High-frequency Induction Melting Research Articles

Effects of Ni addition on wettability and interfacial microstructure of Sn-0.7Cu-xNi solder alloy

Purpose This paper aims to study the effect of different Ni content on the microstructure and properties of Sn-0.7Cu alloy. Then, the spreading area, wetting angle, interface layer thickness and microstructure of the soldering interface was observed and analyzed at different soldering temperatures and times. Design/methodology/approach Sn-0.7Cu-xNi solder alloy was prepared by a high-frequency induction melting furnace. Then Sn-0.7Cu-xNi alloy was soldered on a Cu substrate at different soldering temperatures and times. Findings It was found that Ni made the intermetallic compounds in the Sn-0.7Cu solder alloy gradually aggregate and coarsen, and the microstructure was refined. The phase compositions of the solder alloy are mainly composed of the ß-Sn phase and a few intermetallic compounds, Cu6Sn5 + (Cu, Ni)6Sn5. The maximum value of 12.1 HV is reached when the Ni content is 0.1 Wt.%. When the Ni content is 0.5 Wt.%, the wettability of the solder alloy increases by about 15%, the interface thickness increases by about 8.9% and the scallop-like structure is the most refined. When the soldering time is 10 min and the soldering temperature is 280 °C, the wettability of Sn-0.7Cu-0.2Ni is the best. Originality/value It is groundbreaking to combine the change in soldering interface with the soldering industry. The effects of different soldering temperatures and times on the Sn-0.7Cu-xNi alloy were studied. Under the same conditions, Sn-0.7Cu-0.2Ni exhibits better wettability and more stable solder joint stability.

Mechanical Alloying Synthesis of AB3 Zirconium Substituted Intermetallic

Abstract: Several ternary RareEarth-Magnesium-Nickel intermetallics (RE-Mg-Ni) emerged in last decade for their specific hydrogen storage capability. Nickel is now considered among strategic metals with recurrent rising price, Magnesium although its good gravimetric facility suffers from frequent oxidation or irreversible poisoning. Zirconium alloys are recognized for their improved anti-corrosion properties with enhanced wear resistance for high temperature machinability in industrial applications or energy research purposes. We proposed in this paper double substitution possibility replacing Magnesium and reducing Nickel charge. We developed new generation of quaternary Zirconium-AB3 intermetallic LaZr2Ni5Al4 using mechanical alloying method. Two binary raw materials are involved in this alloying reaction, the first is LaNi5 and the second is ZrAl2 (Laves phase C14) and both precursors are achieved quasi-quantitively using high frequency induction melting. The final target AB3 compound crystallizes in Trigonal system with space group R-3m (166) and following experimental conditions (Fritsch P7, Ω = 450 rpm) an acceptable synthesis yield (>80%) is obtained starting from 20 hours mechanical alloying. Rietveld refinement is performed to have real matrix parameters and AB3 powder surface is analyzed using Scanning Electron Microscopy.

Effect of Y content on the hydrogen storage properties of ball-milled Mg2.4-xYxNi (x = 0.05, 0.1, 0.15, 0.2) alloys

Metal hydride hydrogen storage is currently the fastest growing and most promising method of hydrogen storage. In this paper, the Mg2.4-xYxNi (x = 0.05, 0.1, 0.15, 0.2) alloys were first melted by vacuum high-frequency induction melting furnace. Subsequently the alloy ingots were mechanically crushed and mechanically ball milled for the same time. And the microstructure and gaseous hydrogen storage properties of the ball-milled alloy were characterized thoroughly by varying the content of rare earth element Y. The results showed that the main phase of the alloy is the Mg2Ni phase, followed by the Ni3Y phase and a small amount of the Mg phase and MgNi2 phase. And the diffraction peaks of the Ni3Y phase are obviously enhanced with the increase of Y content, demonstrating that the exchange of Y for Mg promotes the formation of the Ni3Y phase, but the intermetallic compound Ni3Y phase was consistently present as a chemically inert material regardless of hydrogen absorption/desorption. Based on the hydrogen storage properties, the hydrogen storage alloys with different Y contents can be fully activated after one hydrogen absorption/desorption cycle, and the gestation period of the alloys with different Y contents showed a trend of decreasing and then increasing. For alloys with different Y contents, the Mg2.3Y0.1Ni alloy demands the shortest time for the initial activation of hydrogen absorption. And when the temperature is 573 K, the time taken to absorb 90% of the hydrogen capacity was 8 min, 6 min, 8 min and 12 min, and the time taken to release 90% of the hydrogen capacity was 4.6 min, 3.4 min, 5 min and 6 min for alloys with different Y contents, respectively. And the maximum values of hydrogen absorption/desorption saturation rate of Mg2.3Y0.1Ni alloy have reached 80.17% and 96.02%, respectively. The activation energy of hydrogen release of the alloys decreases from 123.9 kJ/mol to 113.1 kJ/mol. In contrast to the kinetic properties, there is no significant difference in the enthalpy and entropy changes for different Y contents, indicating that the addition of rare earth element Y has minimal effect on the thermodynamic properties of the alloy.

