Low Melting Point Metal Research Articles

Low-Temperature Multielement Fusible Alloy-Based Molten Sodium Batteries for Grid-Scale Energy Storage.

The sustainable future of modern society relies on the development of advanced energy systems. Alkali metals, such as Li, Na, and K, are promising to construct high-energy-density batteries to complement the fast-growing implementation of renewable sources. The stripping/deposition of alkali metals is compromised by serious dendrite growth, which can be intrinsically eliminated by using molten alkali metal anodes. Up to now, most of the conventional molten alkali metal-based batteries need to be operated at high temperatures. To decrease the operating temperature, we extended the battery chemistry to multielement alloys, which provide more flexibility for wide selection and rational screening of cost-effective and fusible metallic electrodes. On the basis of an integrated experimental and theoretical study, the depressed melting point and enhanced interfacial compatibility are elucidated. The proof-of-concept molten sodium battery enabled by the Bi–Pb–Sn fusible alloy not only circumvents the use of costly Ga and In elements but also delivers attractive performance at 100 °C, holding great promise for grid-scale energy storage.

Crystallization temperatures of complex ferroalloys

Thermo-gravimetric method was used to determine the temperature of crystallization onset of alloys of the Fe – Ni – Cr – C – Si system depending on concentration of chromium and nickel. It was shown that complex ferroalloys containing 0.2 – 21.0 % Ni (at Cr = 25 – 28 %); 0.5 – 45.0 % Cr (at Ni = 10 – 11 %); 2.0 % C and 0.3 % Si, iron, and impurities belong to the category of low-melting alloys and have rational values (1320 – 1400 °C) of crystallization temperatures in terms of their use for steel processing in the ladle. An increase of the chromium content to more than 45 % in these alloys is accompanied by an intense increase of their temperatures of the crystallization onset.

Self-organized Bi-rich grain boundary precipitates for realizing steep magnetic-field-driven metamagnetic transition in Bi-doped Mn2Sb

In the present work, we reveal a novel finding, that is, self-assembled grain boundary precipitates for realizing the magnetic-field-induced metamagnetic transition by employing low melting point metal in materials. This strategy has been experimentally verified in a well-established ferrimagnetic compound Mn2Sb by doping the bismuth (Bi) element with a low melting point of just 271.3°C. Bi solidifies later than the Mn2(Sb,Bi) main phase in (Mn2Sb)1-xBix system (the melting point of ~948°C for Mn2Sb), and aggregates spontaneously along the grain boundaries, forming Bi-rich grain boundary precipitates to coat main phase grains. This is very similar to the Nd-rich grain boundary phase in Nd-Fe-B permanent magnets. The fraction of Bi-rich grain boundary phase can be controlled by Bi-content. As a result, the magnetic field induced steep magnetoelastic transition from antiferromagnetic to ferrimagnetic is achieved in (Mn2Sb)0.89Bi0.11 alloy with giant multiple functional properties in Bi-doped Mn2Sb. Especially, the magnetic entropy change maximum nearly quadruples when Bi-doping increases from 0.03 to 0.11. Giant negative magnetoresistance of more than 65% under μ0∆H = 0–5 T, and magnetostrain of ~1802 ppm under μ0H = 8.5 T are obtained in (Mn2Sb)0.89Bi0.11. It should pave a way to achieve the magnetic transition and enhance the magnetoresponsive effects in designing similar coherent materials by employing low melting point metal doping to form the dual-phase heterogeneous structure.

Sn addition effects on CaKFe4As4 superconductors

The effects of adding low-melting point metals (Pb, Sn, In and Ge) to polycrystalline CaKFe4As4 (CaK1144) superconductors were investigated. We found that Sn is the most stable with CaK1144 among these low-melting point metals. Synthesis conditions as well as the doping quantity of Sn were optimized, and phase stability, microstructures and superconducting properties were investigated. At the optimized sintering temperature of 700 °C, Sn was effectively solidified in grain boundaries (GBs) of the CaK1144 bulk samples and secondary phase formations were not serious in optimized samples. As the Sn amount increased, filling of Sn in the GBs increased up to 30 wt% with homogeneous dispersion. The magnetic field dependence of critical-current density (Jc) was significantly enhanced by 30 wt% Sn addition and decreased with further increase of Sn addition. The filling up of 1144 grain boundaries by the optimal amount of Sn enhanced the Jc from 11.7 kA cm−2 to 21.7 kA cm−2 in a self-field and at 4.2 K. Sn addition was effective both to suppress the impurity phases as well as increase Jc of CaK1144.

