Formation Of Intermetallic Layer Research Articles

Effects of Main Alloying Elements on Interface Reaction between Tool Steel and Molten Aluminum

Effects of Si and Mg as main elements on interface reaction between tool steel and molten Al alloy at 700°C were investigated. Pure aluminum and Al-10mass%Mg alloy showed relatively simple interfacial layers, whereas thicker, multi-layered reaction bonds were found in the diffusion couple of A380 alloy. The diffusion of a large amount of Fe into Al matrix throughout the interfacial layer led to the formation of Al-Fe based intermetallic particles in the Al base metals. The diffusion couple of Al-10mass%Mg alloy showed a similar intermetallic layer as that of pure Al, indicating that 10mass%Mg in the Al melt rarely affected the formation of Al-Fe intermetallic layers. However, A380 alloy showed much expanded soldering area and increased thickness of intermetallic layers. Based on the phase diagram calculated, the solubility of Fe in liquid Al increased significantly with increasing Si content up to apploximately 5mass%, while, in the case of 10mass%Mg addition, the Fe solubility gradually decreased with increasing Mg content. Al-10mass%Mg alloy also showed the same tendency as that of pure Al in the formation and distribution of intermetallic compounds. However, in the Al-12mass%Si alloy, two types of Al-Fe-Si ternary compounds are present on the Al-rich side.

ВЛИЯНИЕ СМЕЩЕНИЯ ИНСТРУМЕНТА ПРИ СВАРКЕ ТРЕНИЕМ С ПЕРЕМЕШИВАНИЕМ НА МЕХАНИЧЕСКИЕ СВОЙСТВА И ОБРАЗОВАНИЕ ЗОН СВАРНЫХ СОЕДИНЕНИЙ АЛЮМИНИЕВОГО И МЕДНОГО СПЛАВОВ

The article examines the effect of welding tool displacement on copper and aluminum during friction stir welding on the formation of microstructure and mechanical properties of a dissimilar weld. The corresponding welding modes were considered in the work: welding tool rotation speed 900 rpm, welding speed 25 mm/min, mixing varied from 0 to 3 mm for copper or aluminum. The most optimal displacement during friction stir welding was the location of the pin of 0.5 and 1 mm on copper, which allows the formation of a composite structure of the core and the thermal deformation zone. At these positions of the tool pin relative to the line of contact of the metals, the mechanical properties of the weld are closer to those of the most ductile material (aluminum). The welding mode parameter (displacement) affects the formation and volumetric content of intermetallic layers. If the thickness of the intermetallic layers does not exceed 4-5 µm, then increased values of the mechanical strength of the welded dissimilar joint are observed.

Characterizing of a unique Al/Cu FGMMC fabricated via the ARB-CRB process followed by annealing

This study investigates the influence of different annealing temperatures on the microstructure and growth of the intermetallic phase in an Al/Cu functionally graded metal matrix composite (FGMMC ( produced by the accumulative roll bonding (ARB)-cold roll bonding (CRB) process. SEM images show the evolving distribution of Cu content in the composite, with the finest and thinnest Cu layer observed in the Al/20Cu region. The annealing at 400°C and 450°C for 2, 4, and 6 hours results in the formation of intermetallic layers (Al2Cu, Al4Cu9, and AlCu) with a clear progression from the Al side to the Cu side, as confirmed by SEM-EDS and TEM analysis. Increasing the annealing conditions increases the thickness of the intermetallic layers. In addition, the intermetallic layers are thicker in the FGMMC sample than in the ARB sample under the same conditions due to the additional strain during the process. The findings demonstrate that a diffusion-controlled mechanism governs the growth of the Al2Cu, Al4Cu9, and AlCu layers. The tensile test results indicate that as the Cu content increases from 20 wt% to 80 wt%, the ultimate tensile strength of the layers increases from 288.24 MPa to 373.66 MPa, while the elongation decreases from 8.2 % to 5.3 %. After annealing, however, these values decreased due to the restoration phenomenon and intermetallic formation. The fracture surface predominantly exhibits a brittle mode, especially with increasing Cu content and annealing conditions.

