Presence Of Intermetallic Compounds Research Articles

Optimization of insert roughness and pouring conditions to maximize bond strength of (Cp)Al-SS304 bimetallic castings using RSM-GA coupled technique

The integration of ferrous and non-ferrous materials represents a breakthrough in materials technology, enabling the fabrication of functionally graded lightweight components with enhanced properties. In this study, a Box-Behnken design of experiments was employed to investigate the effects of pouring temperature, insert temperature, insert thickness, and surface roughness on the bond strength of bimetallic components. Shear punch tests were conducted to assess the maximum loads before fracture, with the highest bond strength of 17.04 MPa achieved under specific processing conditions. The presence of intermetallic compounds, including Fe2Al5, FeAl2, and Fe4Al13, contributed to the observed increase in reaction layer thickness. Response surface methodology revealed concentric responses for pouring temperature and surface roughness with an optimal predicted bond strength of 18.02 MPa. Further optimization using Genetic Algorithm resulted in a maximum bond strength of 19.20 MPa. These findings demonstrate the potential for producing high-performance bimetallic components tailored for applications in various industries.

Effect of reduction rate on microstructure and properties of laminated steel/aluminium low density composites prepared by hot pressing

ABSTRACT A multi-layer composite material consisting of 316 L steel and Al6061 aluminium was prepared via hot pressing. The mechanical properties of this heterogeneous layered composite material were studied under various reduction rates. The results revealed that the overall performance of the material initially improved and then declined as the reduction rates increased. Notably, at a hot pressing temperature of 400°C, the material exhibited optimal performance at a reduction rate of 32%. Furthermore, finite element simulations of the material processing process were performed using ABAQUS software, and the stress-strain state was analysed. The findings indicated that the overall performance of the material is influenced by both the presence of intermetallic compounds (IMCs) at the interface and the shear stress at the interface. In comparison to the aluminium layer, the performance of the steel layer undergoes more pronounced changes at the same reduction rate.

Study on interfacial morphologies of AA1060 and SS321 magnetic pulse welded joints

In this study, the application of magnetic pulse welding was employed for the production of tubular joints using 1060 aluminium and 321 stainless steel. Two crucial process parameters, the charging voltage, and the gap between the outer and inner tubes, were subjected to mechanical property tests and morphology analysis. The joints that exhibited favourable mechanical properties were obtained with a gap size of 1.25 mm and a charging voltage exceeding 3.5 kV. The presence of intermetallic compounds at the joint interface indicates the occurrence of fusion in the transition zone. The quantity of molten metal increased with an increase in the charging voltage. The aluminium content in the intermetallic compounds within the transition zone decreased as one moved from the 1060 aluminium side towards the 321 stainless steel side. The gap distance plays an important role in determining the efficiency of energy transformation at the joint interface during magnetic pulse welding (MPW). A smaller gap distance resulted in a substantial amount of energy being transformed into plastic deformation in the transition zone. Conversely, a greater gap distance led to a significant amount of energy from the electrical charging voltage being converted into thermal energy. The MPW joint consisted of bonding, mechanical interlock, and non-bonding regions. The mechanical properties of the joint were influenced by the composition of the intermetallic compound. Taking into account the impact of morphologies and elastic modulus of the transition zone, an increase in the melting of stainless steel during the welding process was found to be advantageous for the MPW of 1060 aluminium to 321 stainless steel.

Revealing hot tear formation dynamics in Al–Cu alloys with X-ray radiography

Hot tears can arise during the late part of alloy solidification because of the shrinkage of isolated liquid as it turns to solid and may have a catastrophic effect on cast tensile properties. Although there are correlations to suggest alloy hot tear sensitivity to casting conditions, they do not capture the influence of microstructure on tearing, such as second-phase particles or intermetallic compounds (IMCs) commonly present in engineering alloys. We use in situ X-ray radiography to quantify the formation and growth behaviour of hot tears in Al-5Cu and Al-5Cu-1Fe alloys during solidification. An automated hot tear detection, tracking and merging algorithm is developed and applied to reveal the role of Fe-rich IMC particles, typical of recycled alloys, on hot tear behaviour. These defects are termed hot tears here on the basis of their complex, extended inter-connected morphology, distinct from more rounded shrinkage porosity. We also visualise and quantify the velocity of interdendritic flow driven by solidification shrinkage, and estimate the pressure changes due to shrinkage. Hot tearing starts at lower solid fraction when IMCs are present due to reduced interdendritic flow, and hot tear formation is more spatially homogeneous, less clustered and more numerous. We show that the largest, most damaging hot tears form from many merging events, that is enhanced by the presence of IMCs.

