Magnetic and chemical properties investigation of Fe–Ni electrodeposited alloy on titanium substrate at the presence of alumina

Iron-nickel alloys have different applications in electronic systems depending on their magnetic properties. In this research, Iron-nickel alloy and its composite with Al₂O₃ particles were produced by electro wining method using a titanium cathode which is traditionally produced through a melting process (pyrometallurgy). The effect of the processing parameters on the products specification was investigated by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and alternative gradient field magnetometer (AGFM). The produced alloy could be specified as; high saturation magnetization, low coercivity, and low magnetization, and so could be classified in the soft magnetic alloys groups. The best magnetic property of the alloy was obtained at low current density with a coercivity of about 3.10 O_e. SEM images show the cauliflower-like morphology of the product. At the presence of Al₂O₃ nanoparticles in the electrolyte, a well-dispersed particles of alumina in the alloy was observed with a decrease in the magnetization and increase in the coercivity of the alloy. Also, the modified alloy with Al₂O₃ shows better corrosion resistance in NaCl solution.

     

Enhancement of Elevated-Temperature Strength in Al–Cu–Ce–Mn–Zr Cast Aluminum Alloy Through Ni Alloying

Herein, to enhance the elevated-temperature strength of heat-resistant aluminum alloys to satisfy application requirements, the effect of Ni content (0.5, 1.0, 2.0, 4.0 wt%) on the microstructures and tensile properties of Al–8.4Cu–2.3Ce–1.0Mn–0.2Zr alloy is investigated. The metallographic analysis techniques are used to quantitatively examine the microstructural changes. The skeleton-like Al₇Cu₄Ni phase is formed after the addition of Ni and its morphology is gradually transformed into a coarse reticular-like shape with Ni content increasing. However, the thermally stable Al₈CeCu₄ and Al₂₄MnCu₈Ce₃ phases disappear when Ni content exceeds 1.0%. Al–8.4Cu–2.3Ce–1.0Mn–0.2Zr–0.5Ni alloy exhibits the optimal elevated-temperature tensile performance at 400 °C, and its ultimate tensile strength, yield strength, and elongation at 400 °C reach 105, 85 MPa, and 16.5%, respectively. The optimal tensile performance is attributed to synergistic enhancing action of the thermostable Al₈CeCu₄, Al₂₄MnCu₈Ce₃, Al₁₆Cu₄Mn₂Ce, and Al₇Cu₄Ni phases at the grain boundaries and the nano-sized Al₂₀Cu₂Mn₃ and Al₂Cu precipitates inside the grains. The typical brittle fracture is dominating in the five alloys with different Ni contents at ambient temperature, but the fracture mode at 400 °C is changed from ductile fracture to ductile and brittle mixed fracture with the increase of Ni.     

Phase transformation,thermoelastic and magnetic properties of Ni50Mn30Ga20−xCux ferromagnetic shape memory alloys

Effect of addition of Cu on phase transformation temperatures, enthalpy and entropy changes, Curie temperature, magnetization saturation were investigated in Ni–Mn–Ga ferromagnetic shape memory alloy. The results show that the Ni₅₀Mn₃₀Ga_20−xCu_x alloys exhibit thermoelastic martensitic transformation. The martensitic and reverse martensitic transformation temperatures, enthalpy and entropy changes and thermal hysteresis increase with increase of Cu content. Martensite structure changes from 7 M with 0–0.5 at.% Cu to non-modulated T martensite when the content of Cu is more than 0.5 at.%. In addition, the Curie temperature almost remains unchanged at low-Cu content and subsequently decreases obviously. Magnetization saturation of alloys decrease with increasing Cu content since it is sensitive to ordered atomic arrangement.     

Optimizing the tensile properties of Al–Si–Cu–Mg 319-type alloys: Role of solution heat treatment