Wear Evaluation of Copper-Nickel-Aluminum Alloys under Extreme Conditions

Cu-Ni-Al alloys at different concentrations were obtained using a high frequency induction melting unit, keeping a balance in the nominal compositions. Light alloys are important to be used in industrial applications. Aluminum additions result in a positive hardness increment of the ternary alloys in comparison with the binary Cu-Ni alloys. Generalized wear mechanisms of the alloys with low aluminum content are basically type abrasive, while samples with 5 and 10 at.% Al present an oxidative-adhesive wear mechanism. Wear results have indicated that aluminum addition affects positively the wear resistance, mainly in samples with high aluminum content product of the creation during the test of different oxides corresponding to the elements present in the alloys.

Numerical simulation and experimental study on production of high-speed steel powder by high-frequency induction melting gas atomization

A new method (electrode induction gas atomization, EIGA) of producing high-speed steel powder was preliminarily studied by a combination of numerical simulation and experiment. Based on COMSOL Multiphysics® software, the effect of various parameters including coil angle, output frequency and power of the electrical source on flux density, induced current, temperature field and phase field was simulated. Meanwhile, the experiment was carried out on the EIGA device to produce high-speed steel powder. The results of FEM simulation indicate that when the coil angle is 30°, there is the highest thermal efficiency on the electrode cone, and the induced current and temperature will increase as the output frequency and power of the electrical source increase. In addition, the powder experimentally obtained by the EIGA method exhibits good particle sphericity regardless of the size, with a median diameter (D50) of 71.4 μm and a low oxygen content of 81 μg/g. The phase composition of the powder is mainly composed of γ-Fe and α-Fe structures and MC-type carbides. Due to the faster cooling rate, a solidification microstructure consists of fine cellular crystals and dendrites, and no coarse eutectic carbide network is observed, also confirmed by EDX elemental mapping.

The microstructure, melting properties and wettability of Sn–3.5Ag–0.7Cu–xIn lead-free solder alloys

ABSTRACT In this work, Sn–3.5Ag–0.7Cu-xIn (SAC357-xIn) solder alloys were prepared using a high-frequency induction melting furnace and then treated under air cooling and water quenching, respectively. The evolution of the microstructure of the Sn–3.5Ag–0.7Cu–xIn lead-free solder alloys under the addition of indium and its effects on melting point, hardness and wettability were investigated. The results show that the addition of indium can remarkably affect the microstructures and melting properties of SAC357 alloys. When the content of indium increases from 0 to 5 wt.%, indium is conducive to the formation and growth of Ag3(Sn, In) and Cu6(Sn, In)5. The intermetallic compounds (IMCs) of In4Ag9 are first detected in the microstructure of SAC357-5In alloy. When the content of indium is 20 wt.%, β-Sn phases disappear and In0.2Sn0.8 IMCs become the main phase. With the cooling rate increasing, the phase compositions of as-prepared alloys are almost not changed, but the solidification structures obviously refine. Meanwhile, the melting temperatures of as-prepared alloys decrease and the microhardness values of the alloys increase. SAC357-20In solder alloy prepared by water quenching obtains the lowest melting temperature of 186.2°C and the maximum spreading rate of 2.71 cm2·g−1 at the soldering temperature of 280°C.

