Effect Of Magnesium Addition Research Articles

Effect of Magnesium Addition and High Energy Processing on the Degradation Behavior of Iron Powder in Modified Hanks’ Solution for Bioabsorbable Implant Applications

This paper shows the results of applying a combination of high energy processing and magnesium (Mg) as an alloying element in a strategy for enhancing the degradation rate of iron (Fe) for applications in the field of non-permanent medical implants. For this purpose, Fe powder was milled with 5 wt% of Mg (Fe5Mg) and its microstructure and characterized degradation behavior. As-received Fe powder was also milled in order to distinguish between the effects due to high energy processing from those due to the presence of Mg. The powders were prepared by high energy planetary ball milling for 16 h. The results show that the initial crystallite size diminishes from >150 nm to 16 nm for Fe and 46 nm for Fe5Mg. Static degradation tests of loose powder particles were performed in Hanks’ solution. Visual inspection of the immersed powders and the X-ray diffraction (XRD) phase quantification indicate that Fe5Mg exhibited the highest degradation rate followed by milled Fe and as received Fe, in this order. The analysis of degradation products of Fe5Mg showed that they consist on magnesium ferrite and pyroaurite, which are known to present good biocompatibility and low toxicity. Differences in structural features and degradation behaviors of milled Fe and milled Fe5Mg suggest the effective dissolution of Mg in the Fe lattice. Based on the obtained results, it can be said that Fe5Mg powder would be a suitable candidate for non-permanent medical implants with a higher degradation rate than Fe.

The Effect of Magnesium Additions on Microstructural, Thermal, and Mechanical Properties of Rapidly Solidified Al-5.5wt.%Zn-x wt.%Mg (x = 1, 5) Alloys

The effect of magnesium addition on the morphological, thermal, and mechanical features of conventionally and rapidly solidified Al-5.5 wt.%Zn-x wt.%Mg (x = 1, 5) samples were examined in this work. Al-5.5wt.%Zn-x wt.%Mg (x = 1, 5) samples were produced by the conventionally solidified graphite casting and rapid solidification by the melt-spinning method. The morphological and phase structures of the alloys were shown by field emission scanning electron microscopy and x-ray diffractometry. The melting temperatures were examined by differential thermal analysis in an Argon gas environment and the stress and microhardness characteristics of the conventionally solidified and melt-spun ribbons were determined by hardness and tensile strength tests. It was observed that the content of 5 wt.%Mg allowed a radical change in the conventionally solidified alloy morphologies, such as nano-sized dot shape Al12Mg17 particles and smaller sized square shaped MgZn2 particles. Moreover, the ultimate tensile strength, yield strength, and microhardness values of the rapidly solidified Al-5.5Zn-5Mg samples increased by approximately 20%. Finally, it was observed that the microstructural and mechanical properties, such as microhardness/stress values and grain size refinement, were improved with high wheel speeds.

Formation and Evolution of Silicate Inclusions in Molten Steel by Magnesium Treatment

The effect of magnesium addition on the formation and evolution of inclusions in Mn–Si killed steel is studied by laboratory experiments and thermodynamic calculation. Samples were taken at different holding time after magnesium addition to study the transient evolution of inclusions. The morphology, composition, number and diameter of inclusions were thoroughly analyzed by SEM-EDS. The results show that four types of inclusions (MgO–SiO2–MnO liquid inclusion, MgO–SiO2–MnO complex inclusion, MgO–SiO2 and MgO solid inclusion) form with different amount of magnesium addition. Liquid inclusion of MnO–SiO2 is promptly modified to MgO–SiO2–MnO liquid inclusion with 0.0005% magnesium addition. As the amount of magnesium is increased to 0.0011%, intermediate product MgO forms immediately and then gradually transforms to MgO–SiO2 solid inclusion with holding time. While MgO solid inclusion keeps stable throughout with 0.0019% magnesium addition.

