Melting Point Of Metal Research Articles

Crack suppression in directed energy deposition of molybdenum

Additive manufacturing (AM) is a valuable tool for the fabrication and repair of refractory parts such as molybdenum alloys. Cracking is a common defect encountered during AM processing of refractory parts, that is generally associated with the segregation of light elements to grain boundaries which affect grain boundary cohesion and, ultimately, affect the final performance of the part. Similarly, because of the high melting points of refractory metals, lack-of-fusion defects are also common. The effect of build substrate and small alloying additions on suppression of defects during multilayer builds was investigated using directed energy deposition (DED) printing. Identical sample matrices were printed on three different build substrates: molybdenum (Mo), commercially pure titanium (Cp-Ti), and 316 stainless steel (316). Twenty-six usable samples were produced. Samples were cross sectioned, polished, and were characterized for total cross-section defect area. Additionally, samples from each substrate material were analyzed for grain boundary oxygen content. The strongest defect suppression, producing crack free material, was observed in samples printed on a Cp-Ti build substrate with a ten atomic percent addition of titanium in the molybdenum powder feed. The part quality was enhanced due to three factors: 1) the moderation of thermal diffusivity through a change in build plate material, 2) the suppression of light element segregation via increased solubility through titanium addition, and 3) a lack of brittle phase formation due to metallurgical compatibility of the build material with the build substrate. Analysis of defect area versus dimensionless number, π1, shows that increasing π1 reduced defects throughout the part.

Thermally stimulated structural evolution of bimetallic nanoplatelets - Changing from core-shell to alloyed to Janus nanoplatelets

Gold-based bimetallic nanostructures exhibit unique optical and catalytic properties that are strongly dependent on their composition and nanoscale geometry. Here we show the nano-structural transformation of mesoporous-silica-coated Au-M (Ag, Pd, Pt) core-shell nanoplatelets (NPLs) with a triangular shape to alloyed platelets at temperatures at least 300 °C below the lowest melting point of the metals while still retaining the out-of-equilibrium triangular shape and intact mesoporous shell. Before the alloying started the rough core-shell morphology of the Au–Pd and Au–Pt NPL systems were first observed to relax into a much smoother core-shell morphology. The alloying temperature was found to be related to the melting points and atom fractions of the shell metals; the higher the melting point and atomic fraction of the shell metal, the higher the temperature required for alloying. The highest alloying temperature was found for the Au–Pt system (650 °C), which is still hundreds of degrees below the bulk melting points. Surprisingly, a phase separation of Au and Pt, and of Au and Pd, was observed at 1100 °C while both systems still had an anisotropic plate-like shape, which resulted in Janus-like morphologies where the pure Pt and pure Pd ended up on the tips of the NPLs as revealed via in-situ heating in the scanning transmission electron microscope (STEM). The Janus-type morphologies obtained at elevated temperatures for the NPLs composed of combinations of Au–Pt and Au–Pd, and the smooth core-shell morphologies before alloying, are very interesting for investigating how differences in the bi-metallic morphology affect plasmonic, catalytic and other properties.

Ag Surface Outflow Kinetics in Ag/AlN Nanomultilayers

The heat‐induced microstructure evolution of nanomultilayers (NMLs) with metallic components is widely studied due to its critical importance in ensuring the reliable application of these nanomaterials. The thermal degradation of NMLs is controlled by mass transport of one of the NML components from the NML volume to its surface. The outflow occurs at temperatures well below the melting point of metal, offering new opportunities for the engineering of innovative NML‐based brazing fillers. A combined experimental‐modeling approach for the quantitative analysis of silver (Ag) outflow kinetics in Ag/AlN NMLs is presented. The method is based on in situ monitoring of the X‐ray diffraction intensity evolution of Ag acquired from the near‐surface region of NML (grazing incidence geometry) upon annealing in the temperature range of 230–425 °C (atmosphere of N2). The experimental data are compared to model predictions of Ag diffusion. It is assumed that Ag diffusion is driven by the relaxation of residual stresses in Ag nanolayers. Due to the multilayer geometry, the surface outflow kinetics are mainly defined by the kinetics of Ag diffusion along Ag/AlN interphase boundaries. The parameters defining the Ag surface outflow kinetics, i.e., diffusion coefficients and activation energy for diffusion, are derived.