Effect of ball milling and subsequent size reduction of graphite flakes on the surface mechanical properties of graphitized Al-1100 alloy

Current study explains about ball milling and subsequent mechanical insertion of graphite particles into aluminium (Al-1100) surface for forming composites on surface through an electrical resistance heat supported pressing procedure. Ball milling of as-received 60 mesh graphite particles was carried out which successfully reduced the particle size. After that surface of the aluminium is coated with ball-milled graphite by solution casting. For impregnation, the interface of graphite/aluminium is locally heated by the assistance of an electrical resistance heating followed by mechanical pushing. Heat generation and thus level of aluminium surface softening can be structured by process factors like current and heating time. SEM, TEM, Raman spectroscopy and XRD were employed for microstructural characterization. Successful impregnation and agglomeration of graphite particles inside aluminium matrix is revealed from microstructural characterization. Impregnated graphite particles when characterized with Raman spectroscopy shows band shifting and increased intensity ratio (ID/IG). Presence of intermetallic compound (Al4C3) was not detected from the XRD and TEM study. Surface and subsurface mechanical characterization was carried out nanoindentation and microhardness respectively. The modified surface while shows an improvement of more than 120 % in mechanical properties, 130 % improvement is also observed in Young’s modulus. The projected method can be utilized as surface modification technique in solid-state by fabricating surface composites fabricated through mechanical insertion of particulate reinforcement at sub-melting temperatures of substrate and under open producing environment.

Study of the Solder Characteristics of IGBT Modules Based on Thermal-Mechanical Coupling Simulation.

The insulated-gate bipolar transistor (IGBT) represents a crucial component within the domain of power semiconductor devices, which finds ubiquitous employment across a range of critical domains, including new energy vehicles, smart grid systems, rail transit, aerospace, etc. The main characteristics of its operating environment are high voltage, large current, and high power density, which can easily cause issues, such as thermal stress, thermal fatigue, and mechanical stress. Therefore, the reliability of IGBT module packaging has become a critical research topic. This study focuses on the damage of power device solder layers and applies heat transfer theory. Three typical solders for welding IGBTs (92.5Pb5Sn2.5Ag, Sn3.0Ag0.5Cu (SAC305), and nano-silver solder paste) are analyzed using JMatPro software to simulate their characteristics. First, a finite element analysis method is used to simulate the entire IGBT module with ANSYS Workbench platform. The study compares the impact of three types of solders on the overall heat transfer of the IGBT module under normal operation and welding layer damage conditions. The characteristics are analyzed based on changes in the junction temperature, heat flow path, and the law of thermal stress and deformation. The findings indicated that under steady-state working conditions, adjacent chips in a multi-chip IGBT module had significant thermal coupling, with a maximum temperature difference between chip junctions reaching up to 13 °C, and a phenomenon of heat concentration emerged. The three types of solders could change the thermal conductivity and heat transfer direction of the IGBT module to varying degrees, resulting in a temperature change of 3-6 °C. Under conditions of solder layer damage, the junction temperature increased linearly with the severity of the damage. In the 92.5Pb5Sn2.5Ag and Sn3.0Ag0.5Cu (SAC305) solders, the presence of intermetallic compounds (IMCs) led to more stress concentration points in the solder layer, with the maximum stress reaching 7.14661 × 107 MPa and concentrated at the edge of the solder layer. The nano-silver solder layer had the best thermal conductivity, and the maximum thermal deformation under the same conditions was only 1.9092 × 10-5 m.

A study on residual stress generation versus recrystallisation in FSW joint of dissimilar alloy pair of the AA5083 and HSLA steel

The distribution of residual stresses across the joint interface of dissimilar joining between AA5083 and HSLA steel by friction stir welding technique was investigated through 2D XRD method and a numerical simulation model. The measured and simulated residual stress distributions are compared and discussed in the context of active recrystallisation mechanism and the possible presence of intermetallic compound (IMC) layers across the joint interface. The active dynamic recrystallisation (DRX) and multiple Fe/Al series IMCs as evident from the EBSD and 2D XRD, respectively critically demonstrated the variation in residual stresses between the experimental and theoretical values. The highest residual stress values of 375 and 281 MPa were recorded for the HSLA steel side and AA5083 side, respectively.