Friction Stir Welding between Marine Grade Aa 5083 and HSLA Steel

The revolutionary method of solid-state joining technique has already attracted significant attention of advance welding and joining research community. The technique has been continuously developing for many alloy systems for similar and dissimilar joints. Recent research in these areas aiming to join complex dissimilar alloy pairs, composite, polymers, ceramics etc. This paper presents a study of friction stir welding between marine-grade aluminum alloy AA 5083 and HSLA steel, configured in a butt arrangement. The study investigates the evolution of Fe-Al series of intermetallic layer formation at the joint interface and its effective management to yield best joint efficiency. The FSW in the said alloy pairs yielded an 83.25% welding efficiency based on the aluminum alloy side strength. XRD analysis along with SEM examination revealed the formation of Al13Fe4 and Al5Fe2 as intermetallic compounds which was confirmed by the EBSD analysis. The obtained results are discussed in the paper considering the effect of the weld joint performance.

Influence of carbon nanotubes on the morphology of Cu6Sn5 in Cu/(Sn–Ag–Cu) solder joints

This study delves into the intricate interaction between multi-walled carbon nanotubes (MWCNTs) and the Sn–Ag–Cu solder system, highlighting its relevance in lead-free soldering applications. Reflow and isothermal aging induce the formation of intermetallic layers at the joint interface, including Cu6Sn5, Cu3Sn, and irregularly shaped Ag3Sn particles. The addition of MWCNTs leads to the flattening of Cu6Sn5 grains, restraining their growth and potentially improving mechanical strength. Notably, MWCNTs exhibit a relatively high affinity with Ag3Sn. Grain size distribution analysis indicates that MWCNTs reduce particle size, effectively suppressing intermetallic compound growth. Over time, grain size increases due to simultaneous coarsening and growth during isothermal aging. In the growth kinetics analysis of intermetallic compounds in SAC305-MWCNTs solder joints, stable behavior is observed for Cu3Sn growth, driven by solid-state diffusion between Cu6Sn5 and Cu. In contrast, Cu6Sn5 exhibits significant variations in growth behavior with temperature changes. Furthermore, the evaluation of activation enthalpy for Cu3Sn growth in the Cu/(SAC305-MWCNTs) and Cu/SAC305 diffusion couples reveals similar n and k values of the power function for the layer growth, indicating a comparable rate-controlling process for Cu3Sn growth. The presence of MWCNTs in the solder does not significantly influence the rate-controlling process or activation enthalpy for Cu3Sn growth, contrasting with the observed effects on Cu6Sn5 growth. This study provides valuable insights into the interactions within the SAC305-MWCNTs solder system, offering significant implications for lead-free soldering applications.

Experimental and numerical analysis of intermetallics in Al–Mg friction stir welds

In this research work, it was aimed to analyse the thermal behaviour during FSW in order to understand the diffusion behaviour of Al (AA6061)-Mg (AZ31B) dissimilar joints. Three heat input levels at different weld pitch ratios (WPR) of 0.087, 0.068 and 0.051 are accounted for the analysis. Finite element modelling (FEM) is employed to predict temperature evolutions. From the FEM results and fundamental diffusion equations, the intermetallic thickness and the diffusion behaviour between the Al and Mg material were analyzed and found that the Al-rich intermetallic phases Al3Mg2 grow faster and wider than the Mg-rich phase Al12Mg17. Tensile test demonstrates that a lower welding pitch ratio (WPR) leads to the formation of thicker intermetallic layers, resulting in reduced tensile strength and joint efficiency. In contrast, a higher WPR (0.087) minimizes intermetallic thickness, yielding superior tensile properties (138mpa). Microhardness measurements at the stir zone reveal a broad range from 70 to 164 HV, signifying mechanical heterogeneity. Microstructural reveals that a complex interplay between Al and Mg materials, resulting in fine equiaxed grains, intermetallic compounds, and distinct flow patterns in the stir zone.