Effect of iron on the composition and structure of corrosion product film formed in 70/30 copper-nickel alloy

PurposeThis study aims to investigate the effect of changes in iron content in 70/30 copper–nickel alloy on the corrosion process.Design/methodology/approach70Copper–30Nickel-xFe-1Mn (x = 0.4,0.6,0.8,1.0 Wt.%) alloy were prepared by the high frequency induction melting furnace. The scanning electron microscope, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy were used to analyze the morphology and component of the corrosion product film.FindingsThe results show that the corrosion resistance of 70/30 copper–nickel alloy added with 1.0%Fe is the best, and the film is divided into inner dense Cu2O composite film and outer hydration loose layer; XRD showed that after adding 1.0% Fe, the content of Cu2(OH)3Cl in the corrosion product film was significantly reduced, while the content of Cu2O remained unchanged; XPS showed that nickel accumulates in the inner layer of corrosion product film; the stage growth mode of the film, the role of nickel in it and the enrichment mechanism of iron in the inner film were summarized and discussed.Originality/valueThe changes in the composition and structure of the corrosion product film caused by the iron content are revealed, and the mechanism of the difference in corrosion resistance is discussed.

Development and Characterization of Al-15%Mo Binary Alloys

In this work, a binary Al-Mo alloy was made from aluminum and molybdenum elementary powder. The carefully homogenized samples were mechanically compacted to obtain a pastille of circular cross section (Φ=15 mm X 10 mm) under a load of 10 tons. Subsequently, the Al-Mo sample was melted in a high-frequency induction melting furnace. The resulting sample was polished and etched with a Keller reagent.The sample was subjected to metallographic observation on an optical and scanning electron microscope. An EDS analysis was performed on the different areas of the microstructure. A diffraction X-ray characterization was also performed in order to identify the different existing phases. This study showed that the studied alloy presents a microstructure with needle-like and plate-like precipitations of different sizes homogeneously distributed and randomly oriented. The EDS microanalysis showed the presence of the Al-5Mo phase and an alpha aluminum matrix with a proportion of molybdenum. X-ray diffraction revealed the presence of several AL-Mo phases’ namely alpha aluminum, molybdenum, Al12Mo, Al8Mo3 and Al3Mo.

Exploration of the microstructures of two series of chromium-rich Mn-based alloys elaborated by casting

Manganese is a rather abundant element on earth and alloys based on it may be unexpensive. Alloyed with chromium for corrosion resistance and with carbon and a strong carbide-former element Mn can be the base of new metallic materials with interesting properties. In this work it is aimed to try elaborating Mn-based alloys by foundry and, in case of successful results, to explore the obtained microstructures. Two series were considered, a first one of the Mn – 25wt.%Cr basis with increasing amount in carbon, and a second one with addition of both carbon and tantalum addition. These seven alloys were synthesized by high frequency induction melting and their microstructures were examined using electron microscopy. Thermodynamic calculations were carried out to better understand the microstructure formation. Results show that a double-phased matrix composed of two intermetallic compounds was obtained for all alloys, as well as chromium or tantalum carbides as soon as the carbon content was high enough. Cutting was hard and led to microcracks revealing lacks in toughness. The hardness is very high. It is concluded that the elaboration of such alloys by foundry pose some problems which must be solved, but is possible. The high hardness can be interesting for some applications but the toughness is to be improved. Outlooks of this work are the characterization of the corrosion behavior of these alloys and of their mechanical properties.

Microstructure analysis of Al2O3/Er3Al5O12/ZrO2 DSECs prepared using high-frequency zone melting method

The microstructure of directionally solidified eutectic ceramics (DSECs) is mainly determined by the eutectic growth mode, properties of each phase, and solidification processing parameters. The Al2O3/Er3Al5O12(EAG)/ZrO2 DSECs were prepared using high-frequency induction melting, and their phase components, and microstructures were investigated. The results indicated that the samples were composed only of Al2O3, EAG, and ZrO2 phases. As an solidification rate increased from 5 to 500 mm/h, the microstructure was refined, and the distribution of the eutectic phases changed. This could be explained by the relationship between the undercooling, the growth rate and the melting entropy. The regular microstructure appeared in the samples prepared at low growth rate and it exhibited the form of triangles or squares. A polygonal colony structure was found in the DSECs obtained at 50 mm/h, which was related to the non-uniformed distribution of temperature fields near the solid-liquid interface. Furthermore, both of the internal microcrack and amorphous structure were identified in the rapidly solidified samples prepared at 500 mm/h.

