Types Of Magnesium Alloys Research Articles

Recent Progress on Atmospheric Corrosion of Field-Exposed Magnesium Alloys

It is well known that the poor corrosion resistance of magnesium alloys is a key factor limiting their application. Field exposure is the most reliable means to evaluate the atmospheric corrosion performance of magnesium alloys. This article reviews the field exposure corrosion behavior of magnesium alloys in typical atmospheric environments (including the marine atmosphere, industrial atmosphere, etc.) in recent years. According to the literature review, it was found that there are significant regional differences in the atmospheric corrosion behavior of magnesium alloys, which is the result of the coupling of multiple factors in the atmospheric environment. By investigating the corrosion rate and corrosion products of different types of magnesium alloys in different environments, the corrosion mechanism of magnesium alloys in different environments was summarized. Specifically, environmental parameters such as atmospheric temperature, relative humidity, CO2, and chloride ion deposition rates in the marine atmospheric environment can affect the corrosion behavior of magnesium alloys. The corrosion of magnesium alloys in different industrial atmospheric environments is mainly affected by atmospheric temperature and relative humidity, as well as atmospheric pollutants (such as SO2, CO2, NO2) and dust. This review provides assistance to the development of new corrosion-resistant magnesium alloys.

Impact of processing parameters in plasma electrolytic oxidation on corrosion resistance of magnesium alloy type AZ91

AbstractThis study aims to investigate the effect of the processing parameters in plasma electrolytic oxidation (PEO) on the corrosion resistance of magnesium alloy type AZ91. The PEO coatings were prepared on the samples using alkaline‐based electrolyte. Both unipolar and bipolar, different frequencies and duty cycles were applied. Corrosion tests, using potentiodynamic polarization, linear and cyclic, and electrochemical impedance spectroscopy techniques, were applied on the as‐received and PEO coated samples. Scanning electron microscopy was used to investigate the surface morphology, for example, micropores, as well as to measure the thickness of the coated layer by changing the processing parameters. The results show that the size of micropores is interrelated to the duty cycle percentage and current polarities, as the higher frequency causes thinner coating layers, with fewer micropores, consequently higher corrosion resistance. In addition, increasing the duty cycle, a denser and more compact coating was obtained. The XRD results showed a missing peak of the α‐Mg phase in a PEO coated sample using bipolar, the highest frequency (1666 Hz), and the highest duty cycle (66.6%). The mils per year calculations showed that the PEO coated has a lower corrosion rate by at least 8 times than the as‐received alloy.

Selecting a material for an aircraft diesel engine block

Selecting appropriate materials is presently a complex task as material databases cover tens of thousands of different types of mate-rials. Product designing proceeds in numerous stages and in most of them there are open questions with not only one correct solution but better and worse ones. This paper overviews the Diesel engine body construction materials mentioned in the literature and discusses a certain practical method to select materials for a cylinder head and a Diesel engine block as a prototype. The engine body, depending on its purpose, is most frequently iron or aluminum. If it is important to optimize parts to achieve low weight, aluminum alloys are usual-ly applied, especially in the automotive and aviation industries. In the latter case, weight is even more important so new types of magne-sium alloys which are even lighter than aluminum ones are developed and used. However, magnesium alloys are, for example, more flammable and not enough strong so, for safety reasons, this type of material is not used solely in engine bodies.

Improvement of energy absorption on magnesium alloy mixed carbon-nanotube and lead reinforcement materials in terms of high velocity impact

This paper presents the fracture behaviour of magnesium alloy (AZ31B) with the reinforcement of carbon-nanotube (CNT) and lead subjected ballistic impact. Magnesium alloys are material that can absorb impact energy, however the absorption energy can be increased with the alloy reinforcement with nano-partial. This paper leads to two parts which are experiment and simulation of gas gun. The projectile used was a cone-nose type with diameter of 11 mm made by steel series 1006. The simulation used Cowper-Symonds model to see material behaviour with 25 mm thickness. The correlation of the experiment and simulations was evaluated to see the accuracy of simulations made. It was shown that the value of R2 was 0.9588 where simulation can be used to predict the ballistic impact on 600 m/s velocity. From the simulation results, it was found that the depth of penetration for Magnesium alloy AZ31B reinforced with CNT and Pb showed good agreement findings. The depth of penetrations onto the simulation were obtained between 15 to 25 mm. The added reinforcement materials provide a reduction in the depth of penetration of 40% compared to the original Magnesium alloy AZ31B. Thus, this type of magnesium alloy reinforced with CNT and Pb is suitable for ballistic resistant panel with weight saving determination on armoured vehicle.