Enhancing Microstructural, Textural, and Mechanical Properties of Al-Ti Dissimilar Joints via Static Shoulder Friction Stir Welding

Abstract The present study explores the application of static shoulder friction stir welding (SSFSW) to address the challenges of poor mechanical properties in conventional Al-Ti dissimilar friction stir joints, which arise due to significant material mixing and the formation of thick intermetallic layers. The results show that SSFSW inhibited material mixing and the mutual diffusion of Al and Ti were suppressed due to lower heat input. Mutual interdiffusion of Al and Ti was directed by an exothermic chemical reaction, forming an Al5Ti2 – Al3Ti sequence due to sluggish diffusion of Al in Ti at a temperature of 512°C achieved in this study. The microstructure at stir zone (SZ) comprised equiaxed grains with Ti particles acting as dispersoids for nucleation, whereas the presence of large Ti blocks at SZ of Conventional FSW (CFSW) resisted plastic deformation, resulting in non-homogeneous concentration of dislocations near its interface. A significant decrease in grain size at all the critical zones of weldment was due to rearrangement of dislocations through slip-and-climb mechanism, as evidenced by the occurrence of dynamic recrystallization. Emergence of γ-fiber and basal fiber texture increased the tensile strength of SSFSW to 289 MPa, which is about 11.2% higher than CFSW, with joint efficiency of about 88%. The study also analysed the contribution of various strengthening mechanisms to the yield strength improvement of SSFSW weldments in detail of SSFSW weldments in detail, and the results showed that grain boundary strengthening contributed the most to strength improvement in SSFSW.

Growth behavior of intermetallic layers at the interface between Cu and eutectic Sn–Bi by grain boundary diffusion with the grain growth at solid-state temperatures

The growth kinetics and rate-controlling processes of intermetallic layers formed in Cu/(Sn-58 wt% Bi) diffusion couples were investigated. Isothermal annealing of diffusion couples was conducted in the temperature range of 363–393 K for various times up to 384 h. In the diffusion couple, an intermetallic layer composed of Cu6Sn5 with irregular scallop shapes and Cu3Sn with relatively uniform thickness forms at the Cu/(Sn–Bi) interface. Isothermal sections of the equilibrium phase diagram in the ternary Bi–Cu–Sn system were calculated at the isothermal annealing temperatures and the peak temperature of the reflow process by a CALPHAD (calculation of phase diagrams) method. The diffusion path passes through the three-phase tie-triangle, including Cu6Sn5 and Cu3Sn. The obtained thicknesses were plotted against the annealing time, and a power function equation was found to describe their relationship. The values of the exponent in the power function were close to 0.25, indicating that the layer growth was predominantly controlled by boundary diffusion with the grain growth. Furthermore, the exponent values were relatively insensitive to the annealing temperature. The relationship between the exponent and the annealing temperature was analyzed, and it was concluded that the grain growth in the intermetallic layer followed a parabolic law. The growth and morphology evolution of the intermetallic compound and Sn–Bi eutectic microstructure at the interface were depicted, shedding light on the widening of the eutectic microstructure. Additionally, the activation enthalpy for the rate-controlling process of intermetallic layer growth at solid-state temperatures was evaluated using a least-squares method, providing insights into the energy barrier for the diffusion or transport of atoms across the interface. This study contributes to a better understanding of intermetallic layer formation and growth in Cu/(eutectic Sn–Bi) diffusion couples, offering valuable information for developing reliable solder joints and high-temperature solders.

Evaluation of dissimilar 7075 aluminum/AISI 304 stainless steel joints using friction stir welding

Friction stir welding of dissimilar 7075 aluminum/AISI 304 stainless steel joints was done using different tool rotational speed values. The weld was mainly formed in the aluminum part due to the offset value, and stainless steel particles were surrounded with the stirred fine-grained Al matrix. Intermetallic compounds consisting of FeAl3, Fe3Si, FeAl, Fe4Al13 and Fe3Al2Si4 were found in the weld bead. The thickness of the intermetallic compound layers was increased up to 6 µm by increasing the tool rotational speed. Moreover, the stir zone was mainly characterized by a composite-like structure. The weld strength was increased significantly by decreasing the tool’s rotational speed. The maximum strength of joints was about 72% of 7075 aluminum strength. The formation of extensive intermetallic compound layers could be the reason for the reduced joint strength. In specimens with higher tool rotational speeds, fracture occurred within the stir zone.