Stainless steel to aluminium joining by interfacial doping with Al2O3 powder in wire arc direct energy deposition process

Joining of stainless steel (SS) to aluminium (Al) through fusion welding process has always been a challenging task for researchers. The evolution of low cost, highly functional SS-Al joint can cater the wide thermal and structural applications. This paper describes the microstructure and mechanical properties of SS-Al dissimilar joints formed by Al2O3 interfacial doping in a wire arc direct energy deposition process with varying heat input. Results revealed direct effect of Al2O3 on the grain refinement up to ∼ 2 µm. The presence of FeAl, FeAl3, and Fe2Al5 at the interface increases with increasing heat input. The presence of intermetallic compounds (IMCs) and grain refinement due to Al2O3 improved interfacial strength up to ∼ 77.5 MPa.

Microstructure and Mechanical Properties Analysis of Al/Cu Dissimilar Alloys Joining by Using Conventional and Bobbin Tool Friction Stir Welding

The feasibility of producing welding joints between 6061-T6 aluminum and pure copper sheets of 6 mm thickness by conventional friction stir welding (CFSW) and bobbin tool friction stir welding (BTFSW) by using a slot-groove configuration at the joining surface was investigated. The microstructure of the welded samples was examined by using an optical microscope and X-ray diffraction. Furthermore, the mechanical properties of the weld samples are compared based on the results of the tensile test, hardness measurement, and fractography test. The slot-groove configuration resulted in the presence of a bulk-sized Al block on the Cu side. The microscopic observations revealed the dispersion of fine Cu particles in the stir zone. The presence of intermetallic compounds (IMCs) CuAl2, which are hard and brittle, lowered the strength of the weld joints. The strength of the weld joints produced with BTFSW was superior to that of the C-FSW. The maximum hardness values of 214 HV and 211 HV are reported at the stir zone for BTFSW and CFSW, respectively. The fracture location of all the joints was at the intersection of the stir zone and the thermomechanically affected zone was on the Cu side.

Characterisation of Sn–3.5Ag solder/Cu joint under various reflow conditions

The effect of reflow time and reflow temperatures on wettability and bond shear strength of Sn–3.5Ag solder alloy on a Cu substrate is assessed for reflow times of 10 s, 100 s, 300 s, 500 s and reflow temperatures of 250 °C, 270 °C, 290 °C, 320 °C. The wetting regime was found to have capillary, gravity, and viscous regimes. A microstructural study using a scanning electron microscope (SEM) with energydispersive spectroscopy revealed the presence of intermetallic compounds at the interface between the substrate and solder droplet. The bond strength of the solder joint is maximum at a reflow temperature of 250 °C and a reflow time of 10 s. Bond shear strength decreased with an increase in reflow time from 10 s to 500 s. The effect of different cooling conditions on the solder–substrate joint is also investigated.

Diffusion welding of CoCrNi Medium-entropy alloy (MEA) and SUS 304 stainless steel using different interlayers

With the emergence of entropy alloys, the scientific community has been persuaded to explore its joining issues for some stimulating and un-explored engineering applications. Currently, CoCrNi Medium-entropy alloy (MEA) is considered to be an excellent cryogenic material which can retain highest strength and ductility even at cryogenic temperature (i.e. 77 K). With such extravagant properties, authors compelled to explore the joining issues of this alloy. Therefore, the motivation of this research was to examine the weldability of CoCrNi MEA with the commercially available SUS 304 stainless steel using different interlayers. This research work was mainly concerned to investigate the effect of Ni, Cu, and Nb interlayers on bond formation and interface reaction during vacuum diffusion welding process. Results clinched that Ni-interlayered joints were free from the formation of Intermetallic Compounds (IMCs) and offered maximum shear strength (425.5 MPa). Cu-interlayered joints displayed the formation of Cr-C IMCs at Cu-SUS interface while Nb-Co, Nb-Ni and Nb-Cr-Ni phases were formed at Nb-MEA side. Formation of microvoids, cracks and presence of IMCs was observed in Nb-interlayered welded samples which caused lowest shear strength (238.12 MPa). Energy dispersive X-ray (EDX) and electron probe micro analysis (EPMA) were used to examine the diffusion thickness, diffusivities of constituent elements and other microstructural features across the welded joints. Scanning electron microscopy (SEM) scans and X-ray diffraction (XRD) was also executed on fractured surfaces to comprehend the joint formation mechanism.

