Effect of pulse magnetic field on solidification structure and properties of pure copper

The application of pulse magnetic field to metal solidification is an advanced technique which can remarkably refine solidification structure. In this paper, the effect of pulse magnetic field on solidification structure, mechanical properties and conductivity of pure copper was experimentally investigated. The results showed that the solidification structure transformed from coarse columnar crystal to fine globular crystal with increasing pulse voltage. Increasing pulse voltage also improved the tensile strength. However, with the increase of pulse voltage, the elongation and electrical resistivity firstly decreased, then increased when the pulse voltage beyond a critical value. Moreover, in some conditions, pulse magnetic field can simultaneously improve the conductivity and mechanical property of pure copper.     

Effect of Al on microstructure and magnetic properties of mould-cast Nd60Fe40−xAlx alloys

Mould-cast Nd₆₀Fe_40−xAl_x (x=0, 5, 10) alloys were studied to clarify the effect of Al on the structural and magnetic properties. For binary Nd₆₀Fe₄₀, the metastable hard magnetic A₁ phase forms along with the Nd₂Fe₁₇ equilibrium phase. Partial substitution of Fe by Al favours the formation of the hard magnetic metastable A₁ phase manifested by a large magnetization.     

Effect of mischmetal on the corrosion properties of Mg–5Al alloy

The effect of mischmetal (Mm) on the corrosion properties of Mg–5Al alloy was investigated by electrochemical techniques in 0.01 M NaCl solution as the alkaline condition (pH 12) and surface analyses. The electrochemical tests indicated that the pitting potential, time to pitting initiation, and charge transfer resistance of the Mg–5Al specimens increased with increasing Mm content. Surface analyses indicated that Mm promoted the formation of passive film in the absence of Mm products. In addition, the benefits of Mm addition are the refinement of the precipitates and reduction in grain size.     

Effects of high magnetic field on modification of Al-Si alloy

1INTRODUCTIONAmong Al-Si alloys,the Al-Si eutectic alloyhas the best foundry capability.The mechanicalproperties of Al-Si eutectic and hypoeutectic alloyhighly relates to the shape,size and distribution ofSi phase in eutectic structure.Coarse acicular-likeeutectic Si dissevers Al matrix badly to inducestress concentration and debase the mechanicalproperties,especially the tenacity.Modification isthe process to change the shape and size of eutecticSi,namely to change the shape of eutec…     

Effect of external stress and bias magnetic field on transformation strain of heusler alloy Ni-Mn-Ga

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｔｈｅｌａｓｔｄｅｃａｄｅｓ ,ｆｅｒｒｏｍａｇｎｅｔｉｃｓｈａｐｅｍｅｍｏｒｙａｌｌｏｙｈａｖｅｂｅｅｎａｔｔｒａｃｔｉｎｇｉｎｖｅｓｔｉｇａｔｉｏｎｓｅｍｅｒｇｅｄａｓａｎｅｗｃｌａｓｓｏｆａｃｔｉｖｅｍａｔｅｒｉａｌｓｓｈｏｗｉｎｇｖｅｒｙｌａｒｇｅｒｅｖｅｒｓｉｂｌｅｓｔｒａｉｎ ,ｓｈｏｒｔｒｅａｃｔｉｏｎｔｉｍｅ .Ａｓｆｏｒｓｕｃｈｍａｔｅｒｉａｌｓ ,Ｎｉ Ｍｎ Ｇａ ,Ｆｅ Ｐｄ ,Ｆｅ ＰｔａｎｄＣｏ Ｎｉｗｅｒｅｒｅｐｏｒｔｅｄ[19] .Ｎｉ2 ＭｎＧａ ,ａｓｔｈｅ…     

Effect of turbulent flow on electromagnetic elimination with high frequency magnetic field

1 Introduction The application of the electromagnetic body force to separate non-metallic inclusions was proposed by ALEMANY et al[1,2]. And ASAI et al have measured the migration velocity of polystyrene particles in a sodium chloride aqueous solution, in which a DC electric field and DC magnetic field were simultaneously imposed. They found that the direction of migration is opposite to the electromagnetic force and the migration velocity agrees well with the values calculated from the …     

Effect of external stress and bias magnetic field on transformation strain of heusler alloy Ni-Mn-Ca

Th influence of external field(magnetic field and stress field)on the transformation strain of Ni52.9-Mn24.4Gas22.7 single crystal were investigated and its mechanism was also discussed.When thermally martensitic transformation occurs,about 0.25% transformation strain is obtained which may be obviously enhanced to about 0.8% by a 6000 Oe magnetic bias field.However,the strain decreases by the external compress stress loaded along the strain-measured direction.When the external compress stress and bias magnetic filed are simultaneously applied,the transformation strain decreases with increasing the magnetic field.wich is related to the rearrangement of the martensite variants influenced by the external field.     