Corrosion mechanism of reduced activation ferritic martensitic steel JLF-1 in liquid metal Sn

Reduced activation ferritic martensitic steel JLF-1 (Fe-9Cr-2 W-0.1 C) corroded in liquid Sn at 673–873 K due to the formation of intermetallic compound layers. The outward growth of FeSn2 layer at 773 K was rate-controlled by a boundary diffusion. The inward growth of FeSn-like layer was recognized in the exposure for more than 250 h. The FeSn growth progressed according to the diffusion of Sn along the boundaries of martensite structure. Thin Cr2O3 layer formed by a pre-oxidation treatment did not function as an anti-corrosion layer in liquid Sn, though the sintered specimens of Fe2O3 and Cr2O3 revealed corrosion resistance.

Distribution of intermetallic compounds in dissimilar joint interface of AA 5083 and HSLA steel welded by FSW technique

Multi-material design concept is growing rapidly in association with the advancement of dissimilar alloy joining technology implementing FSW technique. In this paradigm, the major concern in joining Al alloys to steel by FSW technique, is to manage the intermetallic layer formation. In this context, knowing the types of Al-Fe series IMCs and their distribution is an important aspect for determining the joint performance. The present research thoroughly examined the interface region of the dissimilar welded joint between AA5083 and HSLA steel fabricated by FSW technique in butt configuration. The joint interface was deeply investigated by XRD, EBSD, TEM and APT studies to explore the distribution pattern of the various type of Al-Fe intermetallic compounds across the joint thickness. The study identified from the inverse pole figure (IPF) maps the presence of Al rich IMCs Al6Fe and Al13Fe4, in Al side and Fe rich phases AlFe and AlFe4 in steel side. A massively recrystallized microstructure with ultrafine grains of order ∼1 μm in diameter and a misorientation of 0.82 high angle grain boundary (HAGB) fraction were observed at the interface along with the aforesaid IMCs. Overall, the EBSD along with TEM study depicted that the distribution of Al13Fe4, Al5Fe2, Al9Fe2 and AlFe intermetallic in the microstructure of the interface mainly due to the typical CDRX and DDRX process occurs during FSW. The dominance of HAGBs are found to be the potential factor for diffusion of Fe in Al and vice-versa and which in turn influenced the type and distribution of IMCs across the interface. Moreover, the APT data analysis was successful to explain the atomic mixing pattern by the FSW process and typically Fe rich fragments of AlFe IMC phase was discovered from the reconstruction image and the proximity histogram.

Influence of frictional heat spread pattern on the formation of intermetallic layers at the dissimilar FSW joint interface between AA 5083 and HSLA steel

The dissimilar weld interface for the AA5083 and HSLA steel alloy pair made by FSW technique was investigated to explore the impact of the friction heat flow across the thickness on the types and nature of IMC layer. The detail transmission electron microscopy (TEM) and atom probe tomography (APT) were performed to characterize the IMCs at different layer thicknesses and compositional mixing patterns of the interface. Also, a 3D moving heat source thermomechanical model was developed to simulate the FSW joining of Fe/Al alloy pair and explored the existence of heat flow pattern along the sheet thickness. The detail analysis of SAED pattern obtained from TEM bright field images was conducted to characterize the presence of types and nature of IMCs at different layer thicknesses. In this study the proximity histogram data from APT were investigated for further confirmation of existence of observed Fe/Al IMCs and atomic mixing pattern at the interface. The study identified the presence of Fe2Al9, Fe4Al13 and FeAl6 which are distinctly distributed over the thickness. The relative richness of Fe and Al in these IMCs are found significantly influenced by the thermal gradient in turn typically control their distribution over thickness. The Al rich IMCs such as FeAl6, possessing large ΔGf and low activation energy, found away from the frictional surface of heat source. While Fe rich IMCs form with relatively lesser ΔGf and higher activation energies are seen near the frictional surface of heat source.

