Synergistic effect of gradient Zn content and multiscale particles on the mechanical properties of Al-Zn-Mg-Cu alloys with coupling distribution of coarse-fine grains

This study investigated the influence of graded Zn content on the evolution of precipitated and iron-rich phases and grain struc-ture of the alloys,designed and developed the Al–8.0Zn–1.5Mg–1.5Cu–0.2Fe(wt%)alloy with high strength and formability.With the increase of Zn content,forming the coupling distribution of multiscale precipitates and iron-rich phases with a reasonable matching ratio and dispersion distribution characteristics is easy.This phenomenon induces the formation of cell-like structures with alternate distribu-tion of coarse and fine grains,and the average plasticity–strain ratio(characterizing the formability)of the pre-aged alloy with a high strength is up to 0.708.Results reveal the evolution and influence mechanisms of multiscale second-phase particles and the corresponding high formability mechanism of the alloys.The developed coupling control process exhibits considerable potential,revealing remarkable improvements in the room temperature formability of high-strength Al–Zn–Mg–Cu alloys.

Effects of minor Zn content on microstructure and corrosion properties of Al-Mg alloy

The effects of different Zn contents in Al-Mg alloy on the microstructure characterizations were observed by advanced electron microscopy and the corrosion properties were investigated by the inter-granular corrosion tests,the exfoliation corrosion tests,and the Potentiodynamic polarizaion tests.The τ phase(Mg_(32)(Al,Zn)_(49)) forms on the pre-existing Mn-rich particles and at the grain boundaries.According to the theory of binding energy,the formation of τ phase is much easier than that of β phase(Al_3Mg_2),somehow replacing β phase and reducing the possibility of β phase precipitation.This change dramatically decreases the susceptibility of corrosion.The Zn addition increases the corrosion resistance of Al-Mg alloy with an optimal value of 0.31%.When the Zn addition is increased to 0.78%,however,the corrosion resistance of alloy decreases once again but it is still better than that of the alloy without Zn addition.

Effects of Mg content on microstructure and mechanical properties of low Zn-containing Al-xMg-3Zn-1Cu cast alloys

Effects of Mg content on the microstructure and mechanical properties of low Zn-containing Al−xMg−3Zn−1Cu cast alloys(x=3−5,wt.%)were investigated.As Mg content increased in the as-cast alloys,the grains were refined due to enhanced growth restriction,and the formation ofη-Mg(AlZnCu)_(2) and S-Al_(2)CuMg phases was inhibited while the formation of T-Mg_(32)(AlZnCu)_(49 )phase was promoted when Mg content exceeded 4 wt.%.The increase of Mg content encumbered the solution kinetics by increasing the size of eutectic phase but accelerated and enhanced the age-hardening through expediting precipitation kinetics and elevating the number density of the precipitates.As Mg content increased,the yield strength and tensile strength of the as-cast,solution-treated and peak-aged alloys were severally improved,while the elongation of the alloys decreased.The tensile strength and elongation of the peak-aged Al−5Mg−3Zn−1Cu alloy exceed 500 MPa and 5%,respectively.Precipitation strengthening implemented by T′precipitates is the predominant strengthening mechanism in the peak-aged alloys and is enhanced by increasing Mg content.

Effect of mole ratio of Y to Zn on phase constituent of Mg-Zn-Zr-Y alloys

The phase constituent evolution of Mg-Zn-Y-Zr alloys with the mole ratio of Y to Zn both in the as-cast and as-annealed states at the Mg-rich corner was investigated by XRD and SEM/EDS analysis and was further explained from the ternary phase diagram calculation. The results show that the formation of the secondary phases in Mg-Zn-Y-Zr alloys firmly depends on the mole ratio of Y to Zn, and X （Mg 12 YZn）-phase, W （Mg 3 Y 2 Zn 3 ）-phase and I （Mg 3 YZn 6 ）-phase come out in sequence as the ratio of Y to Zn decreases. The mole ratios of Y to Zn with the corresponding phase constituent are suggested quantitatively as follows： the phase constituent is α-Mg ＋ I when the mole ratio of Y to Zn is about 0.164; α-Mg ＋ I ＋W when the mole ratio of Y to Zn is in the range of 0.164 0.33;α-Mg ＋W when the mole ratio of Y to Zn is about 0.33; α-Mg ＋W＋X when the mole ratio of Y to Zn is in the range of 0.33 1.32; and α-Mg ＋X when the mole ratio of Y to Zn is about 1.32. The results also offer a guideline for alloy selection and alloy design in Mg-Zn-Y-Zr system.

