Intermetallic Research Articles

A "Talking" between Gold Nanoparticle and a Luminescent Iridium(III) Complex: A Study of the Effect Due to the Interaction between Plasmon Resonance and a Fluorophore.

This paper explores a novel synthesis and characterization of silica-coated gold nanorods (AuNRs) embedding a highly emissive cyclometalated iridium(III) complex, denoted as Ir1. We investigate the optical properties and the interplay between the metal compound and gold plasmon, observing how the emission of Ir1 incorporated into the nanoparticles shows two emission bands, one in the blue and the other in the green-orange range of the visible spectrum. To obtain a clearer picture of what we were observing, we synthesized analogous nanosystems, from which it was possible to highlight the effect of different features. Based on what we observed, we proposed that the fraction of the iridium(III) complex in direct contact with the surface of the gold nanoparticle undergoes a "demixing" of the excited state, which, for cyclometalated iridium complexes, is generally considered a mixed LC+MLCT state. This preliminary study sheds light on the complexity of the "talking" between a fluorophore and a plasmonic system, highlighting the importance of considering the emitter typology when modeling such systems.

Enhanced mechanical and damping properties of Cu-Modified Al-Ni eutectic alloys: Solid-solution and precipitation hardening effects

The study aimed to analyze the mechanical properties, precipitation strengthening, and microstructure of Al-Ni-Cu alloys to understand their enhanced characteristics. Additionally, the damping behavior was examined using a dynamic mechanical analyzer across a continuous heating temperature range with frequencies from 0.5 to 15 Hz. The experimental results indicate that the Al-Ni eutectic alloy, which exhibits an ultrafine Al3Ni intermetallic fiber-reinforced Al matrix, transitions to a dendritic-ultrafine eutectic composite structure. The Cu-containing alloys exhibit two distinct primary phases: α-Al and Al-Ni-Cu ternary intermetallic compounds. The eutectic matrix transforms from Al-Al3Ni to Al-Al7Cu4Ni, and subsequently to Al-Al2Cu. These microstructural evolutions result in an enhancement of the tensile yield strength from 170 MPa to 440 MPa, with additional hardening achieved through aging-induced precipitation. Moreover, the damping capacity improves with the addition of Cu at elevated temperatures, and there is an increase in frequency dependence. This paper will discuss the microstructural features, mechanical properties, deformation behaviors, and damping properties in detail.

Suppression characteristics of water mist containing alkali metal compounds in natural gas explosions

The natural gas explosion in semi-constrained spaces seriously jeopardize public safety. Water mist containing additive is an important method to reduce the disaster intensity. However, in actual scenarios, the explosion usually propagates for a certain distance before entering the mist area, which is more difficult to suppress the explosion. Therefore, the self-designed experimental system was used to recognize the suppression effect of water mist containing alkali metal compounds under the simulated scenario. The results show that the flame propagation distance was significantly reduced, the shortest overfire range was decreased by 40.0 % compared with the water mist condition. The peak overpressure and pressure rise rate also showed a significant decrease, the maximum pressure drop rate reached 72.3 %. When the explosion flame entered the atomized region, the turbulent disturbance generated by the atomization accelerated the mixture of combustion zone and the unburned area, which increases the possibility of consuming free radicals. Compared with the KCl and NaCl, the mist containing K2CO3 and Na2CO3 share higher suppression capacity. This study provides scientific guidance for the practical application of water mist explosion suppression.