Mechanical properties of electrochemically lithiated Sn

Sn is a promising Li ion battery anode with high theoretical capacity, but it can easily pulverize due to repeated application of extreme volumetric strain of 260% during cycling. Sn is a low melting point metal with low modulus and therefore has previously been proposed to be a fracture resistant anode due to its the ability to relax stresses via plasticity and creep deformations. In this study, intrinsic mechanical properties of lithiated Sn at various stages in the lithiation were evaluated using nanoindentation experiments using a special setup. In order to avoid oxidation of the highly reactive lithiated Sn, nanoindentation was performed on specimens submerged in a mineral oil bath. After careful calibration, hardness and modulus of different phases of lithiated Sn were evaluated. With an increase in the lithium content, both the modulus and hardness of the lithiated Sn decreased, as expected, where the modulus and hardness are 28.6 GPa and 0.37 GPa, respectively, for fully lithiated Sn (Li22Sn5) and 58.0 GPa and 0.77 GPa, respectively, for unlithiated Sn. This is the first report on the mechanical properties of lithiated Sn, which is expected to be of importance in theoretical analysis of the diffusion induced stresses in Sn anodes.

Measurement uncertainty analysis of field-programmable gate-array-based, real-time signal processing for ultrasound flow imaging

Abstract. Research in magnetohydrodynamics (MHD) aims to understand the complex interactions of electrically conductive fluids and magnetic fields. A promising approach for investigating complex instationary flow phenomena are lab-scale experiments with low-melting alloys. They require a noninvasive flow instrumentation for opaque liquids with a high spatiotemporal resolution, a low velocity uncertainty and a long measurement duration. Ultrasound Doppler velocimetry can achieve multiplane, multicomponential flow imaging with multiple linear ultrasound arrays. However the average raw data output amounts to 1.2 GBs−1 at a frame rate of 33 Hz in a typical configuration for 200 transducers. This usually prevents long-duration measurements when offline signal processing is used. In this paper, we propose an online signal-processing chain for pulsed-wave Doppler velocimetry that is tailored to the specific requirements of flow imaging for lab-scale experiments. The trade-off between measurement uncertainty and computational complexity is evaluated for different algorithmic variants in relation to the Cramér–Rao bound. By utilizing selected approximations and parameter choices, a prepossessing could be efficiently implemented on a field-programmable gate array (FPGA), enabling a typical reduction of the data bandwidth of 6.5:1 and online flow visualization. We validated the performance of the signal processing on a test rig, yielding a velocity standard deviation that is a factor of 3 above the theoretical limit despite a low computational complexity. Potential applications for this signal processing include multihour flow measurements during a crystal-growth process and closed-loop velocity feedback for model experiments.

A low-temperature bonding method for high power device packaging based on In-infiltrated nanoporous Cu

With the rapid development of the third-generation semiconductor materials, an appropriate high-temperature-resistant die attach material has become one of the bottlenecks to fully exploit the excellent properties of the third-generation semiconductor power devices. At the same time, a low-bonding temperature is always the pursuit goal of packaging engineers to reduce the thermal residual stress in electronic devices. In this paper, a low-temperature bonding method was proposed to address the above-mentioned issue based on In infiltrating the nanoporous Cu. In, as a low melting point metal, can significantly reduce the bonding temperature, and the nanoporous Cu structure can provide a very large specific surface area, which greatly increases the consumption rate of In. Furthermore, the formed Cu-In IMCs with high-remelting temperature can withstand the high operating temperature. The microstructures of the bondlines before and after bonding were studied in detail. The results show that the bondline can completely consume the low melting point In, within 10 min at 165 °C under a pressure of 0.75 MPa. When the bonding temperature was further increased to 310 °C, the bondline was composed of η-Cu2In and δ-Cu7In3 phases, whose melting points were more than 600 °C. The average electrical resistivity was determined to be 5.53 ± 0.65 μΩ cm, and the thermal conductivities were 144.33 W m−1 K−1, 139.24 W m−1 K−1 and 129.79 W m−1 K−1 at 30 °C, 150 °C and 300 °C, respectively. The average shear strength were 19.09 ± 3.4 MPa, 20.47 ± 4.6 MPa and 30.73 ± 5.2 MPa at 30 °C, 250 °C, 310 °C, respectively. These results indicate that the nanoporous Cu infiltrated with In could meet the requirements of electrical, thermal conduction, and mechanical support as a die attachment for high-power devices.

Next-Generation Liquid Metal Batteries Based on the Chemistry of Fusible Alloys.