Effect of Magnesium Addition on Mechanical Properties of Al-Fly Ash Green Composite Produced Under Green Ultrasonic Vibration Process

In the present investigation an effort has been made to produce Al-Fly ash green composite using liquid state stir casting technique followed by green ultrasonic vibration such that it can improve wettability of fly-ash with aluminium by adding magnesium in the presence of argon gas. Addition of magnesium increases wettability of fly-ash particle in the molten aluminium and improves mechanical properties of Al-Fly ash green composite to a great extent. Incorporation of magnesium enhances the homogeneous allocation of fly ash particles in the pure aluminium alloy. More uniform distribution of Fly ash provides better mechanical properties. In this study, sample of Al/2 wt.% Mg/8 wt.% Fly ash provides most excellent outcome amongst all the selected composition. Microstructures show that the distribution of reinforcements is more uniform in this composition. TEM image shows proper wettability between aluminium and reinforcements. Density, cost estimation, hardness, toughness, ductility and tensile strength were also calculated to observe the result of magnesium and fly ash addition in aluminium matrix.

Effect of magnesium addition on the structural homogeneity of NiTi alloy produced by self-propagating high-temperature synthesis

Effect of magnesium addition on the structural homogeneity of NiTi alloy produced by self-propagating high-temperature synthesis

Effect of Magnesium Addition on Corrosion Resistance of Aluminum -17%Silicon Alloy

The electrochemical behavior of Al-17%Si alloy is investigated in 3.5wt% NaCl solution. Many alloys with addition of the different wt% magnesium metal of 1wt%, 2%, 3wt% ,4.5wt% ,and 9wt% were prepared by gravity die casting . The microstructures of prepared alloys were examined by optical and SEM microscopes. Corrosion behavior was investigated by using potentiostat instrument under static potentials test and corrosion current was recorded to determine corrosion resistance of all prepared samples. It was found that the addition of Mg metal improves the corrosion resistance of Al-17%Si alloy in 3.5%NaCl solution. The alloy containing 1%Mg shows less corrosion rate than the others while the alloys containing 4.5%Mg, 9%Mg content have the better pitting corrosion resistance than other alloys.

Effect of magnesium addition in low carbon steel part 2: toughness and microstructure of the simulated coarse-grained heat-affected zone

ABSTRACTA critical investigation into the role of Mg on the toughness and microstructure of coarse grain heat-affected zone (CGHAZ) in low carbon steel has been investigated. In this research, the specimens (Mg-free and Mg-added) underwent weld thermal cycle with heat input of 54, 80, and 100 kJ cm−1 at 1350°C peak temperature using a thermal simulator. The typical inclusions characteristics were characterised by means of scanning electron microscopy and equilibrium calculations. The precipitates were characterised by transmission electron microscopy and energy-dispersive spectroscopy. It is revealed that the occurrence of Mg in steel mostly exists in the form of Mg-Al-O oxide inclusions, but a few in the form of solid solution state and (Nb,Ti)(C,N)+MgO precipitates when the concentration of Mg is 0.0026%. The improvement of CGHAZ toughness is obtained when the heat input is 80 and 100 kJ cm−1. The possible reasons about the effects of Mg on the toughness of CGHAZ, including Mg-Al-O inclusions, precipitates, and soluble Mg, are discussed in detail.

Effect of magnesium addition in low-carbon steel part 1: behaviour of austenite grain growth

ABSTRACTTo reveal the effect of Mg addition on the austenite grain growth in low-carbon steel, the steels containing different Mg contents were refined with a vacuum induction furnace. First, the steels were subjected to the temperature range of 1000–1300°C for a holding time of 30 min. Moreover, using a confocal scanning laser microscope, the growth of austenite grains was investigated under isothermal holding conditions (1400°C), and the γ–α phase transformation was also identified after the samples were subjected to a cooling rate of 5°C s−1. It reveals that the grain growth is inhibited by Mg addition after increasing the temperature to 1300°C. The kinetic equations of austenite grain growth were further established by regression analysis based on the experimental results. Furthermore, a significant increase in the proportion of intra-granular ferrite takes place in 0.0026%Mg-added steel at the initial stage of γ → α with a cooling rate of 5°C s−1. This is mainly attributed to the plenty of Mg-containing inclusions, which are demonstrated to be effective nuclei for acicular ferrite, being in the Mg-added steel.