Effect of intermetallic compounds on the mechanical properties of Cu/Al clad sheets with an SS304 interlayer

Annealing treatments were conducted on Cu/Al clad sheets incorporating a 304 stainless steel (SS304) interlayer to investigate the impact of intermetallic compounds (IMCs) on the mechanical properties of these clad sheets with an interfacial layer. Additionally, the mechanisms of interfacial strengthening and crack propagation behavior were examined. It was found that the best overall performance was achieved for samples annealed at 200 °C, showing tensile strength, fracture elongation, and peeling strength values of 219 MPa, 7.19 %, and 19.6 N/mm, respectively. For the rolled clad sheet, cracks typically initiated at the edges of the SS304 fragments, accompanied by minor residual holes and stress concentrations. Post-annealing, the Cu and Al layers underwent varying degrees of recovery and recrystallization, and element diffusion increased, leading to improvements in elongation and interfacial bonding strength of the clad sheets. As the thickness of the IMCs grew, the interfacial crack propagation path shifted to the Al2Cu/AlCu interface within the IMC layer, significantly reducing the bonding strength.

Influence of FSW process on dissimilar T-joint of aluminum alloy to pure copper

ABSTRACT This work investigated the influence of friction stir welding (FSW) parameter on forming the dissimilar T-joint of aluminum alloy 6061 (AA6061) to pure copper (C1100). The experimental outcomes indicated that the hook formation trended to move toward the center of welding line at low welding and/or high rotational speeds. In all cases, the kissing bond (KB) defects were significantly observed in advancing (AS) compared to retreating sides (RS). The thickness of diffusion and intermetallic compound (IMC) layers decreased with increasing welding and/or decreasing rotational speeds. A highest joint efficiency was attained with approximately 74% at 500/125 rev/mm of the skin test and 34% at 500/100 rev/mm of the stringer tests. The fracture process under the stringer test initiated from the AS to the RS along the interface while that of the skin test cracked in the heat affected zone. Improving dissimilar T-joint of AA6061/C1100 was impacted not only by controlling the KB defect but also the IMC layer thickness.

Experimental Investigation of the Influence of Phase Compounds on the Friability of Fe-Si-Mn-Al Complex Alloy

The research presented in the article is devoted to the study of the influence of phase compounds on the friability of the Fe-Si-Mn-Al complex alloy. The urgency of the problem lies in the development of technology for producing a non-scatterable alloy from manganese-containing ores and high-ash coals. The main goal of this work is to determine the range of alloy compositions and the resulting phases that affect the dispersibility of the alloy, which is critically important for its industrial implementation. Research methods include thermodynamic diagram analysis (TDA) using data on the standard enthalpy of formation of intermetallic compounds, as well as experimental tests in an ore-thermal electric furnace with a capacity of 200 kV*A. The results show that Fe-Si-Mn-Al complex alloys form a variety of silicide and aluminide phases, including intermetallic compounds and ternary systems, which is critical for understanding and controlling their physicochemical properties. When melting a complex alloy, the content of leboite (Fe3Si7) in the Fe-Si-Mn-Al system plays a significant role. The development of melting process technology will be aimed at avoiding the FeSi2-Fe3Si7-F2(FeAl3Si2)-Mn11Si19 tetrahedron area. This approach to controlling the composition of a complex alloy is critical to ensuring its consistent friability properties in industrial applications. Thus, this work represents an important step in understanding the physical properties and stability of Fe-Si-Mn-Al complex alloys, which have potential for widespread use in metallurgical and other industrial applications.

Effect of the addition of Ni and Cu on solidification microstructure evolution of Al-5Si-0.5Mg alloys

AbstractTo develop new high-performance hypoeutectic Al–Si–Mg alloys at elevated temperatures, it is often necessary to add alloying elements of Cu and Ni. The high-temperature strength of the most used Al–Si–Mg–Cu–Ni alloy depends on a load transfer from the α-Al matrix to the intermetallic compounds. However, there is still a lack of detailed investigation on the effects of the combined addition of Ni and Cu on the solidification microstructure evolution of Al–Si–Mg base alloys with a lower Si concentration. This investigation specifically addresses the effects of the addition of Cu or Cu and Ni on the solidification microstructure evolution of the Al–5Si–0.5Mg alloy. It was found that when Al–5Si–0.5Mg is alloyed with Cu or Cu and Ni, the solidus temperature decreases, while the freezing range of the Al–5Si–0.5Mg alloy increases. With the addition of Cu and even small amounts of Ni, the phases Al7Cu4Ni and Al5Cu2Mg8Si6 were predicted by TC simulations and also observed by SEM. With a higher Ni content, Al3Ni and Al3Ni2 also solidify. More importantly, the presence of Cu and Ni can partition into the α-AlSiFeMn phase and change the size and morphology of the α-AlSiFeMn phase. This investigation provides a helpful hint to the development of the high-performance Al–Si–Mg–Cu–Ni alloys with a simultaneous improvement of the thermal conductivity and mechanical properties.

