Development of a magnesium alloy with good casting characteristics on the basis of Mg–Al–Ca–Mn system,having Mg–Al2Ca structure

Application of calcium as alloying element for magnesium alloys has been considered according to literature data.Mg–7%Al–4%Ca–0.5%Mn casting alloy was offered,which possesses the low propensity to the hot brittleness and good castability.The alloy has the moderate strength(σu=150 MPa)and the satisfactory percentage elongation(δ=3%).It is shown,that calcium-containing alloys smelting of Mg–Al–Ca–Mn system is preferable with the application of low-chloride flux FL10(20%MgCl_(2);29%KCl;12%BaCl_(2);23%CaF2;15%MgF2;1%B2O3).The alloy smelting in the atmosphere of argon and SF6 mixture results in the increased shelling and waste of calcium.The heat treatment is offered for the developed alloy,which is directed to the Al_(2)Ca phase spheroidizing.The developed magnesium alloy,alloyed with calcium,is perspective for the industry production of low-cost moulding.

Experimental observations on the nonproportional multiaxial ratchetting of cast AZ91 magnesium alloy at room temperature

The nonproportional multiaxial ratchetting of cast AZ91 magnesium (Mg) alloy was examined by performing a sequence of axial-torsional cyclic tests controlled by stress with various loading paths at room temperature (RT).The evolutionary characteristics and path dependence of multiaxial ratchetting were discussed.Results illustrate that the cast AZ91 Mg alloy exhibits considerable nonproportional additional softening during cyclic loading with multiple nonproportional multiaxial loading paths;multiaxial ratchetting presents strong path dependence,and axial ratchetting strains are larger under nonproportional loading paths than under uniaxial and proportional45°linear loading paths;multiaxial ratchetting becomes increasingly pronounced as the applied stress amplitude and axial mean stress increase.Moreover,stress-strain curves show a convex and symmetrical shape in axial/torsional directions.Multiaxial ratchetting exhibits quasi-shakedown after certain loading cycles.The abundant experimental data obtained in this work can be used to develop a cyclic plasticity model of cast Mg alloys.

Effects of process parameters on morphology and distribution of externally solidified crystals in microstructure of magnesium alloy die castings

During the cold-chamber high pressure die casting(HPDC) process, samples were produced to investigate the microstructure characteristics of AM60B magnesium alloy. Special attention was paid to the effects of process parameters on the morphology and distribution of externally solidified crystals(ESCs) in the microstructure of magnesium alloy die castings, such as slow shot phase plunger velocity, delay time of pouring and fast shot phase plunger velocity. On the basis of metallographic observation and quantitative statistics, it is concluded that a lower slow shot phase plunger velocity and a longer delay time of pouring both lead to an increment of the size and percentage of the ESCs, due to the fact that a longer holding time of the melt in the shot sleeve will cause a more severe loss of the superheat. The impingement of the melt flow on the ESCs is more intensive with a higher fast shot phase plunger velocity, in such case the ESCs reveal a more granular and roundish morphology and are dispersed throughout the cross section of the castings. Based on analysis of the filling and solidification processes of the melt during the HPDC process, reasonable explanations were proposed in terms of the nucleation, growth, remelting and fragmentation of the ESCs to interpret the effects of process parameters on the morphology and distribution of the ESCs in the microstructure of magnesium alloy die castings.

Constitutive description for casting magnesium alloy involving void evolution

In order to investigate the effect of microvoids on the mechanical behavior of casting magnesium alloy,a spherical void-cell model of the material was presented.The velocity and strain fields of the model were obtained from the assumption that the material matrix is homogeneous and incompressible.The hardening and softening functions,which respectively reflect the deformation-hardening and void-softening behaviors of the material,were presented and introduced to an endochronic constitutive equation for describing the mechanical behavior of the material including microvoids.The corresponding numerical algorithm and finite element procedure were developed and applied to the analyses of the elastoplastic response and the porosity of casting magnesium alloy ZL102.The computed results show satisfactory agreement with experimental data.

Latest research advances on magnesium and magnesium alloys worldwide

In the past two years,significant progresses have been achieved in high-performance cast and wrought magnesium and magnesium alloys,magnesium-based composites,advanced cast technologies,advanced processing technologies,and functional magnesium materials,such as Mg ion batteries,hydrogen storage Mg materials,bio-magnesium alloys,etc.Great contributions to the development of new magnesium alloys and their processing technologies have been made by Chongqing University,Shanghai Jiaotong University,Chinese Academy of Sciences,Helmholtz Zentrum Geesthacht,Queensland University,Brunel University,etc.This review paper is aimed to summarize the latest important advances in cast magnesium alloys,wrought magnesium alloys and functional magnesium materials worldwide in 2018–2019,including both the development of new materials and the innovation of their processing technologies.Based on the issues and challenges identified here,some future research directions are suggested,including further development of high-performance magnesium alloys having high strength and superior plasticity together with high corrosion resistance and low cost,and fundamental research on the phase diagram,diffusion,precipitation,etc.,as well as the development of advanced welding and joining technology.