Electron and ion emission characteristics of metal irradiated by nanosecond laser

Clarifying the electron and ion emission characteristics of metals irradiated by nanosecond focused laser in low pressure environment is crucial for improving applications based on laser-produced plasmas. This paper investigates the emission characteristics through electrical and optical diagnosis. The emission process is investigated through joint analysis of electrons and ions behavior, and relevant influencing factors are studied. The emission process of electrons and ions is divided into four stages, characterized by the arrival of prompt electrons e1, ultrafast electrons e2/ions i1, fast ions i2 and thermal electrons e3/ions i3, respectively. e1 is mainly related to thermal emission and photoemission, which can be improved by high electric field, gas pressure (within a certain range), laser energy and melting boiling points of target. e2/e3 and i1/i2/i3 mainly originate from laser ablation, and their expansion process follows obvious bipolar diffusion characteristics, while the latter is related to the different mass and charge states of the ions. The amplitude of i2 and e3 can be improved by using low density and melting point metals, and they are easily blocked by background gas, almost independent of the weak electric field.

In situ Investigations of the Formation Mechanism of Metastable γ-BiPd Nanoparticles in Polyol Reductions.

Synthesizing intermetallic phases containing noble metals often poses a challenge as the melting points of noble metals often exceed the boiling point of bismuth (1560 °C). Reactions in the solid state generally circumvent this issue but are extremely time consuming. A convenient method to overcome these obstacles is the co-reduction of metal salts in polyols, which can be performed within hours at moderate temperatures and even allows access to metastable phases. However, little attention has been paid to the formation mechanisms of intermetallic particles in polyol reductions. Identifying crucial reaction parameters and finding patterns are key factors to enable targeted syntheses and product design. Here, we chose metastable γ-BiPd as an example to investigate the formation mechanism from mixtures of metal salts in ethylene glycol and to determine critical factors for phase formation. The reaction was also monitored by in situ X-ray diffraction using synchrotron radiation. Products, intermediates and solutions were characterized by (in situ) X-ray diffraction, electron microscopy, and UV-Vis spectroscopy. In the first step of the reaction, elemental palladium precipitates. Increasing temperature induces the reduction of bismuth cations and the subsequent rapid incorporation of bismuth into the palladium cores, yielding the γ-BiPd phase.

Vacuum free self-fusion solidification bonding of aluminum by 60/40 brass insert metal

The self-fusion solidification bonding process occurs the isothermal fusion and the isothermal solidification by the reaction diffusion between the base metal and the dissimilar insert metal. The bonding process is carried out below the melting points of the base metal. 60/40 brass was used as the insert metal for the self fusion solidification bonding of aluminum in this study. The periodic motion under the load control was applied to the bonding interface at the bonding temperature. The joint by 60/40 brass insert metal was obtained at the bonding temperature of 893 K. The phases by the isothermal fusion and solidification in the bond were evaluated by the chemical composition of the phase and the ternary phase equilibrium diagram.

Current Status and Outlook of Low‐Melting‐Point Metals in Biomedical Applications

AbstractIn recent years, low‐melting‐point metals including liquid metals, exhibiting outstanding physical and chemical properties such as excellent thermal and electrical conductivity, high surface tension, and biocompatibility, have garnered increasing attention from researchers. The melting point of such metals profoundly influences their properties and determines their range of applications, and comprehending the characteristics and properties of low‐melting‐point metals is crucial for their future applications. Although studies related to liquid metals are growing exponentially in particular, reports exploring the properties and applications of low‐melting‐point metals from the perspective of the melting point are still in their early stages. This review aims to comprehensively summarize the key properties and relevant applications of current low‐melting‐point metals described in recent studies, focusing on gallium‐ and bismuth‐based metal alloys. In addition, this review discusses the opportunities and challenges associated with low‐melting‐point metals, and it is anticipated that this review will contribute to the advancement of low‐melting‐point materials in the fields of flexible electronics and biomedicine, particularly for biomedical applications.