Effect of Ni interlayer on microstructure and mechanical properties of Sn-based alloy/steel bimetallic materials via liquid-solid compound casting

Tin-based alloys have been widely used as an excellent bearing material. However, preparing of Tin/steel bimetallic materials with sound metallurgical interfaces has proven challenging. Importantly, a large number of brittle intermetallic compounds inevitably form at the interface, affecting the material's bonding properties. In this study, an electroplated Ni layer was used for the first time as an intermediate layer in Tin/steel bimetallic composites. It solves the problems of steel surface oxidation and poor wettability. Additionally, the introduction of the electroplated Ni layer impedes the formation of brittle phases, thereby improving interfacial bond strength. The results show that the Tin/steel interface of the Ni interlayer consists mainly of a large number of Ni3Sn4 phases rather than the commonly known FeSn2 phase. A thin layer of residual Ni plating also exists between the steel and the diffusion layer. Furthermore, the properties of Ni3Sn4 and FeSn2 phases were calculated using first-principles calculations. A Tin/steel bimetallic interface achieved a maximum shear strength of 58.63 MPa in the presence of the Ni intermediate layer. At that time, the residual thickness of the Ni layer was 1.5 μm, and the thickness of the diffusion layer was 4.8 μm.

Analysis of Structures at the Boundary of Contact Melting Al–Mg–Mn and Zn Based Alloys

The processes of contact melting of the AMg6 (Al-6%Mg-1%Mn) alloy with Zn–Cu–Al solder and the model Zn–Al alloy, as well as the structure of the contact fusion zone, are studied. Samples were obtained in two stages. At the first step, the solder was mechanically applied (tinned) to the surface of the AMg6 plates. Аt the second step, the resulting composite samples were subjected to heat treatment with a varied exposure time in the liquid state. According to the data of metallographic and X-ray diffraction analyses, as well as differential scanning calorimetry, it was shown that already at the tinning stage the active interaction between Zn and Al occurs, which leads to the formation of a developed microstructure in the joint zone. The presence of copper in the solder HTS-2000 reduces the melting point of the Zn-Al alloy by 30-40°C and improves the conditions for contact interaction with the grade AMg6 matrix. Active diffusion of zinc ensures the formation of an extensive melting zone during heat treatment, while zinc-rich areas during crystallization contain the Zn5Cu intermetallic phase, which prevents the formation of intermetallic ZnxMgy compounds, which does not lead to embrittlement of the contact zone.

Study of minor Sc and Zr additions effect on silicon rich Al–Mg–Si aluminum alloy microstructure during Sc multistage thermal treatment

