The average microhardness of the samples subjected to laser melting and ultrasound-assisted laser melting shows a significant improvement. Furthermore, the microhardness distribution of the sample subjected to ultrasound-assisted laser melting exhibits greater uniformity. The wear resistance of the samples subjected to laser melting and ultrasound-assisted laser melting shows a significant improvement, as indicated by the friction coefficients of 0.688 and 0.382, respectively. These values represent only 50.7 % and 28.15 % of the friction coefficient of the untreated samples. The improvement of wear resistance can be attributed to the enhancement and homogenization of the microhardness of the samples. The application of laser melting treatment leads to an enhancement in the corrosion resistance of the sample primarily as a result of microstructure densification. However, the introduction of ultrasound does not lead to further improvement in corrosion resistance, possibly as a result of significant grain refinement, which in turn leads to an increase in high-energy grain boundaries.

Roughness Parameters with Statistical Analysis and Modelling Using Artificial Neural Networks After Finish Milling of Magnesium Alloys with Different Edge Helix Angle Tools

The paper presents the results of a study investigating the roughness parameters Rq, Rt, Rv, and Rp of finished-milled magnesium alloys AZ91D and AZ31B. Carbide end mills with varying edge helix angles were used in the study. Statistical analysis was additionally performed for selected machining conditions. In addition, modelling of selected roughness parameters on the end face for the AZ91D alloy was carried out using artificial neural networks. Results have shown that the tool with λs = 20° is more suitable for the finish milling of magnesium alloys because its use leads to a significant reduction in surface roughness parameters with increased cutting speed. Increased feed per tooth leads to increased surface roughness parameters. Both radial and axial depth of cut has an insignificant effect on surface roughness parameters. It has been proven that finish milling is an effective finishing treatment for magnesium alloys. In addition, it was shown that artificial neural networks are a good tool for the prediction of selected surface roughness parameters after finishing milling of the magnesium alloy AZ91D.

Fabrication and characterisation of AZ91D/TCP reinforced composites by stir casting method

ABSTRACT This study focuses on fabricating and characterizing ceramic composites using AZ91D magnesium alloy reinforced with Tricalcium Phosphate (TCP) particles. Uniform distribution of TCP within the matrix was achieved through conventional stir casting. TCP particles, averaging 63µ, were incorporated at weight fractions ranging from 5% to 15%. Cast into grey cast iron molds, cylindrical rods measuring 14 mm in diameter and 100 mm in length were produced. Investigating the impact of different weight percentages of reinforcements on particulate distribution, matrix-particulate interfacial reactions, and mechanical properties, the study utilized SEM and EDS analyses, revealing uniform TCP distribution indicative of successful fabrication. Evaluation of both reinforced and unreinforced composites showcased improved mechanical properties in TCP-reinforced samples. Additionally, discussion on the factrography of compression specimens provided insights into microstructural features and deformation behavior under compression. In summary, this research significantly advances magnesium alloy-based composites, unlocking potential applications across various industries.

Novel green and ecofriendly route for fabricating a robust corrosion protection coating on AZ91D magnesium alloy

Mg is the lightest structural metal on earth; hence, applications of its alloys have attracted attention from researchers. However, these alloys have poor corrosion resistance, which impedes their use in practice. Many researchers have investigated protective coatings for Mg alloys, but current methods consume much energy, use hazardous substances, or are complex (such as anodizing and micro-arc oxidation). This paper proposes a novel method of creating a durable and protective coating on Mg alloy substrates. The AZ91D Mg alloy was selected for investigation, and a Mn-V-P conversion coating treatment in which voltage of only 5 V was applied for 1 min to enhance the alloy’s corrosion resistance. A compact, single-layer film with uniform thickness was created; the average thickness was 1750 nm. The corrosion resistance of alloys treated with the method and through anodizing treatment was compared. For the novel coating, the corroded area fraction after a 168-h salt spray test was less than 5 %, superior to that for the coating produced through anodizing treatment. The feasibility and potential applications of the novel process are discussed.