Effect of Magnesium Addition on the Cell Structure of Foams Produced From Re-melted Aluminum Alloy Scrap

Closed-cell foams were produced from re-melted aluminum alloy scrap that contained 0.13 wt pct Mg magnesium in the as-received state and higher levels after adding 1, 2, or 5 wt pct Mg. The excess Mg gave rise to the fragmentation of long oxide filaments present in the scrap alloy into smaller filaments and improved its distribution and wetting by the Al matrix. Foaming the re-melted scrap alloy containing 1, 2, and 5 wt pct Mg excess showed stability and good expansion in comparison to the scrap alloy containing 0.13 wt pct Mg only, but the cells became non-equiaxed when the Mg concentration was high (≥2 wt pct excess) due to cell wall rupture during solidification. Compressibility and energy absorption behavior were studied for scrap alloy foams containing 1 wt pct Mg excess, which is the optimum level to obtain good expansion, stability, and uniform cell size. Foams with densities in the range of 0.2 to 0.4 g cm−1 produced by holding at the foaming temperature for different times were used for the investigation. A uniform cell structure led to flatter stress plateaus, higher energy absorption efficiencies, and reduced “knockdown” in strength compared with commercial foams made by gas bubbling. The mechanical performance found is comparable to that of commercial foams made by a similar method but the expected costs are lower.

Phase Transformations in Mechanically Alloyed and Sintered Ti-XMg-22Si-11B (X = 2 and 7 at.-%at) Powders

This work reports on effect of magnesium addition on the Ti6Si2B stability in Ti-xMg-22Si-11B (x = 2 and 6 at.-%) alloys prepared by high-energy ball milling and subsequent sintering. Ball milling was conducted under Ar atmosphere in stainless steel vials and balls, 300 rpm, and a ball-to-powder weight ratio of 10:1. Following, the powders milled for 10 h were axially compacted in order to obtain cylinder samples with 6 mm diameter. To obtain the equilibrium structures the green samples were sintered at 1100°C for 4 h under Ar atmosphere. X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry were used to characterize the as-milled powders and sintered samples. Extended Ti solid solution were found in the Ti-2Mg-22Si-11B and Ti-7-Mg-Si-B powders milled for 20 min and 60 min, respectively, whereas an amorphous halo was produced on Ti-2Mg-22Si-11B powders milled for 420 min. The increase of Mg amount in the starting powder mixture has inhibited the Ti6Si2B formation in the mechanically alloyed and sintered Ti-7Mg-22Si-11B alloy.

Effect of acid leaching conditions on impurity removal from silicon doped by magnesium

The effect of magnesium addition into a commercial silicon and its leaching refining behavior is studied for producing solar grade silicon feedstock. Two different levels of Mg is added into a commercial silicon and the leaching of the produced alloys by 10% HCl solution at 60 ℃ for different durations is performed. It is shown that the microstructure of the alloy and in particular the distribution of eutectic phases is dependent on the amount of the added Mg. Moreover, the metallic impurities in silicon such as Fe, Al, Ca and Ti are mainly forming silicide particles with different compositions. These silicides are physically more detached from the primary silicon grains and their removal through chemical and physical separation in leaching is better for higher Mg additions. It is observed that the leaching is more effective for the purification of smaller silicon particles produced from each Mg-doped silicon alloy. It is shown that acid leaching by the applied method is effective to reach more than 70% of phosphorous removal. It is also shown that the purity of silicon is dependent on the total Mg removal and effectiveness of leaching on removing the Mg2Si phase.