The work presented in this study was carried out on Al–Si–Cu–Mg 319-type alloys to investigate the role of solution heat treatment on the dissolution of copper-containing phases (CuAl₂ and Al₅Mg₈Cu₂Si₆) in 319-type alloys containing different Mg levels, to determine the optimum solution heat treatment with respect to the occurrence of incipient melting, in relation to the alloy properties. Two series of alloys were investigated: a series of experimental Al–7 wt% Si–3.5 wt% Cu alloys containing 0, 0.3, and 0.6 wt% Mg levels. The second series was based on industrial B319 alloy. The present results show that optimum combination of Mg and Sr in this study is 0.3 wt% Mg with 150 ppm Sr, viz. for the Y4S alloy. The corresponding tensile properties in the as-cast condition are 260 MPa (YS), 326 MPa (UTS), and 1.50% (%El), compared to 145 MPa (YS), 232 MPa (UTS), and 2.4% (%El) for the base alloy with no Mg. At 520 °C solution temperature, incipient melting of Al₅Mg₈Cu₂Si₆ phase and undissolved block-like Al₂Cu takes place. At the same time, the Si particles become rounder. Therefore, the tensile properties of Mg-containing alloys are controlled by the combined effects of dissolution of Al₂Cu, incipient melting of Al₅Mg₈Cu₂Si₆ phase and Al₂Cu phase, as well as the Si particle characteristics.     

合金元素对块体纳米晶Fe3Al材料磁学性能的影响

为了研究合金元素对块体纳米晶Fe3Al材料磁学性能的影响,通过铝热反应熔化法制备了纳米晶Fe3Al以及分别含Ni质量分数10%、Cr质量分数10%、Mn质量分数10%和含Ni质量分数10%-Cu质量分数2%的块体纳米晶Fe3Al.在振动样品磁强计(VSM)上测得合金的磁滞回线,分析其磁性能,采用X射线衍射仪进行结构分析和平均晶粒尺寸计算.结果表明:各样品的磁滞回线呈倾斜状且狭长,磁滞损耗很小;含Ni质量分数10%的样品饱和磁化强度Ms较大,剩余磁化强度Mr和矫顽力Hc较其他样品最小,具有较好的软磁性能;添加合金元素后几种材料的晶粒尺寸变小,磁性能有较大变化,合金元素对纳米晶Fe3Al块体材料的磁性能影响明显.     

Combustion synthesis of ferromagnetic Al2O3-based cermets in thermal explosion mode

The ferromagnetic Al₂O₃-based cermets with different ratios of Co and Co–50Ni alloys were successfully prepared by combustion synthesis in thermal explosion (TE) mode. The reaction process, microstructure, and magnetic property of cermets were investigated. The relative density of cermets can be over 95% via uniaxial loading at the time of ignition when the cermets are hot and ductile. In Al₂O₃–Co cermets, β-Co and α-Co co-exist at room temperature with average size of less than 10 μm and disperse homogeneously in the matrix, while in Al₂O₃–(Co–50Ni) cermets, the network-like Co–50Ni alloy can infiltrate into the boundary gaps of Al₂O₃ particles. The ferromagnetic Co and Co–50Ni alloys are responsible of the magnetic properties of Al₂O₃-based cermets. The saturation magnetization strongly depends on the magnetic characteristics and ratios of ferromagnetic phases. Al₂O₃–(Co–50Ni) cermets have soft magnetic properties with high magnetic susceptibility and low coercive force.     

Annealing Effect on Structural and Magnetic Properties of Cu2MnAl Heusler Alloy Films

Cu₂MnAl Heusler alloy films were grown on MgO (001) substrates by using the ion beam sputtering technique. The films were post-annealed at varying temperatures in order to investigate the influence of annealing on crystal structure and magnetic properties. The structural properties of Cu₂MnAl films have been investigated by using x-ray diffraction (XRD) and magnetic properties have been investigated by both vibrating sample magnetometer (VSM) and ferromagnetic resonance (FMR) techniques. The experimental data indicates that the crystal structure of the films strongly depends on the annealing temperature. When the films were annealed at 200?°C, the saturation magnetization (M _s =250?emu/cm³) achieved its maximum and the coercive field (H _c ??7?Oe) reached its minimum with B2 ordered structure. In addition, FMR results have revealed that the Cu₂MnAl film annealed 200?°C has the highest effective magnetization. The combination of structural and magnetic characterization indicates that the optimum growth temperature is 200?°C for the Cu₂MnAl Heusler alloy films on MgO substrates.     

The effect of Copper alloying additions on the crystallization of an amorphous Fe–Si–B alloy

The effect of Cu alloying additions on the crystallization of Fe–Si–B alloy was studied. The selected alloys compositions are Fe_77.5Si_13.5B₉ and Fe_76.5Si_13.5B₉Cu₁. By comparing their crystallization temperatures, activation energy of crystallization, phase formation and microstructural evolution after heat treatment, the effect of Cu alloying additions was determined. It was found that Cu alloying additions reduced the crystallization temperature as well as the activation energy of the crystallization. Although the phases formed in both alloys were Fe₃Si and Fe₃B phases the microstructures were dramatically different: a dendritic microstructure was observed in the case of the Fe–Si–B alloy, while spheriodal crystals around 100 nm in size were observed in the case of the Fe–Si–B–Cu alloy. Cu alloying addition increased the saturation magnetization during primary crystallization whereas it decreased the saturation magnetization after secondary crystallization began. Interestingly, for both alloys the same trends of the magnetization and coercivity measurements were observed except that the extent of the changes were higher in the case of the Fe–Si–B–Cu alloy than that of the Fe–Si–B alloy.     