Interfacial friction enabling ≤ 20 μm thin free-standing lithium strips for lithium metal batteries

A practical high-specific-energy Li metal battery requires thin (≤20 μm) and free-standing Li metal anodes, but the low melting point and strong diffusion creep of lithium metal impede their scalable processing towards thin-thickness and free-standing architecture. In this paper, thin (5 to 50 μm) and free-standing lithium strips were achieved by mechanical rolling, which is determined by the in situ tribochemical reaction between lithium and zinc dialkyldithiophosphate (ZDDP). A friction-induced organic/inorganic hybrid interface (~450 nm) was formed on Li with an ultra-high hardness (0.84 GPa) and Young’s modulus (25.90 GPa), which not only enables the scalable process mechanics of thin lithium strips but also facilitates dendrite-free lithium metal anodes by inhibiting dendrite growth. The rolled lithium anode exhibits a prolonged cycle lifespan and high-rate cycle stability (in excess of more than 1700 cycles even at 18.0 mA cm−2 and 1.5 mA cm−2 at 25 °C). Meanwhile, the LiFePO4 (with single-sided load 10 mg/cm2) ||Li@ZDDP full cell can last over 350 cycles with a high-capacity retention of 82% after the formation cycles at 5 C (1 C = 170 mA/g) and 25 °C. This work provides a scalable approach concerning tribology design for producing practical thin free-standing lithium metal anodes.

Effects of axial magnetic field on Fe-Ni interface macrosegregation of 9%Ni steel welds filled with Ni-based alloy

For the 9%Ni steel joint filled with nickel-based alloy, macrosegregation and wide partial mixing zone (PMZ) at Fe-Ni interface are critical factors to determine the cryogenic toughness. The pulsed gas metal arc welding (GMAW) assisted by the alternating axial magnetic field (AMF) is proposed to improve interface morphology and composition gradient. The welding without AMF assistance and with different AMF intensity are compared. The Lorentz force on arc and droplet caused by the alternating AMF is conductive to the stable transfer of viscous nickel-based alloy. The results show that AMF is effective to suppress the macrosegregation of Fe-Ni interface resulted from the temperature difference of melting point between base metal and filler metal. The temperature and flow speed of molten pool edge is enhanced by the stirring effect of AMF. The amount of filler metal in the PMZ of base metal increases. The melting point of mixing metal in PMZ decreases. Under the action of AMF, more PMZ is stripped from base metal. The PMZ continues to mix with liquid metal after entering the molten pool, instead of solidifying inside molten pool. After the alternating 12 mT AMF was applied, the cryogenic impact absorbed energy of fusion line increased from 0.85 J/mm2 to 1.29 J/mm2.

Twofold increase in the sensitivity of Er3+/Yb3+ Boltzmann thermometer

Luminescence thermometry is the most versatile remote temperature sensing technique and can be employed from living cells to large surfaces and from cryogenic temperatures to the melting points of metals. Ongoing research aims to optimize the sensitivity of the ratio between the emission intensity from two coupled excited states. However, this approach is inherently limited to temperature-dependent processes involving only the excited states. Here, we develop a novel measurement technique, called luminescence intensity ratio squared (LIR2) for the Yb3+/Er3+ pair, that combines the temperature sensitivity of ground- and excited-state populations. We use Y3Al5O12:Er3+,Yb3+ nanoparticles as a promising model system with both visible and infrared emissions. To apply our method, we record two luminescence spectra at different excitation wavelengths and determine the LIR2 using one emission in each of the two spectra. The LIR2 testing with Y3Al5O12 nanoparticles showed a sensitivity increase of 70% in the visible region and an impressive 230% increase in the NIR region compared to the conventional LIR method. This enhances the measurement precision by a factor of 1.5–2.5. The LIR2 based on the visible upconversion emission is particularly useful for measurements of high temperatures, while the LIR2 based on the downshifted ∼1.5 μm emission may revolutionize temperature measurements of biological samples in the range of physiological temperatures.