Effect of Zn addition on microstructure and mechanical properties of as-cast Mg-2Er alloy

The effect of Zn addition on microstructure and mechanical properties of the Mg-2Er alloy was investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. The results show that the alloys with 1%and 2%Zn （mass fraction） are composed of the W-phase and theα-Mg matrix. Meanwhile, the addition of 4%-10%Zn results in the formation of the I-phase, the W-phase and theα-Mg matrix. When the addition of Zn reaches 12%, the W-phase disappears and the phase constituents of the alloys mainly include the I-phase and the Mg4Zn7 phase besides theα-Mg solid solution. The alloy containing 6%Zn has better mechanical properties, of which the ultimate tensile strength （UTS） and the yield tensile strength （YTS） are about 224 MPa and 134 MPa, respectively, companying an elongation of 10.4%.

Influences of Dopants on Microstructure and Magnetic Properties of (Mg_(0.476)Mn_(0.448)Zn_(0.007))(Fe_(1.997)Ti_(0.002))O_4 Ferrites

Influences of addition of CaO, CoO and V2O5 on the microstructure and magnetic properties of （Mg0.476Mn0.448Zn0.007）（Fe1.997Ti0.002）O4 ferrites were investigated. The powders of （Mg0.476Mn0.448Zn0.007） （Fe1.997Ti0.002）O4 composition were prepared by using a conventional ceramic powder processing technique. The experimental results showed that the average grain size of the sintered ferrites codoped with 0.03wt% CaO, 0.04wt% CoO and 0.06wt% V2O5 was about 15 μm; the saturation magnetization of ferrites was 68.78 emu/g. The addition of V2O5 in the ferrites can not only increase value of the saturation magnetization, but also decrease the average grain size of （Mg0.476Mn0.448Zn0.007）（Fe1.997Ti0.002）O4 ferrites. Simultaneous incorporation of CoO, CaO and V2O5 dopants into （Mg0.476Mn0.448Zn0.007）（Fe1.997Ti0.002）O4 ferrites can not only improve the saturation magnetization of the materials, but also inhibit abnormal grain growth.

Effect of Pb content on the surface topography and corrosion resistance of hot dip Zn-Al-Mg coatings

In this study,the effect of Pb content on the surface morphology and salt spray corrosion resistance of hot dip Zn-AI-Mg coatings was investigated. The results showed that the coating surface easily formed small grains of zinc spangle structures and that the salt spray con＇osion resistance of the coating decreased when Pb content was greater than 0.01%. The microstructure and energy dispersive spectrum analysis of surface and cross-sectional areas was performed by scanning electron microscopy. Pb content present in the coating was analyzed by glow discharge spectrum. The results showed that the distribution of Pb in the coating was not uniform. The Pb content was segregated on the surface and at the cross-section of the Zn-A1-MgZn2 ternary eutectic structure,especially,on the surface of the Zn-A1-MgZn2 ternary eutectic structure.

The Electrical and Optical Properties of Zn0.5Li2xMg0.5-xFe2O4 Lithium Doped Nanoparticle Prepared by Coprecipitation Method

In this study, nano ferrite materials were produced to replace costive industrial materials [1]. Ferrite nanoparticles are the interesting material due to their rich and unique physical and chemical properties. They find applications in catalysis, bio-processing, medicine, magnetic recording, adsorption, devices etc. Using co-participation method, five nano ferrite samples Zn0.5Mg0.5-xLi2xFe2O4 (x = 0.00, 0.10, 0.20, 0.30 and 0.40) were prepared. The electrical and optical properties of the Zn0.5Mg0.5-xLi2xFe2O4 samples were studied using the Ultraviolet-visible (UV-Vis) spectroscopy. The results verified that the formation of the absorption coefficient of the five samples of Zn0.5Mg0.5-xLi2xFe2O4 increased with the increase of Lithium (Li2x). The energy band gap of the Zn0.5Mg0.5-xLi2xFe2O4 samples ranged from 3.28 to 3.12 eV [1]. The extinction coefficient (K) for five samples of Zn0.5Li2xMg0.5-xFe2O4 increased with the increase of Lithium (Li2x) at 338 nm from 0.074 to 0.207. The high magnitude of optical conductivity is (1.34 × 1012 sec-1) and the maximum value of electrical conductivity is 42 (Ω.cm)-1. This may due to the electrical and optical properties of lithium.