Interfacial reaction between AZ91D magnesium alloy melt and mild steel under high temperature

Interfacial reaction between AZ91D magnesium alloy melt and mild steel under high temperature

A contrastive characterization of pure Mg and AZ91D alloy based on the testing of mechanical, corrosion, wear, and erosion properties

Abstract Magnesium alloy of grade AZ91D is utilized for a variety of applications in aircraft design and frames, as well as vehicle engine radiators, bumpers, and suspension components to reduce the weight of automobiles. This research compared the mechanical, corrosion, wear, and erosion resistance of pure Mg to that of AZ91 alloy. The corrosion media was NaCl, NaOH, and MgSO4, and the weight loss method was utilised to evaluate corrosion. The pin-on-disc configuration was utilized to assess the dry sliding wear mechanism of the Pure Mg and AZ91D alloy. Pure monolithic Mg and AZ91D magnesium alloy have a low resistance to wear as a result of an increase in contact temperature brought about by a shift of operational conditions. Erosive wear is caused when solid particles in a liquid or air jet strike a surface. Significantly influencing the erosive wear are particle velocity, impact angle, and erodent particle size. In this work, the erosive wear of AZ91D was studied using an Air jet erosion tester. SiO2 was used as the eroding material, and the flow rate of the eroding material and air was 5 gm min−1. The erosive factor experiments are designed using Taguchi orthogonal array (L16). The erosive factor response is erosion rate and primarily regulated by three factors as angle (30°, 45°, 60°, and 90°), time (5 and 10 min) and, contact pressure (1 and 2 bar). The results of the experiments showed that the rate of wear increased with increasing pressure, and that the angle of impact of the jet at 60° caused the most wear of any of the tested angles. Analysis of variance (ANOVA) shows that time is the most important factor in determining erosive rate for AZ91D. SEM is used to investigate the structure and morphology of worn-out materials, and its findings are then confirmed.

Microstructure, Friction and Wear Behavior and Corrosion Resistance of electroless Double-Layer Ni-P/Ni-Mo-P Coatings on AZ91D Magnesium Alloy

Microstructure, Friction and Wear Behavior and Corrosion Resistance of electroless Double-Layer Ni-P/Ni-Mo-P Coatings on AZ91D Magnesium Alloy

Wear Characteristics of AZ91D Magnesium Alloy under Dry Sliding Condition against Hardened Alloy EN31 Steel Disc

Magnesium alloys are very interesting materials used for engineering applications such as automotive, and aerospace industries. Wear is a degradation of material from surface of the workpiece when it is subjected to sliding motion. Also, coefficient of friction is important factor which affects the rate of wear and application of engineering materials. Wear and friction are important characteristics for making the mechanical components subjected to sliding motion. Hence study of wear and friction phenomenon of engineering materials like magnesium alloy is necessary. In this article tribological characteristics of magnesium alloy AZ91D against hardened alloy EN31 steel as counter disc has been studied. The pin-on-disc (POD) wear and friction test had been used for the analysis of failure of materials under sliding motion. The wear test was performed on 10N, 20N, 30N, and 40 N loads with sliding velocities of 0.42m/s, 0.52m/s, 0.63m/s and 0.73m/s. The effect of the sliding distance and the normal load on the wear rate, wear depth and the coefficient of friction has been investigated. The main wear mechanism was found to be plastic deformation and thermal softening.

One-step preparation of color-tuned surface coatings on magnesium alloy with corrosion resistance

Nowadays, few works have been undertaken to explore the anti-corrosion coatings with tunable surface colors. In order to further expand the industrial application of magnesium alloy, a facile one-step hydrothermal method was applied to AZ91D magnesium alloy to obtain anti-corrosion coatings with diversified colors. The formation mechanism was discussed, and the corrosion resistance of the coating was assessed by electrochemical tests, immersion tests, and salt spray tests. The results show that different coating colors such as yellow, cyan, blue and red can be obtained by varying the type and concentration of reagents. The adhesion of the coating to the magnesium alloy substrate was great, and the corrosion current density of the sample with the best anti-corrosion effect was reduced by three orders of magnitude. This method has practical significance in promoting the development of surface coloring and industrial applications of magnesium alloys.

Simultaneous fabrication of Ti-MoS2 self-lubricating coatings and gradient structures to improve the wear resistance of AZ91D alloys

Magnesium alloys are essential for lightweight manufacturing. Nevertheless, defects such as low hardness and poor wear resistance severely restrict their further applications. Ultrasonic impact treatment (UIT) was used to simultaneously fabricate surface Ti-MoS2 self-lubricating coatings and interior gradient structures on AZ91D magnesium alloy for the first time. The surface morphology and microstructure were investigated, the tribological properties were evaluated at various normal loads, and the formation principles and anti-wear mechanisms of coatings and gradient structures were revealed. The findings indicate that the coatings present a particle-stacking microstructure. The gradient structures were characterized by grain, dislocation, and hardness distribution from greater to lesser along the depth direction. At all loads, the UIT samples exhibited superior anti-wear properties. Compared to untreated samples, the UIT sample's wear volume at 5 N, 15 N, and 25 N loads was reduced by 89.78 %, 84.23 %, and 43.88 %, respectively. The wear surface analysis indicates that the Ti-MoS2 coatings effectively enhance the lubricity of friction surfaces. Additionally, gradient structure works when the coatings fail and reduces the shear deformation, further reducing wear. This work presents a new method for fabricating simultaneously surface coatings and interior gradient structures using UIT, contributing to improving the anti-wear properties of magnesium alloys and enhancing their utilization in lightweight manufacturing fields.