Strong Mo/Cu interfacial bonding facilitated by consumable Ti interlayer

It is challenging to construct interfacial metallurgical bonding in Mo/Cu immiscible system because of the lack of mutual solubility. Here it was demonstrated that such problem can be effectively circumvented and robust Mo/Cu interfacial bonding can be achieved by diffusion bonding at 800 °C using a thin Ti interlayer. At the initial stage, bonding was made by forming MoTi solid solution (s.s) and TiCu intermetallic compounds (IMCs). The presence of IMCs was detrimental to joint integrity, leading to poor bonding strength. Prolonged bonding duration resulted in dilution of Ti and progressive elimination of TiCu IMCs. Ultimately, IMCs free joint exhibiting excellent interfacial bonding strength comparable with Cu base metal properties was obtained at bonding duration of 60 min.

The Extrusion and SPS of Zirconium-Copper Powders and Studies of Selected Mechanical Properties.

Zr-2.5Cu and Zr-10Cu powder mixtures were consolidated in the extrusion process and using the spark plasma sintering technique. In these studies, material tests were carried out in the fields of phase composition, microstructure, hardness and tensile strength for Zr-Cu materials at room temperature (RT) and 400 °C. Fractography analysis of materials at room temperature and 400 °C was carried out. The research took into account the anisotropy of the materials obtained in the extrusion process. For the nonequilibrium SPS process, ZrCu2 and Cu10Zr7 intermetallic compounds formed in the material at sintering temperature. Extruded materials were composed mainly of α-Zr and ZrCu2. The presence of intermetallic compounds affected the reduction in the strength properties of the tested materials. The highest strength value of 205 MPa was obtained for the extruded Zr-2.5Cu, for which the samples were cut in the direction of extrusion. For materials with 10 wt.% copper, more participation of the intermetallic phase was formed, which lowered the mechanical properties of the obtained materials. In addition to brittle intermetallic phases, the materials were characterized by residual porosity, which also reduced the strength properties.

Impurity Distribution During Electrolytic Refining of Antimony

Results of electrolysis of antimony (99.56% Sb) in a sulfate-fluoride electrolyte are provided. Electrolysis parameters and distribution of 20 associated elements between the cathode metal, sludge, and electrolyte are determined. Phase composition of the sludge formed is established, and it is shown that presence of intermetallic compounds (NiSb and NiSb2) in refined metal promotes transfer of nickel into sludge. A balance is provided for antimony and controlled elements (Fe, Ni, As, Pb, Sn) for the electrolysis products. Volumes of electrolyte involved in electrowinning with an insoluble anode and solution utilization are substantiated. A production scheme for preparation of antimony grade Su00 is proposed and established. The scheme includes stages of pyrometallurgical refining, anode casting, electrolysis, electro-winning with an insoluble anode, and deposition of impurities (neutralization). Direct extraction of antimony into cathode metal in the electrolysis stage is 97.9%.

Liquid Metals in Catalysis for Energy Applications

Summary To keep up with the fast-paced transitioning of the global energy sector, which is constantly thriving to enable reliable, economic, and sustainable energy production, catalysis research has been required to continuously evolve in response. The challenges in the existing systems are predominantly due to dependencies on heterogeneous solid catalysts that are susceptible to coking. In this respect, liquid-metal (LM) catalysts have been demonstrated to have a critical advantage over conventional catalysts. Recently, LMs acquired a place in catalysis, with a reputation often synonymous with interesting properties and a remarkable ability to break trade-offs between homogeneous and heterogeneous catalysis. This review bridges the fundamental principles of LM research and the recent advances in LM-based thermal and electrochemical catalysis for energy applications. Moreover, emerging approaches for the improved utilization of LMs are outlined, and the concepts requiring greater research attention that could enable the development of exciting energy solutions are highlighted.

Weldability of Aluminum-Steel Joints Using Continuous Drive Friction Welding Process, Without the Presence of Intermetallic Compounds

Weldability of Aluminum-Steel Joints Using Continuous Drive Friction Welding Process, Without the Presence of Intermetallic Compounds

Study of combined effect of zirconium and titanium on microstructure and mechanical properties of micro-alloyed cast steels