Metallurgical characterization and high-temperature tensile failure of Inconel 617 alloy welded by GTAW and SMAW—a comparative study

Two types of the weld joint of Inconel 617 alloy were produced using gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) processes with ERNiCrCoMo-1 filler metal and ENiCrCoMo-1 electrode, respectively. The weld metal showed the segregation of the principle alloying elements like Mo and Cr along the inter-dendritic spaces, triggering the formation of secondary phases. The microstructure characterization of the interface ensured the high dilution, which could be attributed to the closeness in melting point and chemistry of base and filler metal. Microhardness variation, tensile testing at room and high temperature, and Charpy impact test were conducted to investigate the effect of the Mo segregation in the weld zone and heterogeneity in the microstructure of weldments on the mechanical behavior of both the welded joints. The cross-weld tensile tests were conducted at room temperature and 550°C. The tensile test samples failed from the weld zone for each condition with a tensile strength value close to the base metal, which ensured the applicability of the joint for end service. The tensile strength of GTAW-RT, GTAW-HT, SMAW-RT, and SMAW-HT were measured as 766 ± 22 MPa, 570 ± 5 MPa, 760 ± 7 MPa, and 600 ± 8 MPa, respectively. A non-uniform hardness plot was witnessed with the hardness of the GTAW-weld and SMAW-weld zone of 257 ± 8 HV and 285 ± 5 HV, respectively, in the transverse direction. The impact toughness of the weld zone was 84 ± 2 J and 48 ± 4 J for GTAW and SMAW weld zone. The average impact toughness of the GTAW-weld zone was approximately 42% higher than the value of the SMAW-weld zone. In a nutshell, it can be concluded that the welded joint of Inconel 617 produced using the GTAW process with ERNiCrCoMo-1 filler had the best metallurgical and mechanical properties.

Understanding and Engineering Interfacial Adhesion in Solid-State Batteries with Metallic Anodes.

High performance alkali metal anode solid-state batteries require solid/solid interfaces with fast ion transfer that are morphologically and chemically stable upon electrochemical cycling. Void formation at the alkali metal/solid-state electrolyte interface during alkali metal stripping is responsible for constriction resistances and hotspots that can facilitate dendrite propagation and failure. Both externally applied pressures (35-400 MPa) and temperatures above the melting point of the alkali metal have been shown to improve the interfacial contact with the solid electrolyte, preventing the formation of voids. However, the extreme pressure and temperature conditions required can be difficult to meet for commercial solid-state battery applications. In this review, we highlight the importance of interfacial adhesion or 'wetting' at alkali metal/solid electrolyte interfaces for achieving solid-state batteries that can withstand high current densities without cell failure. The intrinsically poor adhesion at metal/ceramic interfaces poses fundamental limitations on many inorganics solid-state electrolyte systems in the absence of applied pressure. Suppression of alkali metal voids can only be achieved for systems with high interfacial adhesion (i. e. 'perfect wetting') where the contact angle between the alkali metal and the solid-state electrolyte surface goes to θ=0°. We identify key strategies to improve interfacial adhesion and suppress void formation including the adoption of interlayers, alloy anodes and 3D scaffolds. Computational modeling techniques have been invaluable for understanding the structure, stability and adhesion of solid-state battery interfaces and we provide an overview of key techniques. Although focused on alkali metal solid-state batteries, the fundamental understanding of interfacial adhesion discussed in this review has broader applications across the field of chemistry and material science from corrosion to biomaterials development.

Neutrosophic Lindley distribution with application for Alloying Metal Melting Point

In the field of survival analysis, the Lindley distribution is used to mimic methods used with human lifespan data. A variety of survival statistics with indeterminacies are intended to be characterized by the neutrosophic Lindley distribution (NLD). In example, modeling unknown data that is roughly positively skewed makes use of the established distribution. The neutrosophic survival function, neutrosophic hazard rate, and neutrosophic moments are three of the developed NLD's major statistical features that are discussed in this article. Additionally, the well-known maximum likelihood estimation method is used to estimate the neutrosophic parameters. A simulation study is conducted to see whether the projected neutrosophic parameters were attained. Not to mention that discussions of prospective NLD real-world applications have made use of actual data. To demonstrate how well the suggested model performed in comparison to the existing distributions, actual data were used.