Results of <i>In Vivo</i> Biological Tests Performed on a Mg-0.8Ca Alloy

Biodegradable magnesium-based alloys shows good prospects in their use as biodegradable orthopedic materials. The aim of this study is to demonstrate good biocompatibility and lack of local and systemic toxicity of some experimental implants made by magnesium alloy type Mg-Ca 0,8 [%wt]. The study was conducted by implanting some experimental pins made by magnesium alloy type Mg-Ca 0,8 [%wt] in bone, proximal femur and intramedullary tibia, and in thigh muscle of the rabbits. Also, we follow the evolution of blood levels of Mg, Ca, blood counts, liver and kidney function. The evolution of the experience animals was followed for 6 weeks by radiologic imaging, and taking blood samples. After 6 weeks, we obtain after euthanasia of animal experience the harvest blood samples, and musculoskeletal tissue samples for histopathological examination. The histopathology results have not demonstrated peri-implant cytotoxicity, bone and muscle cells being viable. Fibrosis at tissue implant border was minimal showing a good integration. There were no pathological increases in blood levels of Mg and Ca, or changes in blood counts, as well as no change in renal or hepatic function. All this experimental results demonstrates that the magnesium alloy type Mg-Ca 0,8 [%wt] represent a promising solution in orthopedic surgery, proving to be safe, with a high degree of biocompatibility, and without toxic effects.

Predicting the Warm Forming Behavior of WE43 and AA5086 Alloys

In the present work, we have studied the formability behaviour of two types of magnesium alloys, WE43 hot rolled and WE43 cold rolled by carrying out uniaxial tensile test at elevated temperatures of 350°C to 500°C both experimentally and numerically at a constant strain rate of 10-3s-1. Finite element (FE) model is simulated in ABAQUS/CAE 6.7-6 using coupled temperature-displacement step at higher temperature considering material's property to be isotropic in nature. The effect of temperature on maximum flow stress and major strain at onset of necking is discussed. The true stress-strain behaviour and necking evolution through strain mapping are predicted from FE model and compared with the experimental results. The results show that with increase in temperature, the maximum flow stress decreases and necking delays with increase in limiting major strain for the Magnesium alloys. The work has been extended to predict the forming limit strains of Al 5086 alloy only on the negative minor strain region using M-K (Marciniak and Kuczynski) concept. An FE model based on M-K concept is simulated at 20°C, 150°C and 200°C using coupled temperature-displacement step considering anisotropic sheet material. A groove is created in the middle of the model with an optimizedf value of 0.99, after much iteration. The forming limit strains from such FE simulations are compared with the available experimental data. The results are encouraging providing scope for further improvements in modelling.

A preliminary study for novel use of two Mg alloys (WE43 and Mg3Gd).

In this study, two types of magnesium alloys (WE43 and Mg3Gd) were compared with Heal-All membrane (a biodegradable membrane used in guided bone regeneration) in vitro to determine whether the alloys could be used as biodegradable membranes. Degradation behavior was assessed using immersion testing with simulated body fluid (SBF). Microstructural characteristics before and after immersion were evaluated through scanning electron microscopy, and degradation products were analyzed with energy dispersive spectrometry (EDS). To evaluate the biocompatibility of the three types of materials, we performed cytotoxicity, adhesion, and mineralization tests using human osteoblast-like MG63 cells. Immersion testing results showed no significant difference in degradation rate between WE43 and Mg3Gd alloys. However, both Mg alloys corroded faster than the Heal-All membrane, with pitting corrosion as the main corrosion mode for the alloys. Degradation products mainly included P- and Ca-containing apatites on the surface of WE43 and Mg3Gd, whereas these apatites were rarely detected on the surface of the Heal-All membrane. All three type of materials exhibited good biocompatibility. In the mineralization experiment, the alkaline phosphatase (ALP) activity of 10 % Mg3Gd extract was significantly higher than the extracts of the two other materials and the negative control. This study highlighted the potential of these Mg-REE alloys for uses in bone regeneration and further studies and refinements are obviously required.

Structure of butt joint of as-cast magnesium alloys

The article presents a structural analysis of joints of as-cast magnesium alloys created using three joining methods: friction stir welding, CO2 laser welding and electric arc welding in inert gas shielding using tungsten electrode (TIG). The macro- and microstructures of the butt joints have been evaluated using an optical microscope with a digital image recording system. Two types of magnesium alloys were used in the research: AZ91 and AM-Lite, the main alloying elements of which are zinc and aluminium. The starting material consisted of cast ingots milled to a specific dimension and then cut into plate samples with a thickness of 3 mm. The subsequent analysis showed that it is possible to achieve high-quality joints of magnesium alloys. However, trace quantities of pores have also been found.