Effect of Si content on surface hardening of Al–Si alloy by shot peening treatment

The effect of Si content was investigated for Al–Si alloys (Al-7%, 11%, 18%Si) by shot peening process. The hardness increment by shot peening increased as the Si contents in Al–Si alloys increased. Finer Si particles and more dense distribution of those were observed in Al–18%Si than Al–7%Si. As Si contents of Al–Si alloys increased, grain size at the surface area of Al–Si alloy decreased. Higher hardness of Al–Si alloy with higher Si content could be attributable to more dense and refine Si particles and accelerated grain refinement during severe deformation.     

Effect of Gallium on microstructure and mechanical properties of Nb–Si eutectic alloy

In this paper, we report a significant improvement in mechanical properties of near eutectic Nb–Si alloys by addition of Gallium (Ga) and control of microstructural length scale. A comparative study of two alloys Nb-18.79 at.%Si and Nb-20.2 at.%Si–2.7 at.%Ga were carried out. The microstructure refinements were carried out by vacuum suction casting in water cooled thick copper mold. It is shown that addition of Ga suppresses Nb₃Si phase and promotes β-Nb₅Si₃ phase. The microstructural length scale and in particular eutectic spacing reduces significantly to 50–100 nm in suction cast ternary alloys. Compression test shows a strength of 2.8 ± 0.1 GPa and plasticity of 4.3 ± 0.03%. In comparison, the binary Nb-18.79 at.%Si alloy processed under identical conditions exhibit coarser length scale (300–400 nm) and brittle behavior. The fracture toughness of Ga containing suction cast alloy shows a value of 24.11 ± 0.5 MPa√m representing a major improvement for bulk Nb–Si eutectic alloy.     

Microstructure and mechanical properties of Al–Si alloy modified with Al–3P

Al–Si alloy was modified with Al–3P master alloy at 740 °C. The effects of Si content (7, 8, 9, 10 and 11 wt.%) and adding amount of alterant Al–3P (0, 0.1, 0.3, 0.6, 1.0 and 1.5 wt.%) on microstructures and tensile properties of the alloy were investigated with optical microscope (OP), Image Pro Plus 6.0, scanning electron microscope (SEM) and universal testing machine. When the content of Al–3P is 0.6 wt.%, the area fraction of primary α(Al) in the Al–Si alloy increases more compared to the unmodified alloy with an increase in Si content, which could be explained by the movement of non-equilibrium eutectic point. When the Si content is constant (Al–10Si), with the increase of Al–3P content, the increased rate in area fraction of primary α(Al) phase in the Al–10Si alloy increases first and then decreases. And when 0.6 wt.% Al–3P is added, the increase in area fraction of primary α(Al) phase is the largest. Compared to the unmodified Al–10Si alloy, the tensile strength and elongation of Al–10Si alloy increase by 2.3% and 47.0%, respectively, after being modified with 0.6 wt.% Al–3P alloy. The fracture mode of the modified Al–10Si alloy is ductile fracture.     

Fatigue properties of Al–Si casting alloy with cold sprayed Al/SiC coating

Abstract

The fatigue properties of Al–Si alloy cold sprayed Al and Al–SiC composite coatings have been studied. The specimens coated with composites reinforced with a large volume (25%) of fine SiC particles exhibited improved adhesion strength at the interface due to crater formation, and cyclic fatigue lives at room temperature more than three times those of uncoated specimens. In high temperature low cycle fatigue tests at 250°C, the pure Al coatings showed longer fatigue lives than the Al–SiC composite coatings, which is attributed to an increment in ductility at the surface retarding fatigue crack initiation.     

Effect of temperature conditions on grain refinement of Mg–Al alloy under ultrasonic field

The effects of temperature conditions on the grain refinement of a Mg–Al alloy by ultrasonic treatment were investigated. It was found the grain refinement strongly depended on the temperature. When the ultrasonic treatment was performed above the liquidus temperature, the better grain refinement was achieved in the ingot treated at 700 °C rather than at lower temperature. While for the cases of the ultrasonic treatment being ended below the liquidus temperature, the better refinement can be achieved at lower ending temperature. The undendritic structrue of UST ingots is obviously different with the dendritic structure of UMT ingots. The ultrasonic cavitation improves the nucleation temperature, resulting in greater undercooling to benefit the nucleation. The acoustic streaming accelerates the release of latent heat of solidification and shorten the time for grain growth. Both of the two factors contribute to achieve the grain refinement.     