Effects of Zn content on the microstructure and the mechanical and corrosion properties of as-cast low-alloyed Mg–Zn–Ca alloys

The effects of Zn content on the microstxucture and the mechanical and corrosion properties of as-cast low-alloyed Mg-xZn~.2Ca alloys （x = 0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, respectively） axe investigated. The results show that the Zn content not only influences grain refinement but also induces different phase precipitation behaviors. The as-cast microstxucture of the 0.6Zn alloy is composed of ct-Mg, Mg2Ca, and Ca2Mg6Zn3 phases, whereas 2.0Zn and 2.5Zn alloys only contain ct-Mg and Ca2Mg6Zn3 phases, as revealed by X-ray diffraction （XRD） and txonsmission electron microscopy （TEM） analyses. Moreover, with in- creasing Zn content, both the ultimate tensile strength （UTS） and the elongation to fracture first increase and then decrease. Among the three investigated alloys, the largest UTS （178 MPa） and the highest elongation to fracture （6.5%） are obtained for the 2.0Zn alloy. In addition, the corrosion rate increases with increasing Zn content. This paper provides on updated investigation of the alloy composi- tion-microstxucture-property relationships of different Zn-containing Mg-Zn-Ca alloys.

Effect of Zn/Mg/Cu Additions on Hot Cracking Tendency and Performances of Al-Cu-Mg-Zn Alloys for Liquid Forging

During the process of liquid forging, a host of hot cracking defects were found in the Al-CuMg-Zn aluminum alloy. Therefore, mechanical tests and analyses by optical microscope, scanning electron microscope, and X-ray diffraction were performed to research the influences of zinc, magnesium, and copper(three main alloying elements) on hot cracking tendency and mechanical properties. It was concluded that all the three alloying elements exerted different effects on the performances of newly designed alloys. And the impact of microstructures on properties of alloys was stronger than that of solution strengthening. Among new alloys, Al-5 Cu-4.5 Mg-2.5 Zn alloy shows better properties as follows: σb=327 MPa, δ=2.7%, HB=107 N/mm^2, and HCS=40.

Effect of Zn/Mg ratio on cathodic protection of carbon steel using Al-Zn-Mg sacrificial anodes

Al-Zn-Mg alloys with different Zn/Mg mass ratios were evaluated as sacrificial anodes for cathodic protection of carbon steel in 3.5 wt.%Na Cl solution.The anodes were fabricated from pure Al,Zn and Mg metals using casting technique.Optical microscopy,SEM-EDS,XRD and electrochemical techniques were used.The results indicated that with decreasing Zn/Mg mass ratio,the grain size ofα(Al)and the particle size of the precipitates decreased while the volume fraction of the precipitates increased.The anode with Zn/Mg mass ratio>4.0 exhibited the lowest corrosion rate,while the anode with Zn/Mg mass ratio<0.62 gave the highest corrosion rate and provided the highest cathodic protection efficiency for carbon steel(AISI 1018).Furthermore,the results showed that the anode with Zn/Mg mass ratio<0.62 exhibited a porous corrosion product compared to the other anodes.