M207 マグネシウム合金AZ31Bにおける散逸エネルギを用いた疲労限度推定(GS1,3,4 材料力学(2),修士研究発表セッション)

M207 マグネシウム合金AZ31Bにおける散逸エネルギを用いた疲労限度推定(GS1,3,4 材料力学(2),修士研究発表セッション)

English

The aim of this study is to investigate the effect of aluminium content on microstructure, tensile properties and work hardenability of Mg-Al-Zn alloys. Two types of magnesium alloys were investigated i.e. AZ31 and AZ61, where the aluminium contents were 3% and 6%, respectively. Microstructure observation revealed that higher aluminium content decreases the grain size and increases the volume of Mg17Al12 precipitations. From the tensile test, AZ61 demonstrated higher yield stress and tensile strength while maintaining the elongation as compared to AZ31. The work hardening rate for AZ61 was also greater as compared to that of AZ31.

The Precision Forging Experiment of Mg Alloy Drop Forging Using Computer Simulation

Rapid development of automotive industry brings increasing demand for die forgings made from non-ferrous metals. Market economy stimulates drop forges to produce forged pieces of highest quality and dimension precision with the accent on reduction in production costs. Precision die forging without flash belongs to progressive and economical technologies of die forgings production. This paper describes an experiment of precision forging in closed die of magnesium alloy type AZ 31. Given alloy type Mg-Al-Zn is suitable for bulk forming and is characterized by good hot formability. Achieved results may be applied in practice at production of longitudinal shaped forgings e.g. levers and connecting rods. In order to verify a design of closed die forging technology regarding the lever-shaped forged piece, simulation program MSC.SuperForge was used. Numeric simulation was significantly helpful at optimization of semi-product shape and dimensions and confirmed correct plastic flow of material in closed die cavity. The objective of this contribution was to point out current trends in searching for economical measures at production of die forgings from alloys of non-ferrous metals.

The Description of Precision Forging Technology in Closed Die of Mg Alloy AZ31 Using Computer Simulation

Automotive industry is nowadays constantly strengthening its dominant position. Its primary objective is to reduce weight of automobiles in order to decrease fuel consumption and amount of harmful pollutant emissions. From the viewpoint of further development in the field of automotive industry, very interesting are the issues of die forgings production from light non-ferrous metals. This article describes research of precision die forging technology in closed die with regard to magnesium alloy type AZ 31. Given alloy type Mg-Al-Zn is suitable for bulk forming and is characterized by good formability at hot conditions. Results of this research may be applied to production of forgings with longitudinal shape, e.g. levers and connecting rods. In order to verify the design of forging technology in closed die for lever-shaped forged piece the simulation program MSC.SuperForge was used. Numeric simulation of die forging process confirmed suitable designed shape and dimensions of semi product and also correct material plastic flow in cavity of closed die.

Friction Stir Welding of Mg and Al Alloys

The work deals with welding of aluminium alloy typeAlMg4,5Mn and magnesium alloy type AZ 31 in solid state by FSW (Friction Stir Welding) process. Experiments were performed in cooperation with VÚZ PI SR (Welding Research Institute Industrial Institute of Slovak Republic) Bratislava, which has available a new installed equipment type FSW LM 060 manufactured in China. Welding parameters and conditions were proposed and approved. Quality of fabricated joints was assessed by optical microscopy, micro hardness measurement and radiographic test - RT. It was supposed that optimisation of welding parameters would allow to fabricate the joints of acceptable quality that might compete to technologies of fusion welding, including welding with concentrated power sources.

Frictional Properties of AZ80 and ZE10 Magnesium Alloys Under Dry and Lubricated Contact Conditions

The frictional properties of two types of magnesium alloys, i.e. AZ80 and ZE10 were investigated. A purpose-developed sheet metal forming simulator was used to conduct the experiments under constant plastic deformation. Both lubricated and dry sliding contact conditions were simulated and the effect of key process parameters such as contact pressure and sliding velocity on the frictional properties of these alloys were investigated. Due to the different sliding velocities, the contact pressure rose during each experiment which enables the measurement of the coefficient of friction for a wide range of contact pressures. The results showed an increase in the friction coefficients of both alloys with increasing contact pressure. Furthermore, a decrease of the friction coefficient was observed for higher sliding velocities.