Aim of the present work is to study the influence of zirconium as well as titanium in combinations on the microstructures and mechanical properties of low carbon micro-alloyed cast steels and to compare with non micro-alloyed low carbon steels. The quantum of research work on the zirconium bearing micro-alloyed steels with respect to grain refinement and mechanical properties is scanty. The micro-alloyed steels with 0.05 wt% to 0.10 wt% Zr and Ti were melted by a conventional air induction melting furnace and they were further subjected to normalizing at a temperature of 1000 °C for 1 h followed by cooling in atmospheric air. The metallurgical properties of the heat treated samples were observed by optical microscope and TEM. It is observed that steel with Zr and Ti shows the presence of acicular ferrite with a very fine grain size of around 5–10 microns as compared to the non micro-alloyed steel. In addition, the inter-lamellar spacing of pearlite as well as presence of intermetallic compounds were seen clearly in the heat treated samples by TEM. It is also observed that the presence of precipitates accounts for the improvement of strength and toughness of steels containing micro alloying content in the heat treated condition. The steel with 0.1 wt% Zr + 0.1 wt% Ti content showed tensile strength with nearly two times higher in comparison to steel without micro alloy addition in steel. However the elongation of both steels is almost equal (percentage of elongation is found to be around 36%). This can be attributed due to the presence of zirconium carbo-nitrides causing the formation of fine grains in steel with Zr and Ti contents.

Study of the structure of coating of the copper-clad steel wire obtained by «freezing-out» method

The results of studying the structure of the coating obtained by «freezing-out» method with a preliminary surface preparation including application of the underlayer or precoat by cladding with a flexible tool (CFT) are presented. The CFT procedure consists in coating with a rotating cylindrical metal brush. The developed technology of coating using «freezing-out» with the preliminary application of the precoat makes it possible to exclude harmful and labor-consuming galvanic operations. The effect of technological parameters on the quality of CFT-formed coating, i.e., the structure of the interface between the steel-copper system and data of durometric measurements of the microhardness of the copper layer and the steel core were analyzed. Elastic-stress states in the surface layer of the core and in the copper coating were determined using X-ray tensometry by the method of oblique survey. The effect of the underlayer of various materials (copper, brass, tin, tin-lead alloy) on the adhesion of the main copper coating to the core after «freezing-out» copper was studied using an adhesimeter. A fractographic analysis of the destroyed coating surfaces was also carried out. The distribution of metals in the border zones of the steel-copper compound is determined. Camscan scanning electron microscope and X-ray microanalyzer Link exL are used to examine the zone structure for the presence of intermetallic compounds. The developed «freezing-out» procedure with a preliminary application of the undercoat by CFT method is environmentally friendly, easy to use and low-power-consuming technology.

Microstructure and mechanical behaviour of aluminium-carbon steel and aluminium-stainless steel clads produced with an aluminium interlayer

The influence of an interlayer on the microstructure and the mechanical behaviour of aluminium‑carbon steel and aluminium-stainless steel clads produced by explosive welding was studied. Different series of welds were produced both with and without an aluminium interlayer, testing different welding parameters. The combination of aluminium to carbon steel presented a better weldability than aluminium to stainless steel. For both couples, low-velocity welds presented the best microstructure and mechanical strength. The mechanical tests showed that the aluminium to carbon steel joining did not benefit from the use of the interlayer. A joint with good interfacial morphology and excellent tensile-shear properties was achieved by low-velocity direct welding, with the fracture occurring outside the joining region. For the aluminium to stainless steel couple, the use of the interlayer increased its weldability. However, the mechanical strength of the joint is restricted by the low strength of the interlayer. The presence of intermetallic compounds at the weld interface, does not, by itself, promote the poor-quality of the explosive weld. The way the interface accommodates and distributes these intermetallics dictates the weld's quality.

Effect of TiO2 nanoparticles addition on microstructure and mechanical properties of dissimilar friction stir welded AA6063-T4 aluminum alloy and AZ31B-O magnesium alloy

In this research, dissimilar AA6063-T4 aluminum alloy and AZ31B-O magnesium alloy sheets were joined using friction stir welding (FSW) by incorporating the TiO2 nanoparticles to the interface of weld joints through creating a novel groove design in the faying surfaces in order to prevent nanoparticles dissipation during welding. A process window was acquired to recognize optimal welding parameters and sound welds with appropriate metallurgical bonding and mechanical interlocking were obtained. The applied rotation and travel speeds were varied within 700–900 rpm and 40–60 mm/min, respectively. The variation of heat input played the most important role in microstructure evolution, nanoparticles distribution and formation of Al3Mg2 and Al12Mg17 intermetallic compounds (IMCs). The weld joint fabricated at 800 rpm and 40 mm/min reached the highest tensile strength of 132 MPa which was almost two times higher than nanoparticles-free weld joint indicating the substantial effect of nanoparticles on strengthening. Fine microstructure, presence of IMCs as well as nanoparticles distributed in the stir zone (SZ) were known as the main reason of a significant increase in the microhardness profile that reached the value of 196 HV. Meanwhile, brittle fracture mode was observed for most of the weld joints, while relative ductile fracture signs also existed.