Effect of transition metal (TM) on the crystallization and the magnetic properties of Fe<Subscript>62</Subscript>Co<Subscript>10</Subscript>Si<Subscript>10</Subscript>B<Subscript>13</Subscript>Nb<Subscript>4</Subscript>TM<Subscript>1 </Subscript>melt-spun ribbons

Crystallization and magnetic behavior of melt-spun Fe₆₂Co₁₀Si₁₀B₁₃Nb₄TM₁ amorphous ribbon where TM = Ni, Cr, V, Pd, Pt, Ti, Ta and Zr were examined. The alloy with Pt as transition metal showed the lowest crystallization temperature of 823 K among the studied alloys. Significant increase in crystallization temperature was observed when the atomic radius of the substituted transition metal was varied from that of Pt. High Curie temperature and high saturation magnetization were recognized for the alloys containing Pd, Pt or Ti. The amorphous alloys except the alloys containing Ti or V showed good soft magnetic properties.     

Enhanced mechanical properties of Al–Si–Cu–Mn–Fe alloys at elevated temperatures through grain refinement and dispersoid strengthening

The effect of Ti content on the microstructure and mechanical properties of heat-treated Al–Si–Cu–Mn–Fe alloys was investigated. It was found that the mechanical properties increased with the increase of Ti content. This was attributed to the refinement of grain size, the increased amount of T (Al₂₀Cu₂Mn₃), the α-Fe (Al₁₅(FeMn)₃(CuSi)₂) precipitated particles, and the decrease in Al₂Cu. At an elevated temperature of 300°C, the heat-treated Al–Si–Cu–Mn–Fe alloy with 0.5% Ti demonstrated the best mechanical properties, which are superior to those of commercial aluminium alloys. The yield strength contribution at 300°C was quantitatively evaluated based on the dispersoid, solid solution, and matrix contributions. It was confirmed that the main strengthening mechanism in the experimental alloys was the dispersoid strengthening.     

The effects of carbon on the magnetic properties of nanocrystalline Fe-based alloys

We investigate the magnetic properties of nanocrystalline Fe_73.5Cu₁M₃Si_13.5B₉ (M=Nb or Mo) alloys when C is substituted for B up to 2 at%. It is found that the permeability and coercivity deteriorate with the content of C in the case of both M=Nb and Mo. The saturation magnetization also deteriorates as C is substituted for B in the case of M=Mo but it improves linearly with the C content in the case of M=Nb. This increase in the saturation magnetization of the Fe-Cu-Nb-Si-B alloy with C addition can provide an opportunity to overcome one of the main disadvantages, low magnetic flux density, of the alloy. In the latter part of the work we also investigate the magnetic properties of Fe_76.5–y Cu₁Nb_y (Si_0.5B_0.4C_0.1)_22.5 (0y3) alloys, particular emphasis being given to the role of Nb in the presence of C. It is found that C may help Nb to suppress the growth of -Fe grains in the alloy.     

The excellent soft magnetic properties and corrosion behaviour of nanocrystalline FePCCu alloys

The effects of the addition of Cu on the crystallisation behaviour, soft magnetic properties, and corrosion behaviour of Fe_84-xP₉C₇Cu_x (x = 0–1.15) alloys were investigated. The experimental results demonstrate that the glass-forming ability of this alloy was improved and the soft magnetic properties of the alloy system were enhanced by proper Cu addition. FePCCu nanocrystalline alloys with a dispersed α-Fe phase were obtained by appropriately annealing the melt-spun ribbons at 693 K for 2 min. The Fe_83.25P₉C₇Cu_0.75 nanocrystalline alloy exhibited a high saturation magnetic flux density, B _s , of 1.64 T; a low coercivity, H _c , of 3.9 A/m; and a high effective permeability, μ _e , of 21,000 at 1 kHz. These characteristics are superior to corresponding properties of FePC alloys. Furthermore, the corrosion resistance of this nanocrystalline alloy increases when elevating the annealing temperature and was confirmed to be improved with respect to the corresponding amorphous alloy. These results indicate that this alloy is a promising soft magnetic material.     