Model of Microstructure Development in Hot Deformed Magnesium Alloy AZ31 Type

The paper presents a model of microstructure changes elaborated for magnesium alloy type AZ31. In previous papers, the function of flow stress was defined on the basis of uniaxial hot compression tests. On the basis of marked relaxation curves and quantitative tests of structure the softening indicators were defined together with elaboration of equations which describe the changes in the grain size. Marked coefficients of equations were introduced in the code of simulation program. Calculations were conducted for given temperature values from 450 ÷ 250°C and strain rate from 0.01 to 10 s-1, which correspond with rolling temperature range of this alloy. Prepared model will allow the proper choice of parameters in hot rolling process of this alloy to achieve the assumed microstructure.

Improvement and application of neural network models in development of wrought magnesium alloys

Neural network models of mechanical properties prediction for wrought magnesium alloys were improved by using more reasonable parameters, and were used to develop new types of magnesium alloys. The parameters were confirmed by comparing prediction errors and correlation coefficients of models, which have been built with all the parameters used commonly with training of all permutations and combinations. The application was focused on Mg-Zn-Mn and Mg-Zn-Y-Zr alloys. The prediction of mechanical properties of Mg-Zn-Mn alloys and the effects of mole ratios of Y to Zn on the strengths in Mg-Zn-Y-Zr alloys were investigated by using the improved models. The predicted results are good agreement with the experimental values. A high strength extruded Mg-Zn-Zr-Y alloy was also developed by the models. The applications of the models indicate that the improved models can be used to develop new types of wrought magnesium alloys.

An improved neural network model for prediction of mechanical properties of magnesium alloys

An improved neural network model was developed for prediction of mechanical properties in the design and development of new types of magnesium alloys by refining the types of input variables and using a more reasonable algorithm. The results showed that the improved model apparently decreased the prediction errors, and raised the accuracy of the prediction results. Better preprocessing parameters were found to be [0.15, 0.90] for the tensile strength, [0.1, 0.9] for the yield strength, and [0.15, 0.90] for the elongation. When the above parameters were used, the relativity for predicition of strength was bigger than 0.95. By using improved ANN analysis, more reasonable process parameters and composition could be obtained in some magnesium alloys without addition of strontoum.

Mechanical Properties and Microstructure of Magnesium-Aluminum Based Alloys Containing Strontium

The mechanical properties and processing performances of conventional magnesium alloys still could not meet the need of important application fields due to some demerits, such as poor formability, low creep resistance and unsatisfactory strength at elevated temperature. Recent investigations have shown that additions of strontium to magnesium alloys are effective in improving creep resistance of the alloys at temperatures above 150°C, and some new types of magnesium alloys containing strontium have been developed. The mechanical properties and microstructure of magnesium-aluminum based alloys containing strontium are reviewed, and the considerable discrepancy among the research results is discussed. Special attentions are paid to the mechanical properties, compounds and grain refinement of Mg-Al-Sr based alloys. The Sr/Al ratio is thought to be important to control the microstructure of Mg-Al-Sr alloys. The mechanism of grain refinement caused by strontium addition in magnesium alloys remains unclear.

Development of New Types of Magnesium Alloys Containing Sr or RE Elements

The latest research results on new types of magnesium alloys containing strontium or rare earth elements are reviewed. Special attentions are paid to the alloying design, microstructure and properties controlling, the influence of minor addition of Sr and RE on the microstructure and properties of existing magnesium alloys. Some new types of magnesium alloys containing Sr or RE are introduced and discussed.

双ロールキャスタにより作製したマグネシウム合金板の深絞り成形性

Using an isothermal rolling machine with a twin roll caster, sheet materials were fabricated with a thickness of t=0.5 mm from three types of magnesium alloy sheets(namely, AZ61, AZ91 and AM60). The result indicates that sheet materials with a limited number of edge cracks can be fabricated from any of these magnesium alloys by rolling at Tr=300°C or higher. Next, the deep drawability of the thus-obtained rolled thin sheets were examined. Regardless of the type of magnesium alloy, the limiting drawing ratios(LDRs)improved the most for the magnesium alloy sheets rolled at Tr=300°C, at which a uniform and very small grain diameter was obtained. Moreover, the LDRs of AZ61, AZ91 and AM60 sheets rolled at Tr=300°C were 2.7, 2.4 and 2.6, respectively. It became apparant that these magnesium alloy sheets have characteristics sufficient for practical use in deep drawing when rolled under appropriate conditions.