Структурные особенности и технология получения легких броневых композиционных материалов с механизмом локализации хрупких трещин

Introduction. Monometallic armor traditionally used in military and special equipment armaments has a number of key disadvantages that have a significant impact on the tactical and technical characteristics of the products, namely, significant weight and thickness. At the same time, composite non-metallic armors, which have been widely used recently as an alternative, in turn, are not able to withstand multiple hits in local areas of the structure due to its complete destruction or delamination. The purpose of the work: to develop the technology of obtaining a new class of multilayer metal armor materials based on light metals and alloys by explosive welding, combining high indicators of bullet resistance and structural strength along with low specific gravity. The work presents a new scheme for reinforcing the composite using explosive welding technology, which allows localizing the development of brittle cracks along interlayer boundaries with external ballistic impact on the object. Results and discussion. Reinforced composite material based on titanium and aluminum alloys is obtained by explosive welding. Rational modes of shock-wave loading, which ensure production of composite material of required quality are determined; evaluation of strength of composite is carried out. In order to improve the tactical and technical characteristics of the composite, it was proposed to form high-solid intermetallic layers in its structure due to heat treatment. Rational modes of high-temperature annealing are defined, which ensure formation of intermetallic layers of preset thickness in composite structure. The phase composition of intermetallic pro-layers is studied. Structural features of the composite material are investigated. Mechanism of brittle cracks localization in composite structure at ballistic impact on it is described.

The influence of surface on direction of diffusion in Al-Fe clad material

Aluminium-steel clad composite was manufactured by twin-roll casting. An intermetallic layer of Al 5 Fe 2 and Al 13 Fe 4 formed at the interface upon annealing above 500 °C. During in-situ annealing in transmission electron microscope, the layer grew towards the steel side of the interface in tongue-like protrusions. A study of furnace-annealed samples revealed, that the bulk growth of the interface phase proceeds towards the aluminium side. The growth towards steel is a surface effect that takes place simultaneously with the bulk growth towards aluminium. At the beginning of the intermetallic layer formation diffusion of Fe into aluminium prevails, afterwards Al atoms diffuse throught the newly formed intermetallic layer towards steel and the whole interface shifts towards aluminium. The kinetics of growth of the intermetallic layer follows parabolic law in both cases, indicating that the growth is governed by diffusion. • In Al-steel clad material intermetallic layer grows towards Al in bulk material. • During in-situ heating in TEM layer grows towards steel. • Steel-facing layer is a surface phenomenon. • Growth of the intermetallic layer follows parabolic law.

Corrosion resistance and metallurgical behaviour of CMT welded Al-LCS dissimilar butt joint exposed in simulated industrial environment

Cold Metal Transfer welding is a predominant process for joining the Aluminium and Low Carbon Steel (LCS) dissimilar joints with enhanced properties. In addition, these joints have vast application in various simulated industrial environmental conditions. However, the formation of thick intermetallic layers during welding over these joints leads to invoking the corrosion attack and causing a catastrophic failure that is the primary concern in life prediction of the joint. Hence, the corrosion behaviour of AL-LCS dissimilar butt joint exposed in the simulated industrial environment has been studied experimentally and it has been compared with the Cold Metal Transfer (CMT) welded aluminium and LCS similar joints. The potentiodynamic polarization and the electrochemical impedance spectroscopy were carried out in 3.5% aggressive sodium chloride medium with varying benzotriazole corrosion inhibitor with varying the concentrations like 10 ppm, 15 ppm and 20 ppm. The results showed that the corrosion resistance behaviour of CMT welded dissimilar joints are increased with increasing inhibitor concentration. The inhibitor showed effective performance, and the efficiency is also found to be 78–80% at 20ppm, which revealed the enhanced corrosion resistance of dissimilar metal joints in simulated industrial conditions. Finally, the dissimilar joints are characterized by sophisticated analytical techniques.