With a long cycle life, high rate capability, and facile cell fabrication, liquid metal batteries are regarded as a promising energy storage technology to achieve better utilization of intermittent renewable energy sources. Nevertheless, conventional liquid metal batteries need to be operated at relatively high temperatures (>240 °C) to maintain molten-state electrodes and high conductivity of electrolytes. Intermediate and room-temperature liquid metal batteries, circumventing complex thermal management as well as issues related to sealing and corrosion, are emerging as a novel energy system for widespread implementation. In this Outlook, we elaborate the appealing features of fusible alloys-based liquid metals for energy storage devices and describe the metallurgical fundamentals, cost, and safety analysis of fusible alloys. Recent advances are discussed covering the rational screening of metallic alloys, interfacial engineering on the electrodes, and design of advanced electrolytes. In the end, we provide perspectives on current challenges and future opportunities in this field. This outlook not only aims to provide a design principle for high performance liquid metal batteries, but also inspires further development of novel energy systems beyond conventional solid-state batteries and high-temperature batteries.

Physical and chemical properties of Fe-Ni-Cr-С system ferroalloys

Poor domestic oxidized nickel and chrome ores make it impossible to obtain of them standard ferroalloy grades using existing technologies. Obtaining new types of ferroalloys, including complex alloys of Fe-Ni-Cr- С system, is a perspective way to use the poor mineral raw materials. One of the factors restraining a mass production and consumption of new types of ferroalloys at steel-works, is absence of information about physical and chemical characteristics of the alloys. In view of this, basic physical and chemical properties of new chrome-nickel ferroalloys were studied. Experimental samples of complex nickel-based ferroalloys were smelted, containing 0.2-21% of Ni, 0.5-55 % of Cr, ~2 % of С and the balance - iron and impurities. Using thermogravimetric method, temperature of crystallization commencement was studied, using pycnometer, Fe-Ni-Cr- С system alloys density was measured depending on chrome and nickel concentration. It was shown that input of nickel in the alloys results in stable decreasing of their crystallization temperatures. The complex chrome-nickel ferroalloys, containing 0.2-21 % of Ni, 0.5-46 % of Cr are related to low-melting alloys and have rational values (1320-1400°C) of crystallization temperatures from the point of view of their application for steel ladle treatment. Further increase of chrome concentration results in non-desirable increase of the alloys crystallization temperatures and come to category of high-melting alloys. All the studied samples by density are referred to heavy alloys group. To reach optimal values of ferroalloys density (5000-7000 kg/m3) it is necessary to add to their composition elements with low values of density, for example, silicon.

Determination of Low-Melting Alloys in the Ternary Systems NaCl–NaI–Na2WO4 and KCl–KI–K2WO4

The ternary systems with a common cation, NaCl–NaI–Na2WO4 and KCl–KI–K2WO4, were studied by differential thermal analysis. The composition point of the congruently melting compound NaCl ⋅ Na2WO4 formed in the NaCl–Na2WO4 system divides the NaI–NaCl–Na2WO4 system into two triangles, in each of which there is a ternary eutectic. The characteristics of invariant points were determined, and phase equilibria in the studied systems were described.

Hydrodynamic Model of a Wedge-Shaped Sliding Support with an Easy-Melting Metal Coating

This study presents the method of forming an exact self-similar solution to the problem of hydrodynamic computation of a wedge-shaped support (slider, guide), which operates in the presence of a lubricant, a fusible metal coating on the surface of the guide, and a porous material on the surface of the slider taking the dependence of the viscosity of the lubricant and the permeability of porous material on pressure into account.

Room-Temperature All-Liquid-Metal Batteries Based on Fusible Alloys with Regulated Interfacial Chemistry and Wetting.

Liquid metal batteries are regarded as potential electrochemical systems for stationary energy storage. Currently, all reported liquid metal batteries need to be operated at temperatures above 240 °C to maintain the metallic electrodes in a molten state. Here, an unprecedented room-temperature liquid metal battery employing a sodium-potassium (Na-K) alloy anode and gallium (Ga)-based alloy cathodes is demonstrated. Compared with lead (Pb)- and mercury (Hg)-based liquid metal electrodes, the nontoxic Ga alloys maintain high environmental benignity. On the basis of improved wetting and stabilized interfacial chemistry, such liquid metal batteries deliver stable cycling performance and negligible self-discharge. Different from the conventional interphase between a typical solid electrode and a liquid electrolyte, the interphase between a liquid metal and a liquid electrolyte is directly visualized via advanced 3D chemical analysis. Insights into this new type of liquid electrode/electrolyte interphase reveal its important role in regulating charge carriers and stabilizing the redox chemistry. With facile cell fabrication, simplified battery structures, high safety, and low maintenance costs, room-temperature liquid metal batteries not only show great prospects for widespread applications, but also offer a pathway toward developing innovative energy-storage devices beyond conventional solid-state batteries or high-temperature batteries.