The study addresses the effect of multistage thermal treatment on microstructure formation of Al–Mg–Si series alloy with scandium and zirconium additions in Mg/Si = 0.3 proportion. Basic alloy AlM–Si without Sc and Zr and them modification AlMg1SiZrSc were cast. AlMgSiScZr alloy multi-stage thermal treatment included the following 4 annealing stages –550 °C 8 h + 440 °C 8 h + 500 °C 0.5 h + 180 °C 5 h. For AlMg1Si alloy it was performed following 550 °C 8 h + 180 °C 5 h practice. AlMgSiScZr microstructure was examined using scanning (SEM) and transmission (TEM) microscopy both in as-cast state and after each stage of thermal treatment, for AlMg1Si – both in as-cast state and after final thermal treatment. Coarse intermetallic particles were examined using SEM, while fine particles were examined using TEM. Besides, microhardness values were measured after various thermal treatment stages. It was found out, that coarse intermetallic compounds of Fe2Mg7Si10Al18 type are formed in both alloys during as-cast structure cooling down with such compounds partial dissolution during further thermal treatment. At the same time particles, that can be attributed either to (AlSi)3ScZr or to AlSc2Si2τ-phase, occur in inter-grain boundary of alloys with scandium-zirconium additions. No traces of scandium solid solution discontinuous decomposition have been identified during ingot cooling down. Thermal treatment during 8 h at 550 °C 8 and 8 h at 440 °C results in formation of the phase, which can represent both AlSc2Si2 and Al5SiZr2. At the same time nanoparticles (AlSi)3ScZr do not form during this thermal treatment stage. Heating to 500 °C during 30 min interval allows complete dissolution of magnesium in supersaturated aluminum solid solution. During the final stage β’’ particles (Mg5Si6), representing the major type, form in both alloys; in these conditions scandium does not produce significant effect on their formation.

Boron‐Doped Zinc Oxide Electron‐Selective Contacts for Crystalline Silicon Solar Cells with Efficiency over 22.0%

The exploration of wide‐bandgap metal compound films with excellent passivation and contact properties on crystalline silicon (c‐Si) surface, as alternatives to traditional‐doped Si thin films, holds significant promise for the future enhancement of c‐Si solar cell efficiency. Herein, conductive boron‐doped zinc oxide (ZnO:B) films are deposited by atomic layer deposition (ALD) process and investigated as electron‐selective contacts, in combination with a thin SiOx passivating interlayer. This combination demonstrates a relative low contact resistivity of ≈2 mΩ cm2 and improved passivation quality. Further application of this SiOx/ZnO:B stack as a full‐area electron‐selective passivating contact in proof‐of‐concept n‐type c‐Si solar cells results in a satisfactory power conversion efficiency of over 22.0%. This electron‐selective passivating contact structure, prepared via low‐temperature, simplified, and the compositionally controlled ALD process, offers a promising pathway for the development of high‐efficiency and low‐cost c‐Si solar cells.

What is the true ground state of intermetallic compound Fe3Al?

We discuss recent doubts about the true ground-state (GS) structure of the intermetallic compound Fe3Al. It seems that it should be the D03 structure (observed experimentally), but there are some considerations that, perhaps, D03 might be a high-temperature (>400 K) structure and the GS at 0 K might be the L12 structure because there might be a high energy barrier between both structures and, when the temperature is lowered, the system is not able to transform into the (perhaps) lower-energy L12 structure. To elucidate this problem, we re-interpret our recent extended ab initio electronic structure calculations for Fe3Al performed with the help of the VASP code and using various exchange-correlation energies within the generalized gradient approximation (GGA). Regrettably, some calculations provide the L12 and some of them D03 as the GS structure.To resolve this question, we performed further calculations testing 9 frequently applied metaGGAs, such as TPSS, revTPSS, M06-L, SCAN(-L), rSCAN(-L) and r2SCAN(-L) representing a higher rung of the Jacob's ladder. It turns out that also here some meta-GGAs lead to L12 and some others to D03 GS structure and, again, we cannot decide.In this way, the present results represent the very first step on the way to understand the energetics of the Fe3Al compound and its ground state. We hope they may motivate future theoretical and experimental work in this direction.