Effect of Cu addition on microstructures and tensile properties of high-pressure die-casting Al-5.5Mg-0.7Mn alloy

In this study, Cu was added into the high-pressure die-casting Al-5.5Mg-0.7Mn (wt%) alloy to improve the tensile properties. The effects of Cu addition on the microstructures, mechanical properties of the Al-5.5Mg-0.7Mn alloys under both as-cast and T5 treatment conditions have been investigated. Additions of 0.5 wt%, 0.8 wt% and 1.5 wt% Cu can lead to the formation of irregular-shaped Al₂CuMg particles distributed along the grain boundaries in the as-cast alloys. Furthermore, the rest of Cu can dissolve into the matrixes. The lath-shaped Al₂CuMg precipitates with a size of 15–20 nm × 2–4 nm were generated in the T5-treated Al-5.5Mg-0.7Mn-xCu (x = 0.5, 0.8, 1.5 wt%) alloys. The room temperature tensile and yield strengths of alloys increase with increasing the content of Cu. Increasing Cu content results in more Al₂CuMg phase formation along the grain boundaries, which causes more cracks during tensile deformation and lower ductility. Al-5.5Mg-0.7Mn-0.8Cu alloy exhibits excellent comprehensive tensile properties under both as-cast and T5-treated conditions. The yield strength of 179 MPa, the ultimate tensile strength of 303 MPa and the elongation of 8.7% were achieved in the as-cast Al-5.5Mg-0.7Mn-0.8Cu alloy, while the yield strength significantly was improved to 198 MPa after T5 treatment.     

A TEM study on the microstructure of rapidly solidified Cu-Y alloys

The microstructure of rapidly solidified copper-yttrium alloys was studied by TEM. For the near-eutectic alloys, the following observations were made: melt-spun Cu-12.5 wt% Y whiskers showed a very fine eutectic of f.c.c. copper and hexagonal Cu₅Y plus isolated areas of a new metastable orthorhombic phase, Cu₉Y; melt-spun Cu-51.1 wt% Y whiskers contained an amorphous matrix plus precipitates of the equilibrium phase orthorhombic Cu₂Y. For far-from-eutectic alloys, glass formation was detected in the melt-spun whiskers of Cu-25.0 wt% Y alloy, while the melt-spun Cu-18.9 wt% Y whiskers showed a fine-grained single phase Cu₅Y, an easily formed metastable phase, and melt-spun Cu-41.6 wt% Y showed an ultrafine single phase Cu₂Y, an equilibrium orthorhombic phase.     

Devitrification of rapidly quenched Al-Cu-Ti amorphous alloys

X-ray diffraction, transmission electron microscopy and differential scanning calorimetry were carried out to study the transformation from amorphous to icosahedral/crystalline phases in the rapidly quenched Al₅₀Cu₄₅Ti₅ and Al₄₅Cu₄₅Ti₁₀ alloys. In the present investigation, we have studied the formation and stability of amorphous phase in Al₅₀Cu₄₅Ti₅and Al₄₅Cu₄₅Ti₁₀ rapidly quenched alloys. The DSC curve shows a broad complex type of exothermic overlapping peaks (288- 550†C) for Al₅₀Cu₄₅Ti₅ and a well defined peak around 373†C for Al₄₅Cu₄₅Ti₁₀ alloy. In the case of Al₅₀Cu₄₅Ti₅ alloy amorphous to icosahedral phase transformation has been observed after annealing at 280†C for 73 h. Large dendritic growth of icosahedral phase along with α-Al phase has been found. Annealing of Al₅₀Cu₄₅Ti₅ alloy at 400†C for 8 h results in formation of Al₃Ti type phase. Al₄₅Cu₄₅Ti₁₀ amorphous alloy is more stable in comparison to Al₅₀Cu₄₅Ti₅ alloy and after annealing at 400†C for 8 h it also transforms to Al₃Ti type phase. However, this alloy does not show amorphous to icosahedral phase transformation.     

Ferromagnetic properties of the K2Cu1−xMnxF4 system (0 ⩽ x ⩽ 0.20)

The K₂Cu_1?xMn_xF₄ phase has been studied by magnetic X-ray and neutron diffraction measurements. For 0 ? x ? 0.20 the material is ferromagnetic with a slight decrease of the Curie temperature with increasing x. The magnetization also decreases with rising x due to antiferromagnetic couplings between Mn²⁺ and Cu²⁺ ions.     