The effect of phase change material balls on the thermal characteristics in hot water tanks: CFD research

Hot water storage tank is the crucial element in solar energy utilization systems. Phase change material can significantly improve the thermal efficiency and the heat storage of hot water tank. In this study, a 3-D model for hot water tank with low melting point metals, sodium acetate trihydrate, and paraffin wax was established and validated by the experimental results. The influence of the inlet flow rates, the thermal conductivity and positions of the phase change materials on thermal characteristics of the hot water tank had been investigated. Results show that the hot water tank with low melting point metals has better performance due to its high thermal conductivity. Besides, with the inlet flow rate of 9 L/min, the released heat energy of the low melting point metals, the sodium acetate trihydrate and the paraffin wax water tanks are 17.22 MJ, 16.77 MJ and 16.37 MJ with the melting rates at the end time of 0%, 28% and 47%, respectively. In addition, as the inlet flow rate varies from 5 L/min to 9 L/min, the distances between the isothermal surfaces (35 °C and 75 °C) of the low melting point metals, the sodium acetate trihydrate and the paraffin wax water tanks increases from 3.98 cm to 7.96 cm, 5.49 cm to 8.57 cm and 5.82 cm to 8.87 cm, respectively, thus, the filling efficiency and Richardson number of the hot water tank with low melting point metals are the highest at the same inlet flow rate and position of the phase change material balls. Therefore, the application of low melting point metals as a phase change material in hot water tank not only can improve the heat storage capacity, but also increase thermal stratification.

HTS-WISE Conductor and Magnet Impregnated With Low-Melting Point Metal

A High-Temperature Superconducting (HTS) conductor and magnet impregnated with low-melting point metal named “WISE” (Wound and Impregnated Stacked Elastic tapes) has been invented. This paper reports results on the first trial of the WISE conductor/magnet and its testing. An HTS solenoid coil without turn-to-turn insulation in accordance with the WISE concept was fabricated and tested. The flexibility of HTS-WISE conductor allowed handmade coil winding. In the first charging test after impregnation, there was no degradation due to thermal contraction. However, it was observed that thermal cycle damaged the HTS tapes after the second cooling. Even with some degradation, the sample achieved a central magnetic field of 0.16 T, having an 800 A current in the steady-state. Despite the appearance of an electric field of ∼1 mV/m along the conductor, quench did not occur. In the overcurrent test, self-protection characteristics of a non-insulation coil appeared. These results show that WISE is a smart winding method for making robust HTS coils having even complex 3D shapes.

Abietic acid encapsulated Sn-57Bi alloy nanoparticles as oxidation resistant solder material

Low-melting point solder Sn-57Bi alloy nanoparticles were synthesized and encapsulated with abietic acid (aa) thin layer to form a core-shell structure. Formation of nanoparticle enhances its mechanical strength by decreasing strain value. Comparing to traditional rosin-alloy mixture (solder paste), the core-shell structure is more efficient on metal oxide reduction due to interaction enhancement and contacting area enlargement between alloy nanoparticles and abietic acid. Thin film can be formed through reflowing core-shell nanoparticles on copper foil. This research is beneficial on developing an efficiently oxidation resistant solder for electronic packing.

Plasma-molten Metal and/or Liquid Interactions for Materials/Chemical Processing

Several grand challenges in energy storage and conversion need the discovery of functional materials that many agree will be composed of complex compositions at nanoscale. In this regard, plasma based materials processing has been shown to be promising for combinatorial techniques and scalable processing. The use of plasma oxidation of liquid precursors allows for creation of metastable complex oxide particles with compositional control.1 A number of examples will be discussed in which the above two techniques are currently being used for accelerating the development of a variety of catalysts including electrocatalysts and materials for storage applications.This talk will highlight our efforts to understand the role of plasmas under two categories: (a) the synergistic effects hydrogen and nitrogen plasma interactions with molten metals;2 and (b) the oxygen plasma-liquid droplet interactions.3 To gain insights into these mechanisms we have studied the interaction of hydrogen and nitrogen plasmas with low melting point metals, primarily with gallium. Absorption/desorption experiments as well as theoretical-computational calculations were performed. Experiments have shown an increment of adsorbed gaseous species into the molten metal in the presence of plasmas. In the case of oxygen plasma-liquid droplet interactions for creating complex oxides, the role of solvated electrons, oxygen radicals and heating effects will be discussed. Finally, the use of plasmas for achieving liquid phase epitaxial growth of GaN and related materials will be discussed.4 Author acknowledge primary funding support from NSF Solar Project (DMS 1125909), and NSF EPSCoR (1355438).