Optimizing tool offset in static shoulder friction stir welding of Al6061 to Ti6Al4V for enhanced joint integrity

The precise control of tool offset in static shoulder friction stir welding (SSFSW) is vital for enhancing the mechanical properties and overall effectiveness of dissimilar metal joints. The present study investigates the impact of tool offset on the development of microstructural features, intermetallic compound formation, texture analysis, and mechanical characteristics of SSFSWed Al6061 to Ti6Al4V joints. The results demonstrate that a 2.5 mm tool offset results in an average grain size of 2.65 μm, compared to larger grains of about 4.76 μm and 7.31 μm observed at 2.0 mm and 1.5 mm offsets, respectively. The percentage of low-angle grain boundaries also varies, reaching up to 42.2% at a 2.5 mm offset compared to 48.6% at 2.0 mm and 64.1% at 1.5 mm, indicating enhanced homogeneity in the microstructural properties. Moreover, the ultimate tensile strength at the 2.5 mm tool offset reaches 279 MPa, which is 5.7% higher than at the 2.0 mm offset and 13.4% higher than at the 1.5 mm offset. This improvement is attributed to more uniform distribution of Ti particles over the stir zone. Texture analysis further supports these findings, with the development of alpha fibre at 2.5 mm offset enhancing ductility, thereby underscoring the critical role of tool offset in achieving sound dissimilar metal weldments.

Effects of C content on the microstructure and properties of CoCrFeNiTi0.5Mo0.5Cx high-entropy alloy coatings by laser cladding

In order to deeply investigate the influence mechanism of different contents of non-metallic element C on the microstructure, microhardness, wear resistance and corrosion resistance of high-entropy alloy coatings. CoCrFeNiTi0.5Mo0.5Cx high-entropy alloy coating was prepared on the surface of AISI 1045 steel by laser cladding technology. The results show that the microstructure of CoCrFeNiTi0.5Mo0.5 without C addition consists of FCC phase, BCC phase, intermetallic compound phase and σ-phase structure, and the carbide phases (M7C3 and TiC) start to appear after the addition of C element. The microhardness of the coating increases and then decreases with the increase of C content, and the average hardness is the highest when x = 0.03, 495.3HV0.5, which is 27.6% higher than that of C0. The abrasion resistance of the CoCrFeNiTi0.5Mo0.5Cx high-entropy alloy coatings is gradually increased and then decreased with the increase of C content, and the wear amount decreases from 0.0813 mm3 to 0.0514 mm3, and the main frictional wear mechanisms are adhesive wear, abrasive wear and oxidative wear. With the increase of C content, the corrosion resistance of the coating is gradually improved and then reduced, when the C content is 0.03, the highest corrosion potential is −0.818V, the lowest corrosion current is 1.382E-4 A/cm2, at this time, the passivation film on the surface of the coating is the most stable and dense, with the best corrosion resistance. The results of this paper provide a theoretical reference for the effect of adding non-metallic elements on the microstructure and properties of high-entropy alloy coatings.

Thermal stability of a newly developed Mn containing β-solidifying γ-TiAl intermetallic compound at 750 °C

A newly low-cost β-solidifying γ-TiAl alloy Ti-44Al-3Mn-0.4Mo-0.4W-0.1B-0.1C (in at. %, named as TMMW) was invented. The rolled bars with a diameter of 12 mm were successfully fabricated by conventional hot rolling process, directly carrying out from the ingot without the pre-forging or hot-packing. The heat-treated TMMW rolled bar, which had a fine-grained nearly lamellar (NL) microstructure, was then air-exposed at 750 °C for up to 3000 h. The changes of the microstructure during this exposure were characterized using electron probe X-ray micro-analyzer (EPMA), transmission electron microscope (TEM), electron backscattered diffraction (EBSD) and high-energy X-ray diffraction (HEXRD). The tensile properties of the samples before and after thermal exposure were also tested. The fine-grained NL microstructure is found to be thermodynamically stable during the exposure. Meanwhile, the combined addition of Mo and W shows a positive effect on the stabilization of βo phase at colony boundaries, with only slight precipitation of the nanometer βo phases with no other brittle phases, such as Laves, in the metastable α2 lamellae. It is found that the thickness of the α2 lamellae decreases after 500 h exposure, while remains basically unchanged from 500 h to 3000 h, which is contributed by the effective pinning effect of the precipitated βo phase in α2 lamellae. As a result, the exposure-induced embrittlement under room temperature and elevated temperature does not take place. Interestingly, the ductility tested at 800 °C improves significantly after exposure. As for the tensile strength, it is only reduced by less than 10 % after 500 h exposure, while it remains essentially unchanged when increasing the exposure time from 500 h to 3000 h. Finally, the mechanisms of the precipitation of βo phases in the α2 lamellae and the tensile properties evolution during the exposure were carefully discussed.