Microstructure,tensile properties and creep behavior of Al-12Si-3.5Cu-2Ni-0.8Mg alloy produced by different casting technologies

The relationship between the as-cast microstructure and mechanical properties of the Al-12Si-3.5Cu-2Ni-0.8Mg alloys produced by permanent mold casting (PMC) and high pressure die casting (HPDC) is investigated. The alloys in both PMC and HPDC consist of Al, Si, Al₅Cu₂Mg₈Si₆, Al₃CuNi, and Al₇Cu₄Ni phase. However, the microstructure of the HPDC alloy is significantly refined. Compared to the PMC alloy, the ultimate tensile strength of the HPDC alloy is significantly increased from 244 MPa to 310 MPa, while the elongation shows a reverse trend at room temperature. At low stress and temperature range, slight variations of stress exponent and activation energy indicate that the minimum creep rate is controlled by the grain boundary creep. Then the minimum creep rate is higher for the specimen with the smaller grain size, where grain boundary creep is the dominant creep mechanism. At high stress region, the stress exponent for the PMC alloy and HPDC alloy is 5.18 and 3.07, respectively. The different stress exponents and activation energies measured at high stress and high temperature range indicates that the creep mechanism varies with the casting technologies.     

The Effects of Casting Temperature on the Glass Formation of Zr‐Based Metallic Glasses

The glass1‐forming ability of two alloys, Zr_64.9Al_7.9Ni_10.7Cu_16.5 and Zr₄₇Cu_37.5Ag_7.5Al₈, prepared by arc‐melting a mixture of Zr, Cu, Al, Ni and Ag elements is studied as a function of casting temperature. Other processing parameters such as the alloy melt mass, and the vacuum and injection pressures during the copper‐mold‐casting process are kept constant so just the influence of the casting temperature is considered. The casting temperature determines the characteristics of the liquid melt and the cooling rate. The glass‐forming ability is discussed in terms of dissipation of pre‐exiting, metastable local‐ordering clusters that act as nucleation sites promoting crystallization, the cooling rate at high casting temperatures, and the presence of oxygen in the alloys, which is increased at high casting temperatures. It is found that the glass‐forming ranges of alloys shrink as the glass‐forming size approaches a critical value. The optimum temperatures are around 1450 K and 1550 K for Zr_64.9Al_7.9Ni_10.7Cu_16.5 and Zr₄₇Cu_37.5Ag_7.5Al₈ alloys respectively. The alloys were studied by XRD, TEM, oxygen‐level determination, and DSC.     

The influence of Al content on glass forming ability and magnetic properties of high Ms nanocrystalline FeSiBPCuAl alloy

Al content on the influence of glass forming ability and magnetic properties of nanocrystalline (Fe_83.3Si₄B₈P₄Cu_0.7)_100 − xAl_x (x = 0 ∼ 1.25 at.%) alloy was investigated in our work. Experimental results show that addition of 0.5 at.% Al is effective in improving the glass forming ability of Al-free alloy and thus amorphous precursor prepared by industry-grade raw materials can be obtained. Meanwhile, the addition of Al is beneficial in decreasing coercive force and maintaining high saturation magnetization above 180 emu/g, which makes Fe-Si-B-P-Cu-Al alloy a promising soft magnetic material in potential applications.     

The low temperature magnetic properties of austenitic Fe---Cr---Ni alloys. 3. The effect of chromium concentration in Fe---Cr-17wt% Ni alloys

The magnetic properties of ternary Fe---Cr---Ni alloys containing 17 wt% Ni and 18–24% Cr have been studied over a range of temperature from 4.2–35 K by both ac and dc techniques in fields from 5 Am⁻¹ − 6 MA m⁻¹. At room temperature, the matrix of all the alloys was the paramagnetic fcc austenite phase (with an unavoidable 0.1 – 0.5 wt% δ ferrite) and on cooling all the alloys showed distinct peaks in ac susceptibility, though equivalent peaks in dc susceptibility were only observed at low fields in the alloy containing 18 wt% Cr. An analysis of the magnetization/field/temperature results showed that all the alloys were superparamagnetic at low temperature, due to the formation of ferromagnetic clusters in the disordered antiferromagnetic matrix, and that the chromium atoms make no measureable contribution to the magnetization of these clusters. Appropriate susceptibility values are tabulated for use as design data.