Effect of magnesium on dispersoid strengthening of Al—Mn—Mg—Si (3xxx) alloys

The effects of magnesium addition on the dispersoid precipitation as well as mechanical properties of 3xxx alloys were investigated. The microstructures in as-cast and heat-treated conditions were evaluated by optical microscopy and transmission electron microscopy. The results reveal that Mg has a strong influence on the distribution and volume fraction of dispersoids during precipitation heat treatment. The microhardness and yield strength at ambient temperature increase with increasing Mg content. The solid solution and dispersoid strengthening mechanisms of materials after heat treatment are quantitatively analyzed. Dispersoid strengthening for the alloys is the predominant strengthening mechanism after precipitation heat treatment. An analytical model is introduced to predict the evolution of ambient-temperature yield strength.

Effect of Magnesium Additions on Composites with Al and Al – 12% Si Matrices Strengthened with B4C and Prepared by Infiltration Under Pressure

Metallographic and x-ray phase analyses are used for metal-matrix composites Al – B4C and (Al – 12% Si) – B4C with a volume fraction of 60% boron carbide prepared by infiltrating a pressed workpiece with metal under pressure. It is shown that with introduction of 1 to 4% Mg into a metal matrix composite porosity is reduced from 7 to 1%.

Effect of Magnesium Addition on Behavior of Collision and Agglomeration between Solid Inclusion Particles on H13 Steel Melts

Behavior of collision and agglomeration between solid inclusion particles MgO · Al2O3 and Al2O3 on H13 molten steel surfaces is observed in situ through a confocal scanning laser microscope (CSLM) equipped with a gold image furnace, and the attractive force between these solid inclusions is calculated by using Newton's second law. Results and analysis show that the attractive force between alumina particles in H13 steel without magnesium is stronger than that between MgO · Al2O3 particles in H13 steel containing magnesium, and the action radius of attractive force between alumina particles is larger than that between MgO · Al2O3 particles. MgO · Al2O3 particles have a much weaker tendency to collide, agglomerate, grow, and form clusters than alumina particles in H13 steel. Therefore, the collision, agglomeration and growth of inclusions, as well as the formation of clusters in H13 steel can be effectively impeded by the adding of magnesium.

Effect of magnesium addition on the structural, microstructural and electrical properties of YVO4

The synthesis of Y1-x/2MgxV1-x/2O4-δ (MgxYV) (x = 0.0–0.5) by solid state reaction technique is reported. This preparation method is compared with chemical synthesis method such as nitrate-citrate auto-combustion route. The crystal structure and the surface morphology of the samples were determined by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques, respectively. Substantial decrease in phase formation temperature was observed for combustion method. The solubility limit of Mg in YVO4 lattice was found to be low i.e., x ≤ 0.1. The temperature dependence of conductivity of MgxYV samples indicated an increase in ionic conductivity values compared to the parent YVO4 due the formation of oxygen ion vacancies produced by the incorporation of acceptor Mg cations. Combustion-synthesized MgxYV samples showed higher conductivity compared to the samples prepared by conventional solid state reaction.

Effect of magnesium addition on evolution of inclusions in Mn–Si–Al deoxidised molten steels

To reveal the effects of magnesium on the evolution of inclusions in Mn–Si–Al deoxidised steels, both thermodynamic calculations and deoxidised experiments were carried out in the present work. The samples extracted from the melts were polished and analysed by optical microscope and scanning electron microscopy (SEM). The results showed that magnesium can control the size of oxide inclusions in Mn–Si–Al deoxidised melts well. Superfluous MgO raise the melting point of the complex inclusions, and then worsen the steel castability. Therefore, the amount of Mg addition should be under control. The recommend value of [Mg] in present work is 1–3 ppm, based on thermodynamic calculations and experiments. All inclusions observed in the sample were nearly spherical. The evolution mechanisms of inclusions were discussed comprehensively, and proper models for the formation of oxide inclusions were set up. In practice, to achieve the full liquid inclusions in molten steel, the addition amount of magnesium and aluminium should be considered simultaneously.