Effect of yttrium and oxygen combination on the microstructure of Zr-Cu-Ni-Al metallic glass

The traditional wisdom seems to suggest that yttrium can be added with oxygen to form inert oxides to prevent oxygen contamination during the MGs fabricated process. Here, the effects of yttrium-doped on the microstructure evolution of the Zr-based MG composite coatings were systematically investigated by laser melting deposition technology. We firstly reported that the yttrium oxides were not completely in an inert state, but as the heterogeneous nucleation core with epitaxial growth of the CuZr intermetallic compound with simple cubic structure, under the influence of sufficient heat input and a low cooling rates, while would be inhibited with insufficient thermal input and high cooling rates.

Dissimilar joining of aluminum alloy and low-alloy carbon steel by resistance spot welding

In this work, the resistance spot welding (RSW) process was performed to join aluminum alloy and low-alloy carbon steel plates. The macro characteristics including nugget diameters and indentation rates, microstructure and tensile-shear strength of RSW joints were investigated. The results showed that the nugget of the RSW joints comprises a ‘bowl’ shape nugget on the aluminum side and an elliptical shape nugget on the steel side. Also, the intermetallic compound (IMC) layers containing Fe4Al13 and Fe2Al5 were formed around the aluminum/steel interface with the steel side having a tongue-shape and the aluminum side having a needle-shape. According to metallurgical evaluation and temperature distribution of RSW joints analyzed by the finite element method, the nugget on the aluminum side contained the dendritic grains and equiaxed dendritic grains. The nugget on the steel side consisted of a large amount of bainite and a small amount of coarse lath martensite. The nugget diameters and the indentations rates of RSW joints increased when increasing either welding current or welding time, and decreased when increasing the electrode pressure. The maximum values of nugget diameter and indentation rate of RSW joints were 9.076 mm and 4.144% when using the welding current of 16 kA, welding time of 450 ms and electrode force of 3 kN. In tensile-shear tests, the RSW joints showed a shear-off fracture mode. When increasing the welding current, welding time or electrode force, the tensile-shear strength of RSW joints increased first, and then reached a maximum, and finally decreased. The welding current of 16 kA, the welding time of 300 ms, and the electrode pressure of 3 kN were considered as the optimal welding parameters in the present study which resulted in the maximum tensile-shear strength of 2.24 kN. In addition, the IMC layers of the RSW joints exhibited a uniform and continuous appearance with a thickness of approximately 1.9 μm, and the IMC layer in the central area was thicker than that in the edge area.

Stable and homogeneous intermetallic alloys by atomic gas-migration for propane dehydrogenation

Intermetallic nanoparticles (NPs) possess significant potentials for catalytic applications, yet their production presents challenges as achieving the disorder-to-order transition during the atom ordering process involves overcoming a kinetic energy barrier. Here, we demonstrate a robust approach utilizing atomic gas-migration for the in-situ synthesis of stable and homogeneous intermetallic alloys for propane dehydrogenation (PDH). This approach relies on the physical mixture of two separately supported metal species in one reactor. The synthesized platinum-zinc intermetallic catalysts demonstrate exceptional stability for 1300 h in continuous propane dehydrogenation under industrially relevant industrial conditions, with extending 95% propylene selectivity and propane conversions approaching thermodynamic equilibrium values at 550–600 oC. In situ characterizations and density functional theory/molecular dynamics simulation reveal Zn atoms adsorb on the particle surface and then diffuse inward, aiding in the formation of ultrasmall and highly ordered intermetallic alloys. This in-situ gas-migration strategy is applicable to a wide range of intermetallic systems.