Ultrasonic Preparation of Submicron Low Melting Point Alloy Powder

In order to study the preparation of low-melting alloy powder in phase change materials, three sets of control experiments were set up in this paper. To explore the effects of ultrasonic oscillation, ultrasonic atomization technology and rapid cooling had an effect on the particle size, surface morphology and powder shape of ultrasonic powder making. In the experiment, ultrasonic atomization, rapidly cooling ultrasonic atomization, and ultrasonic vibration generated powder were tested. The results showed that the surface of fog droplets generated by ultrasonic atomization was smooth, with distinct particles. The powder diameter was large, ranging from 20-60 μm. The surface of the powder obtained by ultrasonic shock existed an aggregation phenomenon. The powder diameter was small ranging from 5-10 μm. The ultrasonic atomized powder obtained by rapid cooling was mostly spherical with a smooth surface. After the screening, spherical powder with a diameter of 15-25 μm and the smooth surface could be obtained. The results showed that the particle diameter is small and uniform, while the uneven surface was difficult to eliminate. The experimental conditions of rapid cooling were favorable for the smoothness of the particle surface and the roundness of powder shape. Spherical powder with a diameter of 15-25 μm can be obtained by screening the rapidly cooled powder after ultrasonic atomization. Different experimental conditions and technological approach can produce high-performance low melting point alloy powder.

A cold forging process for producing thin-walled hollow balls from tube using a plastic insert

This paper investigates a cold forging process for producing hollow balls made of an aluminium alloy. The forging with an outside diameter of 30 mm is formed from a tube section with a 2-mm wall thickness. Preliminary tests have shown that in traditional die forging, the use of a billet with such a small relative thickness not only limits the range of applicable geometric parameters but also causes buckling. The authors propose to solve this problem by using an additional tool that has an active effect on the inner surface of the workpiece, and thus makes it possible to control the forging process conditions. The tool is a plastic insert, i.e., an additional flexible core made of a low-melting alloy. Theoretical and experimental results presented in this paper provide a considerable insight into the cold forging process for thin-walled hollow balls. The effects of the plastic insert geometry and dimensions on the forging process are also examined. A solution is proposed to ensure that the forged part meets all requirements.

Temperature and rate dependent constitutive behaviors of low melt Field ’s metal

Low melting point metals such as Field’s metal and gallium are increasingly used as transition phases in stiffness-tuning soft materials and devices. Nevertheless, there is a knowledge gap on the fundamental constitutive behaviors of metals with melting points below 100℃. This letter reports the stress–strain relationships of Field’s metal at various temperatures and strain rates. This metal has the lowest melting point among metals and alloys whose constitutive behaviors have been studied systematically. Experimental results indicate that Field’s metal exhibits a strain-softening behavior, in oppose to the strain-hardening behaviors of most engineering metals and alloys. A modified Johnson–Cook model is devised in this letter to describe the constitutive behaviors of Field’s metal. The proposed model will facilitate the design and analysis of functional materials and structures consisting of Field’s metal.

Characterization of surface modification by laser cladding using low melting point metal

A bearing is an essential mechanical element that is used to fix the axis of a rotating machine and helps rotate the shaft while supporting its weight and load. Numerous types of bearings have been developed depending on the functions and sizes of the machines in which they are utilized. In particular, power generating units such as gas turbines use medium or large hydraulic bearings for smooth operation. White metal is a tin alloy and a soft material that is often bonded to the inner surfaces of medium and large bearings to lubricate and protect the bearing shafts. Currently, gravity or centrifugal casting is used to bond the white metal to the surface of the bearing material. The casting process requires pretreatments such as chemical treatment and preheating and has many disadvantages with respect to the work environment, worker safety, productivity, and potential for automation. In this study, the process of binding white metal to bearings is simplified and improved by applying a laser cladding using powdered white metal. Depositing a metal that has a very low melting point compared to the base metal is different from the conventional cladding process; therefore, the focus of this work is to analyze the new cladding procedure for various process conditions. White metal specimens fabricated with this laser cladding were evaluated using cross-section images, hardness tests, and energy-dispersive X-ray spectroscopy analysis.