Comprehensive Analysis of CuIn_1-xGa_xSe₂Based Solar Cells with Zn_1-yMg_yO Buffer Layer

The development of cadmium-free CIGS solar cells with high conversion efficiency is crucial due to the toxicity of cadmium. Zinc-based buffer layers seem to be the most promising. In this paper, a numerical analysis using SCAPS-1D software was used to explore the Zn(Mg,O) layer as an alternative to the toxic CdS layer. The effect of several properties such as thickness, doping, Mg concentration of the Zn(Mg,O) layer on the current-voltage parameters was explored and their optimal values were proposed. The simulation results reveal that the optimal value of the ZMO layer thickness is approximately 40 nm, the doping at 1017 cm-3 and an Mg composition between 0.15 and 0.2. In addition, the effect of Gallium (Ga) content in the absorber as well as the Zn(Mg,O)/CIGS interface properties on the solar cell’s performance was examined. The results show that contrary to the CdS buffer layer, the best electrical characteristics of the ZMO/CIGS heterojunction are obtained using a Ga-content equal to 0.4 and high interface defect density or unfavorable band alignment may be the causes of poor performances of Zn(Mg,O)/CIGS solar cells in the case of low and high Mg-contents.

Influenced of Cu²⁺Doped on Structural, Morphological and Optical Properties of Zn-Mg-Fe₂O₄Ferrite Prepared by Sol-Gel Method

The Zn0.5CuxMg0.5-xFe2O4 (where x = 0.0, 0.1, 0.2, 0.3 and 0.4) was prepared by sol-gel route and characterized in detail in terms of their structural, morphological, elemental and optical properties as a function of Cu concentration. X-ray diffractometer (XRD) results confirmed the formation of cubic spinel-type structure with average crystallized size in the range of 30.56 to 40.58 nm. Lattice parameter was found to decrease with Cu concentration due to the smaller ionic radius of Cu2+ ion. The HR-SEM images show morphology of the samples as prismatic shaped particles in agglomeration. The elemental dispersive X-ray Spectroscopy (EDX) confirmed the elemental composition of the as-prepared spinel ferrite material with respect to the initial concentration of the synthetic composition used for the material. The Fourier transform infrared (FTIR) spectroscopy confirmed the formation of spinel ferrite and showed the characteristics absorption bands around 463, 618, 876, 1116, 1442, 1622 and 2911 cm-1. The energy band gap was calculated for the samples were found to be in the range of 4.87 to 5.30 eV.

Effect of cooling rate and composition on microstructures and properties of Zn-Mg alloys

The Zn-Mg alloys with Mg additions of 35%,40% and 45%(mass fraction) were prepared by conventional casting method,with the aim to develop new biodegradable materials. The effects of cooling rate and composition on the microstructures,hardness and corrosion resistance were studied by XRD,SEM,microhardness and corrosion testing techniques. The corrosion behaviors of experimental alloys in simulated body fluids were analyzed. The results show that the amount of the petal-like MgZn2 phase decreases,as well as the hardness of the alloys,but that of the polygonal MgZn2 phase increases with the increase of Mg content when the cooling rate is constant. When the alloy composition is constant,the MgZn2 phase changes easily from petal-like to polygon,and the hardness decreases with the decrease of the cooling rate.

Effect of Zn on mechanical property and corrosion property of extruded Mg-Zn-Mn alloy

The effect of Zn on the microstructure, the mechanical property and the corrosion property in simulated body fluid(SBF) of an extruded Mg-Mn alloy was studied. The results indicate that the addition of Zn element can significantly refine the grain size of the extruded Mg-Mn alloy. When Zn content is increased from 0% to 3%, the grain size decreases from 12 μm to 4 μm. Meanwhile, the mechanical properties also increase remarkably with increasing Zn content. When Zn content is 3%, the ultimate tensile strength and the yield strength are increased by 54.7 MPa and 69.7 MPa, respectively. Zn can also improve the anti-corrosion property of the alloy. The best anti-corrosion property is obtained with 1% Zn. However, further increase of Zn content up to 3% deteriorates the corrosion property. Finally, the influence mechanism of Zn on the microstructure, the mechanical property and the corrosion property was discussed.