Crystal Structures and Electrochemical Properties of R1.5Ca1.5MgNi14(R=Nd, Gd and Er) Hydrogen Storage Alloys

Ca3MgNi14, Nd1.5Ca1.5MgNi14, Gd1.5Ca1.5MgNi14 and Er1.5Ca1.5MgNi14 alloys were prepared by high frequency induction melting and sintering. Characterization and analysis were performed by X-ray diffraction/Rietveld full-spectrum fitting, gaseous P-C-T hydrogen storage test and electrochemical properties tests. It can be found that all alloys consist of Gd2Co7-type 3R phase and Ce2Ni7-type 2H phase. Although the hydrogen storage capacities of Nd1.5Ca1.5MgNi14, Gd1.5Ca1.5MgNi14 and Er1.5Ca1.5MgNi14 decrease to some extent compared to that of Ca3MgNi14, their equilibrium pressures for absorption and desorption increase markedly. Moreover, R1.5Ca1.5MgNi14 alloys have better cycling stabilities and high-rate discharge(HRD) properties as compared to Ca3MgNi14. The hydrogen diffusion in alloy electrodes is the main factor to influence the HRD performance.

The superior hydrogen-generation performance of multi-component Al alloys by the hydrolysis reaction

To obtain Al alloys possessing the excellent hydrogen-generation performance with high efficiency/low cost via the hydrolysis reaction of aluminum with water, a series of as-cast Al alloys (∼10 g) alloying by 13 kinds of Ga-based low melting point alloys with different contents were prepared by the high frequency induction melting method under a high purity argon atmosphere. The effect of the content and composition of the low melting point alloys on the hydrogen-production property of Al alloys ingots with the tap water was systematically investigated. The relationship among the hydrogen production performance, the microstructure, and the phase constituents of these Al alloys was investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy disperse spectroscopy and differential scanning calorimeter (DSC). Compared with conventional activated Al alloys powders prepared by the ball-milling method, the as-cast bulk Al alloys show the same excellent properties of hydrogen production, i.e., the high hydrogen-generation ratio but slower and more persistent hydrogen generation rate. The preparation method of Al-alloy ingots is simple, convenient, low preparation cost and high efficient, compared with the ball-milling method, which shows the significant industrial application value and prospect. Besides, the activation mechanism of the Al-water reaction dynamics was revealed on the basis of the analysis of the microstructure, phase composition and related literature.

Microstructures and hardness of model niobium-based chromium-rich cast alloys

Niobium is a candidate base for new alloys devoted to applications at especially elevated temperatures. Elaborating and shaping niobium-based alloys by conventional foundry may lead to mechanically interesting microstructures. In this work a series of charges constituted of pure elements were subjected to high frequency induction melting in cold crucible to try obtaining cast highly refractory Nb-xCr and Nb-xCr-0.4 wt.%C alloys (x=27, 34 and 37 wt.%). Melting and solidification were successfully achieved. The as-cast microstructures of the obtained alloys were characterized by electron microscopy and X-ray diffraction and their hardness were specified by Vickers macro-indentation. The obtained as-cast microstructures are composed of a body centered cubic (bcc) niobium dendritic matrix and of an interdendritic eutectic compound involving the bcc Nb phase and a NbCr2 Laves phase. The obtained alloys are hard to cut and particularly brittle at room temperature. Hardness is of a high level (higher than 600Hv) and is directly driven by the chromium content or the amount of {bcc Nb – NbCr2} eutectic compound. Adding 0.4 wt.% of carbon did not lead to carbides but tends to increase hardness.

Effect of Yttrium on the Microstructure and Properties of Pt-Ir Electrical Contact Materials

The Pt-10Ir and Pt-10Ir-1Y were prepared by high frequency induction melting, then the samples were obtained by powder metallurgy, hot extrusion and drawing. The influence of Y addition on microstructure and electrical contact properties of Pt-10Ir alloy has been investigated by using optical microscopy, SEM, electronic balance and the contact material test system. The results show that the addition of Y leads to the micro-structural refinement and directional change of material transfer, but has almost no influence on erosion morphology.