Effect of magnesium addition on inclusions in H13 die steel

The effect of magnesium addition on the number, morphology, composition, size, and density of inclusions in H13 die steel was studied. The results show that the total oxygen content in the steel can be significantly decreased to 0.0008wt%. Al2O3 and MnS inclusions are changed into nearly spherical MgO·Al2O3 spinel and spherical MgO·MgS inclusions, respectively. The number of inclusions larger than 1 μm decreases and the number of inclusions smaller than 1 μm increases with increasing magnesium content. V(N,C) precipitates around MgO·Al2O3 and MgO·MgS inclusions during solidification of liquid steel. The densities of MgO·Al2O3 spinel inclusions are lower than that of alumina inclusions. With increasing magnesium content in the Mg-containing inclusions, the density of inclusions decreases, leading to the improvement of inclusion removal efficiency.

Effect of Magnesium Addition on Properties of Al-Based Composite Reinforced with Fine NiO Particles

Abstract An Al(Mg)-NiO composite was manufactured using combined mechanical alloying (MA) and powder consolidation methods that yielded well-consolidated and very-fine grained bulk material. Compression tests at 293 K - 773 K revealed high mechanical properties of the material. Preliminary annealing at 823 K/6 h was found to result in the flow stress reduction at 573 K - 773 K. However, the effect of preliminary annealing on the flow stress value was relatively low for Al(Mg)-NiO if comparing to similar tests performed for the Al-NiO composite. Structural observations revealed very-fine grained structure of both as-extruded and annealed Al(Mg)-NiO composites. The chemical reaction between the composite matrix and reinforcements (NiO) at sufficiently high temperatures resulted in fine grains and spinel-type particles’ development. With respect to the similarly produced Al-NiO composite, a magnesium addition was found to intensify chemical reaction between Al(Mg)-based matrix and NiO particles. As result, fine Al3Ni particles were observed in both hot-extruded material and Al(Mg)-NiO samples annealed at 823 K/6 h.

The Effect of Magnesium Addition on the Microstructure & Compressive Deformation Behavior of Al-Ca Alloy

The Al-Ca-Mg alloys containing varying amount of Mg are used to study the effect of Mg addition on their microstructure and deformation behavior at varying strain rate (0.01/s, 0.1/s, 1/s). The material is prepared using stir casting technique. The yield stress, flow stress and elastic limit are measured from the true stress-strain graph. The strain rate sensitivity and strain-hardening exponent were also determined for each material at different strain rates. The elastic limit decreases with increases in strain rate. The strain rate sensitivity m is found to be negative at a flow strain and invariant to the strain rate. Its microstructure reveals that the microstructural characteristics changes with Mg addition. The variation of microstructural features primarily leading to the variation of deformation behavior.

Effect of Magnesium Addition on the Cast Microstructure of a Kind of HSLA Steel

A new technology to obtain a fine-structured and high-toughness HAZ of HSLA steel for high heat input welding is developed using metallurgical thermodynamics, physical chemistry of metallurgy and material processing methods synthetically in this study. A kind of HSLA steel is designed in this experiment. The thermal stability second phase particles which would not be dissolved or aggregated at high temperature will be expected by means of adding magnesium into the steel in the form of Mg-Zr alloy. The effect of magnesium addition on the cast microstructure of HSLA steel was analysed. The results show that The cast microstructure is mainly consist of lamellar and acicular ferrite, a small amount of pearlite and bainite. Compared with the original steel, there are acicular ferrites presenting in the experimental steel after adding 3 wt% Mg and 5 wt% Mg, which are the microstructure that we hope to get. The acicular ferrite will have a positive impact on the mechanical properties of the subsequent rolled steel.