Bismuth-mesoporous silica-based phase change materials for thermal energy storage

Effective heat storage at temperatures above 200 °C enables large scale, concentrated solar thermal energy storage or heating applications. Metals can be used for latent heat storage, as they provide high volumetric energy densities at low cost. The volume change during transition limits their stability, but it can be overcome through encapsulation or impregnation into porous matrices. We report the first study on Bismuth-based phase change materials using mesoporous silica matrices or silica shells. High metal fractions (50–70% wt.) were obtained. The metal phase form sub-micron sized domains, with good dispersion inside the silica matrix. Samples obtained by encapsulation show low enthalpy and reliability. High enthalpy values (22–32 Jg−1), comparable to that of Bi particles were obtained for samples containing mesoporous silica. These composites exhibit good thermal reliability and shape-stability above the metal melting point, in contrast to Bi particles, which show molten metal leakage. Nanoconfinement of the metal phase decreases its melting point by 1–3 °C and its heat of fusion by less than 1%. The good heat storage capacity of composites containing 70% wt. Bi could be explained by a reduction in metal oxidation, caused by the presence of the mesoporous silica matrix.

Microstructure and properties of MgAlCd filler metal scraped brazing AZ31 magnesium alloy joint

In order to simplify the brazing process of magnesium alloy and make the liquid filler metal rapidly wet the base metal, the phase diagram method was used to design the series of Cd22.8Mg9.2Al and Cd26.3Mg15.3Al series filler metal. The brazing of AZ31 magnesium alloy was realized by scraping brazing under the condition of flame heating. The microstructure and phase of the filler metal and brazing seam were analyzed by XRD, SEM, and EDS. The results show that the microstructure of filler metal is composed of CdMg matrix, granular Al12Mg17, and massive (Al) solid solution. The amount of Al12Mg17 and (Al) solid solutions in filler metal increases with the increase of Al content, and the hardness of filler metal also increases. The Al content increases from 9.2 to 15.3%, and Vickers hardness increases from 183.6HV to 252HV. DSC results show that the melting point of filler metal is between 396.1 °C and 401.5 °C. The analysis results of the brazing seam show that the microstructure of the brazing seam is composed of CdMg3 and Al12Mg17. With the increase of Al content in filler metal, the fracture morphology changes from a river like pattern to rock sugar shape, the fracture mode changes from trans-granular fracture to intergranular fracture and the shear strength of joint decreases from 71 MPa to 53 MPa. The main reason for this phenomenon is the increase in the amount and size of the Al12Mg17 phase.

CMT arc-assisted thermo-compensated resistance brazing welding immiscible pure copper to 304 stainless steel

• The optimized Cu/steel interface was achieved by CMT pre-surfacing. • High-strength joints fractured in the Cu base metal were obtained. • The resistance brazing feature was manifested by molten amorphous alloy foil. The high-strength Cu alloy/stainless steel joints were obtained by a novelty hybrid welding technology (CMT arc-assisted thermo-compensated resistance brazing welding). Experimental results indicated that the traditional Cu/steel connection was converted into the Cu/Cu connection in the final welding process successfully utilizing the Cu insert layer by pre-surfacing. The maximum temperature of the welded joints in the whole process was less than the melting point of the base metal but greater than the melting point of the interlayer, achieving the brazing feature. Cu solid solutions (s.s), Fe 2 Si intermetallic compound (IMC), and a mechanical interlock were comprised at the interface, resulting in all the tensile-shear specimens fractured at the Cu base metal.