Preparation and Characterization of CuFe Alloy Ribbons

Abstract Cu-Fe master alloys with different contents of Fe were first fabricated by rapid solidification adopting high frequency induction melting. Based on the study on microstructure and the properties of Cu-Fe alloys, the quenched Cu-Fe alloy thin ribbons were prepared by a single roller melt spinning method, and the microstructures and the phase compositions of these ribbons were studied. The results show that the amount of Fe-rich dendrites increases and the dendrites are coarsened with the increase of Fe content in the range of 2 wt%∼10 wt%. The electric conductivity decreases and the hardness increases with the increase of Fe content in CuFe master alloys. The higher microhardness of Cu-rich matrix can be obtained when the content of Fe is 8.0 wt%. The grain sizes of Cu-Fe alloy ribbons are very fine. From the roll surface to the free surface, the grain size tends to be coarser along thin section due to the different solidification rates. The X-ray diffraction patterns of Cu-Fe melt-spun ribbons show that there are only Cu diffraction peaks, which become low, broad and offset to the lower degree with the increase of Fe content. The micrograph and the chemical compositions of Cu-6.0wt%Fe ribbons were characterized by SEM. The results indicate that Fe is dissolved in Cu, and the CuFe solid solution is formed.

Effects of Mg on the structures and cycling properties of the LaNi3.8 hydrogen storage alloy for negative electrode in Ni/MH battery

The LaNi3.8-type LaNi3.8 and La0.8Mg0.2Ni3.8 hydrogen storage alloys were prepared by high frequency induction melting (HFIM) under helium atmosphere followed by annealing treatment. Either alloy mainly consists of a rhombohedral Ce5Co19-type phase (R-3m) and a hexagonal Pr5Co19-type (P63/mmc) phase. The unit cell volume of either Ce5Co19-type or Pr5Co19-type phase in the La0.8Mg0.2Ni3.8 alloy is smaller than that in LaNi3.8. The Mg-containing La0.8Mg0.2Ni3.8 alloy has a lower absorption/desorption plateau, smaller hysteresis and a higher hydrogen storage capacity than those of LaNi3.8. The La0.8Mg0.2Ni3.8 alloy electrode shows an excellent activation capability and a higher discharge capacity (373.1mAhg−1) than those of the LaNi3.8 alloy electrode (184.0mAhg−1). The capacity decay rate of the La0.8Mg0.2Ni3.8 alloy electrode (0.88mAh (gcycle)−1) is much lower than that of the LaNi3.8 alloy electrode (1.32mAh (gcycle)−1), which is attributed to that the addition of Mg suppresses the hydrogen-induced amorphization of the LaNi3.8 alloy. Moreover, during the charge–discharge cycling of the Mg-containing alloy electrode, the dissolutions of La and Ni in the alkaline solution can be suppressed remarkably due to the sacrifice of Mg, which correspondingly results in preferable cycling stability and an anti-corrosion capability of the La0.8Mg0.2Ni3.8 alloy electrode.

Evaluation of Tool Performance of Recycle-Type Fe<sub>3</sub>Al Based Alloy for Pure Cu

Recycle-type Fe3Al (hereinafter designated as Re-Fe3Al) based alloys reinforced by the carbides of TiC or ZrC were processed by the high frequency induction melting method using a high-carbon Cr steel sludge, Al can scraps and the transition metals of Ti or Zr. The carbides were synthesized by in-situ reaction between the transition metal and carbon in the molten iron aluminum alloy. Vickers hardness values are 309HV0.5 for Re-Fe3Al/TiC alloy, and 473HV0.5 for Re-Fe3Al/ZrC alloy, which are higher than that of P-Fe3Al (preprared from pure-Fe and-Al). The cutting performance of the Re-Fe3Al baed alloys was compared with a High-Speed-Steel (HSS) by cutting tests for pure-Cu extruded bar (C1020) using a lathe under a dry condition. Tool life limit was estimated from frank wear length after the cutting tests of C1020 by finish-machining. Tool life limit of Re-Fe3Al/TiC alloy is more than16 min; P-Fe3Al was 12 min; HSS was 8 min, Re-Fe3Al/ZrC alloy was 7 min at the cutting speed of 100m/min. Also, tool life limit of the Re-Fe3Al/TiC alloy was more than twice times as long as that of the HSS at the cutting speed of 300/min. The relationship between cutting speed and tool life limit clearly indicated that the Re-Fe3Al/TiC alloy was better than the HSS at a higher cutting speed. Therefore, it was concluded that Re-Fe3Al/TiC alloy has excellent cutting tool performance.