GJO-MLP: A NOVEL METHOD FOR HYBRID METAHEURISTICS MULTI-LAYER PERCEPTRON AND A NEW APPROACH FOR PREDICTION OF WEAR LOSS OF AZ91D MAGNESIUM ALLOY WORN AT DRY, OIL, AND h-BN NANOADDITIVE OIL

In this study, the AZ91D magnesium alloy was worn at different wear conditions (dry, oil, and h-BN nanoadditive oil), loads (10–60 N), sliding speeds (50–150 mm/s) and sliding distances (100–1000 m). Wear losses increased with the increase of applied load, sliding speed, and sliding distance. Wear losses were decreased in the h-BN nanoadditive oil conditions. For the first time, the wear losses were predicted using the hybrid golden jackal optimizer-multi-layer perceptron (GJO-MLP) method proposed in this study, using the experimentally obtained data. In addition, the performance of the proposed method was compared with the whale optimization-MLP (WOA-MLP), genetic algorithm-MLP (GA-MLP) and ant lion optimization-MLP (ALO-MLP) methods, which are widely used in the literature. The results showed that GJO-MLP outperformed other methods with a performance of 0.9784 in [Formula: see text] value.

Effect of nanoparticles adhesion and multipass friction stir processing on metallurgical properties of AZ91D magnesium alloy

In this work, the effect of SiC and Al2O3 nanoparticles and multipass friction stir processing (MPFSP) on the metallurgical properties of AZ91D was carefully investigated and observed a homogenous dispersion of nanoparticles and refined grain size in the processed zone. The presence of the Mg17Al12 intermetallic compound in the MPFSP of AZ91D with SiC and Al2O3 nanoparticles has significant implications for the material’s properties. Mg17Al12 is a typical intermetallic phase formed in magnesium alloys and can profoundly affect thermal, microstructural, and mechanical properties. The intermetallic phase can improve the processed region’s strength due to its inherent hardness and solid solution strengthening effect, resulting in enhanced tensile properties and hardness. As the FSP passes increased, the tendency for reinforcement agglomeration diminished. Before undergoing MPFSP/(SiC + Al2O3), the base metal AZ91D exhibited an ultimate tensile strength (UTS) of 208.36 MPa and a strain percentage 15.72. After implementing MPFSP/(SiC and Al2O3) on AZ91D, the UTS consistently increased with each FSP pass. This effect was evident at the fourth FSP pass, yielding a higher UTS of 284.35 MPa. In essence, this process facilitated a marked enhancement in the metallurgical properties of AZ91D, signifying the efficacy of the MPFSP approach when combined with reinforcement particles. The hardness value was higher when the indenter engaged with Mg17Al12 than α-Mg. The SZ of 4-pass FSP (Al2O3+SiC)/AZ91D reached a maximum hardness value of 69.37 HV, while single-pass FSP (Al2O3)/AZ91D exhibited a minimum value of 64.89 HV.

Surface Quality of AZ91D Magnesium Alloy After Precision Milling with Coated Tools

This study investigates the surface quality of AZ91D magnesium alloy specimens after precision milling. The milling was conducted with the use of TiB2- and TiAlN-coated carbide end mills. The following variables were used in the milling process: cutting speed vc, feed per tooth fz and axial depth of cut ap. The surface quality was analysed based on surface roughness parameters and Abbott-Firestone curves. The results showed that the surface quality after machining depended on the tool coating type and applied machining parameters; the only exception was the axial depth of cut because changes in its value did not have any significant effect on the obtained surface quality. After precision milling, AZ91D specimens were characterized by very low surface roughness parameters. The impact of machining conditions was also evaluated with ANOVA analysis, which confirmed the significant effect of cutting speed and feed per tooth. It also indicated the dependence of the roughness parameters on the tool coating type. The tool coating type and machining conditions did not have any significant effect on the Abbott-Firestone curves. Despite the changes applied, the shape of the curves remained similar. The obtained results provide both theoretical and practical knowledge about the achievable surface roughness of AZ91D magnesium alloy specimens after precision milling.

One-step Preparation of Silicate Coatings on AZ91D Magnesium Alloy Surface for Boosting its Corrosion Resistance

One-step Preparation of Silicate Coatings on AZ91D Magnesium Alloy Surface for Boosting its Corrosion Resistance