Rigid Procedure to Calculate the Melting Point of Metal Using the Solid-Liquid Phase (Coexistence) Method

Melting point, particularly metal, is one of the important data for many applications. For developing new materials, adequate theories for melting point are very crucial. The determination of melting point using the popular phase-change curve method is very easy but usually overestimate. In current work, we determine the melting point of a pure metal (iron) using the method of solid-liquid phase coexistence. For this goal, molecular dynamics simulation was applied to obtain data of trajectories of atoms. Simulation (LAMMPS) and data analysis (OVITO) procedures are strictly applied to obtain the accurate melting point of iron based on the obtained trajectories data. For initial structure design of simulation, we used the ATOMSK program. The melting point of iron obtained using the phase change curve (PCC) method is about 2750 K < TPCC < 3250 K and using the coexistence phase (CP) method is TCP = 2325 K. A more accurate calculation needs to include defects factor in the simulated material and calculation. In this research we use the Morse potential to represent all of the atomic interaction among atoms of Fe material.

A Review of the Brazeability of Low-Temperature and Nano-Reinforced Al-Based Brazing Filler Metals

Aluminum and its alloys are some of the most widely used materials for the brazing of parts in aerospace and automotive industries due to their excellent physical characteristics, e.g., good ductility, high strength-to-weight ratio, light weight, good corrosion and oxidation resistance, satisfactory malleability and formability, and excellent thermal and electrical conductivity. Especially during casting operations, high strength and machinability of Al-based alloys are of utmost concern. The quality and strength of casting products are affected by porosity generated due to the dissolution of gases and the effects of modifiers. Thus, unstable properties of Al alloys arising due to such influences should to be controlled by reinforcing suitable elements. Compared to other materials, brazing on Al requires higher control precision as the difference between the melting points of the base metal and the filler remain low even after the addition of melting point suppressants, such as Si. This necessitates the development of novel low-temperature Al-based filler metals. Moreover, the mechanical properties of Al-based alloys can be enhanced by introducing nanoparticles within them to reduce the thickness of Si-needles and IMCs (intermetallic compound) within the Al matrix, thereby refining the nanostructure.

Full-color generation enabled by refractory plasmonic crystals

Abstract Plasmonic structural color, in which vivid colors are generated via resonant nanostructures made of common plasmonic materials, such as noble metals have fueled worldwide interest in backlight-free displays. However, plasmonic colors that were withstanding ultrahigh temperatures without damage remain an unmet challenge due to the low melting point of noble metals. Here, we report the refractory hafnium nitride (HfN) plasmonic crystals that can generate full-visible color with a high image resolution of ∼63,500 dpi while withstanding a high temperature (900 °C). Plasmonic colors that reflect visible light could be attributed to the unique features in plasmonic HfN, a high bulk plasmon frequency of 3.1 eV, whichcould support localized surface plasmon resonance (LSPR) in the visible range. By tuning the wavelength of the LSPR, the reflective optical response can be controlled to generate the colors from blue to red across a wide gamut. The novel refractory plasmonic colors pave the way for emerging applications ranging from reflective displays to solar energy harvesting systems.

Study of Impingement Cooling Technology by Using Circular Pin Fins and Mist/Air Methods in Gas Turbine Combustor

The gas turbine is an indispensable part of technology and it is commonly used in electric power, aviation and marine mechanical. However, the gas combustion temperature was higher than the melting point of metal, which prevents further increase in efficiency in a gas turbine. To enhance the turbine inlet temperature greatly, an advanced cooling technology has been essentially required to protect the material of high thermal components. The final numerical results are compare with each other and show the characteristics of heat transfer and pressure drop. In these investigations, different cases evaluate that the adiabatic cooling effectiveness (ηc ) indicates a downward curvature in the following descending order: circular pin fin with mist case = circular pin fin only case > normal with mist cooling case > normal with air only case. Mist/air impiangement cooling with circular pin fins not only maintain the superiorities of air cooling jets, but more effective than pin fins technique. Accordingly, renewing the air impingement cooling systems with pin fins and mist cooling seems to be more attractive. The inspire application of the circular pin fins and mist/air impingement cooling will make it a reference for designing a new cooling structure in marine gas turbine combustor.