Influence of Sn substitution on the thermoelectric properties in YbAl3

The compound YbAl3 exhibits a very high power factor, but also rather a large thermal conductivity, leading to a low figure of merit. The solid solutions YbAl3−xSnx with x=0, 0.05, 0.10, 0.20, 0.30 and 0.50 were synthesized by high frequency induction melting, spark plasma sintering (SPS) and annealing treatment. The influence of Sn substitution on the thermoelectric properties of YbAl3 was investigated. The carrier concentration increases but the carrier mobility decreases with increasing x. The electrical resistivity of the sample does not increase apparently with increasing Sn content x until 0.10 but increases evidently with further increasing Sn content x. The absolute Seebeck coefficient increases with increasing Sn content x until 0.20 while the thermal conductivity decreases significantly with increasing x. As a result, the figure of merit ZT can be enhanced by the substitution of Sn for Al. The maximum ZT of 0.27 could be obtained in the YbAl2.90Sn0.10 at 300K, which is larger than 0.18 for the pure YbAl3 or 0.19 for the Sc-doped YbAl3.

Effects of Second Phase Yb5Sb3 on the Thermoelectric Properties of YbAl3

The compound YbAl3 exhibits a very high power factor but also rather a large thermal conductivity, leading to a low figure of merit. The second phase Yb5Sb3 was introduced in the YbAl3 matrix to reduce its thermal conductivity. The composites (YbAl3)1−x(Yb5Sb3)x with x = 0, 0.01, 0.05, 0.10, and 0.20 were synthesized by high frequency induction melting, annealing treatment, and spark plasma sintering. The thermoelectric properties of the composites were evaluated. The composites are of n-type conduction. The pure YbAl3 obtained in this work shows a high power factor of 11,500 μW m−1 K−2 but also a high thermal conductivity of 19.6 W m−1 K−1. However, the existence of Yb5Sb3 compound in the YbAl3 matrix enhances the electrical resistivity and the absolute Seebeck coefficient of the composite, but significantly reduces its thermal conductivity in the temperature range considered, thereby enhancing the figure of merit. The highest ZT value of 0.23 may be obtained in the sample (YbAl3)0.95(Yb5Sb3)0.05 at room temperature, which is apparently higher than that of pure YbAl3.

Influence of Rare Earth Elements on Microstructure and Mechanical Properties of Mg97Zn1Y1RE1 Alloys

Mg97Zn1Y1RE1 (RE=La, Ce, Nd and Sm, at. %) alloys were prepared by high-frequency induction melting in an Ar atmosphere. Rods were extruded at 623K and a ram speed of 2.5mm·s−1 using a circular die with an extrusion ratio of 10. The microstructure and mechanical properties of the extruded alloys were investigated. The Mg97Zn1Y1Nd1 and Mg97Zn1Y1Sm1 alloys consisted of only two phases: α-Mg and a Mg-RE intermetallic compound. The Mg97Zn1Y1La1 and Mg97Zn1Y1Ce1 alloys consisted of three phases: α-Mg, a Mg-RE intermetallic compound, and a Mg12ZnY phase with a long-period stacking ordered (LPSO) phase. Additionally, after extrusion, the three-phase Mg97Zn1Y1RE1 alloys, i.e., those with an LPSO phase, had a stratified microstructure and exhibited better mechanical properties than those without an LPSO. At room temperature, the yield strength and ultimate tensile strength of the three-phase Mg97Zn1Y1La1 and Mg97Zn1Y1Ce1 alloys were 381–384MPa and 427–429MPa, respectively, and yield strengths greater than 280MPa were observed at the elevated temperature of 523K.