Influence of Friction Stir Welding Modes of Copper and Aluminum Alloys

The article discusses the influence of the parameters of friction stir welding modes on the formation of the outer surface of the weld and the thickness of the intermetallic layer for the thickness of the welded samples of 3 mm. Changing the rotation speed from 600 rpm to 1000 rpm of the welding tool allows you to control the amount of energy input to transfer the welded material into a superplastic state. The welding speed was varied from 20 mm/min to 80 mm/min. The most optimal mode was for an aluminum and copper alloy with a thickness of 3 mm, a rotation speed of 900 rpm, a welding speed of 25 mm/min, an angle of inclination of 30 at which the mechanical properties of the welded seam approached the most plastic material (aluminum). The article considered thermal cycles measured near the pin from the side of the aluminum and copper alloy. The maximum temperature was 900 K on a copper alloy. The parameters of welding modes also affect the formation of intermetallic layers. If the thickness of the intermetallic layer does not exceed 4-5 μm, then increased values of the mechanical strength of the welded dissimilar joint are observed.

Influence of Fly Ash Geopolymer Ceramic Powder Addition on Sn-3.0Ag-0.5Cu Solder Joints

This paper reports the effect of 1.0 wt.% fly ash (FA) geopolymer ceramic powder addition in Sn-3.0Ag-0.5Cu (SAC305, in wt.%) solder joint. Powder metallurgy route was used to fabricate the new composite solder. Solder balls were formed from the new composite solder and reflowed on Cu substrate. The effect of FA as ceramic reinforcement on the bulk microstructure and the interfacial intermetallic compound layer formation of solder joints were investigated under optical microscope. Microstructure observation showed that the β-Sn dendrite size was refined in SAC305-1.0FA/Cu bulk solder joint sample than that in the non-reinforced sample. The addition of FA geopolymer ceramic powder into the solder matrix also produced a thinner intermetallic compound layer.

Feasibility of a laser powder bed fusion process for additive manufacturing of hybrid structures using aluminum-titanium powder-substrate pairings

The state of the art in the thermal joining of aluminum and titanium sheets in butt or overlap joint configuration specifies that the titanium should remain in the solid state to limit the formation of a brittle intermetallic compound layer in the interface. In this study, aluminum samples were additively manufactured onto titanium substrates and vice versa titanium samples onto aluminum substrates using a standard commercial laser powder bed fusion machine. The influences of the energy density during the process on the sample porosity, the characteristics of the interface between sample and substrate, as well as the tensile strength are analyzed. Despite the melting of both materials, a great potential for high interfacial tensile strength has been found for laser fusion of titanium powder on aluminum substrates.

Resistivity and Formation of Intermetallic Layer in Aluminum-Steel Clad Strip

Cladding of two dissimilar materials such as aluminum and austenitic steel can bring outstanding material characteristics beyond the ones of each conventional monomaterials. The study focused on development of an Al-Fe-rich intermetallic phase formed on the aluminum/steel interface during heat treatment. Electrical resistivity measurements were performed to monitor diffusion processes and phase transformations during isochronal and isothermal annealing. Resistivity measurement results were supplemented by microscopic methods revealing the interfacial microstructure.

Fiber laser welding of Ti–6Al–4V to Inconel 718 bimetallic structure via Cu/Ta multi-interlayer

In current work, we have used fiber laser welding (FLW) technology to manufacturing the Ti–6Al–4V (TC4) and Inconel 718 (IN718) bimetallic structure and to prevent the formation of brittle phases via Cu/Ta multi-interlayer. The results of this study showed that Cu/Ta multi-interlayer was very effective in preventing the formation of continuous brittle intermetallic layers of Ti–Ni and Ti–Cu. The good metallurgical bonds were presented at these interfaces between TC4 and IN718. As a result, the joints with gradational structure, i.e. TC4| (α+β Ti, Ta)ss| (β Ti, Ta)ss| Ta(s, s)+ (Cu(s, s)+ Ta(s, s)+ Ti3Ni4)| Cu(s, s)+ (Cu(s, s)+ Ta(s, s))| Ni(Ta, Fe, Cr)ss| IN718 can be formed, which can contribute high tensile strength of joints with the value of 396 MPa.