Effects of Fe-Oxide and Mg Layer Insertion on Tunneling Magnetoresistance Properties of CoFeB/MgO/CoFeB Magnetic Tunnel Junctions

To study the influence of CoFeB/MgO interface on tunneling magnetoresistance （TMR）, different structures of magnetic tunnel junctions （MTJs） are successfully prepared by the magnetron sputtering technique and characterized by atomic force microscopy, a physical property measurement system, x-ray photoelectron spectroscopy, and transmission electron microscopy. The experimental results show that TMR of the CoFeB/Mg/MgO/CoFeB structure is evidently improved in comparison with the CoFeB/MgO/CoFeB structure because the inserted Mg layer prevents Fe-oxide formation at the CoFeB/MgO interface, which occurs in CoFeB/MgO/CoFeB MTJs. The inherent properties of the CoFeB/MgO/CoFeB, CoFeB/Fe-oxide/MgO/CoFeB and CoFeB/Mg/MgO/CoFeB MTJs are simulated by using the theories of density functions and non-equilibrium Green functions. The simulated results demonstrate that TMR of CoFeB/Fe-oxide/MgO/CoFeB MTJs is severely decreased and is only half the value of the CoFeB/Mg/MgO/CoFeB MTJs. Based on the experimental results and theoretical analysis, it is believed that in CoFeB/MgO/CoFeB MTJs, the interface oxidation of the CoFeB layer is the main reason to cause a remarkable reduction of TMR, and the inserted Mg layer may play an important role in protecting Fe atoms from oxidation, and then increasing TMR.

Effects of Zn content on as-cast microstructure and mechanical properties of Mg-xZn-4Al alloys containing TiC and rare earth elements

The effects of Zn content on the as-cast microstructure and mechanical properties of Mg-xZn-4Al alloys containing TiC and rare earth elements were investigated by optical microscopy (OM), scanning electron microscopy (SEM) analysis, X-ray diffraction (XRD) analysis and tensile test. The results show that Zn content which increased from 8% to 12% does not obviously influence on the alloy phase type of the Mg-xZn-4Al experimental alloys containing 0.25%RE and l%TiC, but with Zn content increasing from 8% to 12%, the amount of Mg32(Al,Zn)49 phase in the as-cast microstructure of the experimental alloys increases and its distribution becomes more continuous. In addition, the Mg-10Zn-4Al alloy containing 0.25%RE and 1TiC has the highest ultimate tensile strength at room temperature and 150℃and highest yield strength and elongation at 150℃. Furthermore, with Zn content increasing from 8% to 12%, the yield strength and elongation of Mg-xZn-4A1 experimental alloys containing 0.25%RE and 1%TiC increase and decrease at room temperature, respectively.

Phase equilibria of Mg-rich corner in Mg Zn Al ternary system at 300 °C

The phase equilibria and compositions in Mg-rich comer at 300℃ were determined in the Mg-Zn-A1 ternary system through the equilibrated alloy method by using X-ray diffraction （XRD） and scanning electron microscopy （SEM） assisted with energy dispersive spectroscopy of X-ray （EDS）. The results show that there exist three three-phase regions consisted of a-Mg＋Mg17A112（7）＋A15Mg11Zn4（φ）, a-Mg＋Mga2（Al, Zn）49（r）＋A15MgllZn4（φ） and a-Mg＋MgZn＋Mg32（A1, Zn）49（r）, respectively. The intermetallic compounds in equilibrium with a-Mg phase all have large composition ranges, not appear to be linear. At the same time, both zinc and aluminum are soluble in the a-Mg solid solution, with which the compounds are in equilibrium.

Precipitation modification in cast Mg-1Nd-1Ce-Zr alloy by Zn addition

The effects of different Zn addition(0,0.2,0.5,1.0 wt%)on the microstructure and mechanical properties of cast Mg-1Nd-1Ce-Zr alloy in as-cast,solution-treated and 200℃peak-aged conditions were studied.Precipitates in cast Mg-1Nd-1Ce-Zr alloy are significantly modified by the Zn addition.In the Zn-free alloy,the disk-shaped prismatic precipitates and the point-like precipitates are the main strengthening phases.When 0.2 Zn is added,the disk-shaped precipitates are refined and very fine basal precipitates form additionally.When 0.5 Zn is added,the basal precipitates become the main strengthening phase.Further increasing the Zn addition to 1.0%,only spare basal precipitates and point-like precipitates exist.The 0.5 Zn addition alloy has the highest strength at room temperature,whose yield strength,ultimate tensile strength and elongation in T6 condition are 136 MPa,237 MPa and 9%,respectively.