Microwave absorbing mechanism of soft magnetic alloy Fe85Si2Al6Cr7

The powders of amorphous nanocrystalline Fe85Si2Al6Cr7 were prepared by high energy ball milling for different times, and measured by XRD and network analyzer. The results show that： 1） nanocrystalline microstructure remarkably improves the microwave permeability, and the permittivity is controlled effectively; 2） by adding proper dyeing auxiliary （such as copper phthalocyanine）, the magnetic properties of powders are improved when the particle sizes milled are excessively small.     

An investigation of the effect of structural order on magnetostriction and magnetic behavior of Fe–Ga alloy thin films

This paper reports results from a comprehensive study of Fe–Ga films fabricated over a wide range of growth conditions. Polycrystalline Fe_100?xGa_x films (14 ? x ? 32) were deposited (using three different combinations of growth parameters) on Si(1 0 0) using a co-sputtering and evaporation technique. The growth parameters (sputter power, Ga evaporation rate and chamber pressure) were used primarily to control the Fe:Ga ratio in the films. X-ray diffraction showed that all films had 〈1 1 0〉 crystallographic texture normal to the film plane. The lattice parameter increased with % Ga up to x = 22 and was independent of growth parameters. Conversion electron Mössbauer spectroscopy studies showed a predominance of the disordered A2 phase in all films. It appears that the use of vacuum deposition with appropriate parameters can effectively suppress the D0₃ ordered phase. Systematic studies of the effective magnetostriction constant as a function of composition support this conclusion. It was found that films of high effective saturation magnetostriction constant and low stress could be fabricated using low Ar pressure, irrespective of sputter power or evaporation rate, giving properties useful for application in microelectromechanical systems.     

Effect of Ni/Fe ratio of electrolyte salts on the magnetic property of electrodeposited Fe–Ni alloy

Electrodeposition of Fe–Ni thin films has been carried out on a copper substrate from simple as well as complex baths containing sulfate salts with Ni/Fe ratio of 1 : 1 and 12 : 1. Complex baths consistedeither all of ascorbic acid, citric acid and saccharine in addition to the salts viz. NiSO₄ · 7H₂O; FeSO₄ · 7H₂O; H₃BO₃ and Na₂SO₄ in simple bath. The chemical composition of the deposit was determined by an energy dispersive X-ray analyzer. Magnetic properties of the Fe–Ni films were measured by avibrating sample magnetometer (VSM). The X-ray diffraction was done on the electrodeposited thin films to determine Fe–Ni alloy phases. Magnetic properties of films were studied before and after heat treatment of the samples. It is found that the saturation magnetization decreases with increasing Ni content in the films obtained from simple baths with low Ni/Fe ratio (1 : 1) while the saturation magnetization increases with increasing Ni content obtained from complex bath with high Ni/Fe ratio (12 : 1). Among different baths with high Ni/Fe ratio of 12 : 1, the saturation magnetization of deposited film is higher deposited from a bath containing three complexing agents, namely, ascorbic acid, citric acid and saccharine than from a bath containing a single complexing agent–ascorbic acid. The ideal nature of the M _s–H (saturation magnetization vs. applied field) curve was obtained from complex baths with a high Ni/Fe ratio (12 : 1).     

Effect of neutron irradiation and postradiation annealing on the microstructure and properties of an Al–Mg–Si alloy

The effect of long-term neutron irradiation and postradiation thermal-induced aging on the microstructure and mechanical properties of an aluminum-based reactor Al–Mg–Si alloy grade SAV-1 has been studied. The material under study is the shell of an automatic fine-control rod used to control the reactivity of the core of a VVR-K research reactor. Successive 1-h annealings of specimens of the SAV-1 alloy irradiated to doses of 0.001 and 5 dpa in the temperature range of 100–550°C have been carried out. The evolution of the fine structure of the material and changes in its mechanical characteristics have been studied. The phenomenon of the acceleration of the aging of the SAV-1 alloy under the effect of a high neutron fluence at an irradiation temperature of 80°C has been observed, which involves the formation of numerous lineage (stitch) Guinier–Preston zones in the alloy. It has been shown that the strength characteristics of the SAV-1 alloy depend significantly on the degree of its radiation- and thermal-induced aging.     

Effect of magnetostatic field on microstructure of magnesium alloy ZK60

1　INTRODUCTIONNonferrousmaterialshavedisplayedmoreandmoreimportantrolesinthe 2 0 st century .Amongthesenonferrousmaterials ,magnesiumalloyisoneofthelightest practicalmaterial,butmagnesiumisametalwithastrongelectronegativity .Itsstandardelectricpotentialis - 2 .36 3V ,anditserosionresis tanceisnotgood .Becauseoftheoxidizationduringrefining ,deformationandapplication ,theadvantagesofmagnesiumalloysandtheirapplicationislimited .Asthedevelopmentoftherefiningtechnologyandad vancedformationte…