Dispersion, solid solution, and covalent bond coupled to strengthen K4169/TiAl composite brazed joints: First-principles and experimental perspective

Ni/TiAl composite brazed joints could significantly reduce the aircraft's weight. However, low interfacial adhesion, coarse and brittle-hard intermetallic compounds (IMCs) seriously limited the application of Ni/TiAl composite joints in the next generation of aerospace applications. So enhanced K4169/TiAl composite joints were investigated by vacuum brazed with (Ni53.33Cr20B16.67Si10/Zr25Ti18.75Ta12.5Ni25Cu18.75) composite filler metal (CFM) designed based on cluster-plus-glue-atom model. The shear strength of the joint reached 485 MPa, comparable to the 491 MPa of TiAl substrate. The flat and brittle-hard diffusion reaction layer between Zones I and II was eliminated, simultaneously generating CrB4 dispersion strengthening due to the CFM developed with the interfacial solid-liquid space-time hysteresis effect. In Zones II and III, IMCs all transformed into Niss(Cr,Fe)[0–88], Niss(Ti, Al)[004], and Niss(Zr,Si)[11–2] of circular and oval shapes through isothermal solidification. Meanwhile, the residual stresses and hardness were distributed in reticulated cladding characteristics. Thereby, lattice distortion led to solid solution strengthening and increased plastic toughness through crack termination and bridging mechanisms, which inhibited dislocations from plugging and crack propagation. Various interfaces in Zone Ⅳ were regulated into semi- and coherent interfaces. Ni3(Ti,Al)/(Ni,Ti,Al) and (Ni,Ti,Al)/AlNi2Ti were composed of higher interfacial bonding energy (2.771 J/m2, 2.547 J/m2) and Ni-Ni covalent bonds. Interfacial covalent bonding and large interfacial bonding energy coupling strengthened Zone IV. Consequently, cracks initiated at the (Ni,Ti,Al)[013]/Ti3Al[010] and expanded rapidly into TiAl substrate. Therefore, applying this method to design CFMs and regulate the phase, grain morphology, and interface's fine structure could provide new pathways for dissimilar hard-to-join metals.

Dissimilar joining of Ti–6Al–4V to 316L stainless steel by a novel joining process based on arc additive manufacturing and combined twin-wire arc welding

The joining structure of Ti–6Al–4V to 316L stainless steel has potential demands in many fields. However, it is very difficult to avoid the formaiton of intermetallic compounds (IMCs) of the weld between Ti–6Al–4V to 316L stainless steel, which will severely decrease joint properties. In this paper, a novel joining technology that combines the single wire backing arc welding and the spatially arranged combined twin-wire arc welding was utilized to join Ti–6Al–4V and 316L stainless steel. Copper alloy wire (S214) and vanadium alloy wire (V01) were used as filler metals to produce two isolation layers, which prevented the formation of IMCs. The phase compositions at the Fe/Cu, Cu/V and V/Ti interfaces were Fe(S,S) + Cu(S,S), Cu(S,S) + V(S,S) and V(S,S)+(β-Ti, V)SS respectively. The distribution of the spherical and clustered V(S,S) particles in the matrix at the Cu/V interface contributes to dispersion strengthening and solid solution strengthening of the interface. Tensile strength of 394 MPa with an elongation of 2.53% was achieved. The joint fractured at the Cu/V interface of the single wire backing arc weld and the Cu zone of the spatially arranged combined twin-wire arc weld respectively. Dimple plastic fracture modes were detected in the joints. This technology is not only applicable to Ti–6Al–4V titanium alloy/316L stainless steel dissimilar metal joining, but also provides a new research strategy for the joining between other dissimilar metals.