Research advances of magnesium and magnesium alloys worldwide in 2021

More than 4000 papers in the field of Mg and Mg alloys were published and indexed in Web of Science(WoS)Core Collection database in 2021.The bibliometric analyses indicate that the microstructure,mechanical properties,and corrosion of Mg alloys still are the main research focus.Mg ion batteries and hydrogen storage Mg materials have attracted much attention.Significant contributions to the research and development of magnesium alloys were made by Chongqing University,Shanghai Jiaotong University,and Chinese Academy of Sciences in China,Helmholtz Zentrum Hereon in Germany,Ohio State University in the United States,the University of Queensland in Australia,Kumanto University in Japan,and Seoul National University in Korea,University of Tehran in Iran,etc..This review is aimed to summarize the progress in the development of structural and functional Mg and Mg alloys in 2021.Based on the issues and challenges identified here,some future research directions are suggested.

Research advances of magnesium and magnesium alloys worldwide in 2022

More than 4600 papers in the field of Mg and Mg alloys were published and indexed in the Web of Science(WoS)Core Collection database in 2022.The bibliometric analyses indicate that the microstructure,mechanical properties,and corrosion of Mg alloys are still the main research focus.Bio-Mg materials,Mg ion batteries and hydrogen storage Mg materials have attracted much attention.Notable contributions to the research and development of magnesium alloys were made by Chongqing University(>200 papers),Chinese Academy of Sciences,Shanghai Jiao Tong University,and Northeastern University(>100 papers)in China,Helmholtz Zentrum Hereon in Germany,Ohio State University in the USA,the University of Queensland in Australia,Kumanto University in Japan,and Seoul National University in Korea,University of Tehran in Iran,and National University of Singapore in Singapore,etc.This review is aimed to summarize the progress in the development of structural and functional Mg and Mg alloys in 2022.Based on the issues and challenges identified here,some future research directions are suggested.

Effects of combined addition of Y and Ca on microstructure and mechanical properties of die casting AZ91 alloy

A series of die casting heat-resistant magnesium alloys based on Mg-Al system were developed for automotive application by adding Y and various amounts of Ca. The mechanical properties and microstructures of die casting AZ91 alloy with combined addition of Y and Ca were investigated by optical microscopy, scanning electronic microscopy, X-ray diffractometry and mechanical property test. The results show that the combined addition of Y and Ca can refine the as-die-cast microstructure, result in the formation of Al2Ca phase and Al2Y phase, and inhibit the precipitation of Mg17Al12 phase. The combined addition of Y and small amount of Ca has little influence on the ambient temperature tensile properties, but increasing the content of Ca can improve significantly the tensile strength at both ambient and elevated temperatures. It is found that for AZ91-1Y-xCa alloy, the hardness and the elevated temperature tensile strength increase, while the elongation decreases with increasing the addition of Ca. The mechanism of mechanical properties improvement caused by the combined addition of Y and Ca was also discussed.

Experimental investigation on uniaxial cyclic plasticity of cast AZ91 magnesium alloy

The uniaxial cyclic plasticity of cast AZ91 magnesium(Mg) alloy was investigated by conducting a series of cyclic straining and stressing tests at room temperature, and a unique cyclic plasticity(especially for ratchetting) and its physical nature were revealed. The experimental results demonstrate that the cast AZ91 Mg alloy behaviors tension-compression symmetry, because the dislocation slipping and twinning occur during both the tensile and compressive deformations;although the cast AZ91 alloy presents a certain pseudo-elastic behavior during unloading due to the detwinning, there is no obvious S-shaped asymmetric hysteresis loop like that of wrought Mg alloy in the cyclic tensile-compressive tests, and an obvious cyclic hardening is observed;moreover, the ratchetting of the cast AZ91 alloy presented in the cyclic stressing tests depends remarkably on the prescribed mean stress and stress amplitude, but slightly changes with the stress rate, and the evolution of responding peak/valley strain greatly differs from that of wrought Mg alloys and stainless steels. This work provides rich experimental data for establishing the constitutive model of cast Mg alloys.

A Review on Casting Magnesium Alloys： Modification of Commercial Alloys and Development of New Alloys

The research and development status of casting magnesium alloys including the commercial casting alloys and the new types casting alloys are reviewed,with more attention to microstructure and mechanical properties of modified-AZ91,AM60 and WE43 alloys with various additions,and new types of low cost casting alloys and high strength casting alloys.The modification and/or refinement of Mg2 Si phase in Mg-Al-Si based casting alloys by various additions are discussed and new purifying technologies for casting magnesium alloys are introduced to improve the performance.The modified AZ81 alloy with reduced impurities is found to have the tensile strength of 280 ± 6 MPa and elongation of 16% ± 0.7%.The fatigue strength of AZ91 D alloy could be obviously improved by addition of Ce and Nd.The Mg-16Gd-2Ag-0.3Zr alloy exhibits very high tensile and yield strengths（UTS：423 MPa and YS：328 MPa）;however,its elongation still needs to be improved.

AZ91 Magnesium Alloy/Porous Hydroxyapatite Composite for Potential Application in Bone Repair

AZ91/HA composite was prepared by AZ91 magnesium alloy and porous HA using squeeze casting method. The microstructure and mechanical property of the AZ91/HA composite were studied. The results show that the molten AZ91 alloy completely infiltrated the preform without destroying the porous structure of the HA preform. The compressive strength of AZ91/HA composite increased significantly compared with that of the porous HA. The immersion test indicated that AzgI ahoy shows a lower corrosion resistance and is easier to be corroded in comparison with HA.