Metallurgical Bond Research Articles

Directed Energy Deposition-Laser Beam of Semi-Austenitic Precipitation-Hardening Stainless Steel

Directed Energy Deposition-Laser Beam (DED-LB) is an ideal Additive Manufacturing (AM) process to obtain very complex geometries, which can be important for several applications in industries such as aerospace and biomedical engineering. The present study aims to determine optimized DED-LB parameters for printing 17-7 PH stainless steel, a semi-austenitic precipitation-hardening alloy renowned for its exceptional combination of high yield strength, toughness, and corrosion resistance. The experimental work used different combinations of laser power, scanning speed, and powder feed rate to investigate the effects on the morphology, surface roughness, and microstructure of the deposited material. The results indicated that a powder feed rate of 4.7 g/min yielded uniform beads, reduced surface roughness, and increased substrate dilution, enhancing the metallurgical bond between the bead and substrate. Conversely, higher feed rates, such as a rate of 9.2 g/min, resulted in increased surface irregularities due to an excessive amount of partially melted powder particles. Microstructural analysis, supported by thermodynamic calculations, confirmed a ferritic–austenitic solidification mode. The austenite and ferrite fractions varied significantly, depending mainly on the substrate dilution due to the decrease in aluminum content. The combination of 400 W laser power and a 2000 mm/min scanning speed resulted in the optimal set of parameters, with an approximately 30% dilution and 80% austenite.

Bonding mechanism between the AlN ceramic matrix and the copper-based metal cladding layer

Abstract High-temperature brazing and laser cladding methods can form a good metallurgical bond between ceramics and copper cladding. Herein, through these two methods, the preparation of a Cu-based metal cladding layer on the surface of aluminum nitride (AlN) ceramics was carried out. Scanning electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, and other characterization techniques were employed to observe the macroscopic and microscopic morphologies, elemental distribution, and microstructure characteristics of Cu-based metal coatings and transition layers, in order to analyze the interface bonding mechanism. Research has found that the active element titanium (Ti) has a significant promoting effect on the wettability of Cu powder on the surface of ceramics. Metallurgical reactions occur at the interface between ceramics and Cu-based metal coatings. Al and N elements in ceramics react with most of the Ti in the metal coating and Cu in the molten metal also reacts with Ti, generating new compounds, thereby forming a metallurgical bond between ceramics and Cu coatings.

Exploring the implications of CoCrFeNiCu high entropy alloy coatings on tribomechanical, wetting behavior, and interfacial microstructural characterizations in microwave-clad AISI 304 stainless steels

Abstract The exploration of high-performance coatings is specifically necessary for enhancing the mechanical, thermal, and corrosion-resistant characteristics of structural steels in response to the demand for cutting-edge materials in engineering applications. The current study addresses an existing void in the development of durable coatings that gain benefits from the distinctive characteristics of CoCrFeNiCu high entropy alloys (HEA) for stainless steel substrates, with a particular emphasis on SS 304. The primary objective was to examine the microstructural, mechanical, and corrosion behaviors of SS 304 that had been coated with CoCrFeNiCu HEA employing a microwave cladding process. HEA particles were prepared through mechanical milling, and a controlled cladding process was conducted under an inert environment. A variety of meticulous investigations, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and wear rate measurements, have been performed to thoroughly assess crucial parameters, including surface hardness, resistance to corrosion, and wear behavior. This study explores the influence of a CoCrFeNiCu high entropy alloy (HEA) coating (20 % each component) on SS-304 steel. Utilizing microwave cladding, the coating demonstrated a substantial impact on wetting behavior, interfacial microstructure, hardness, and corrosion resistance. Surface hardness was substantially enhanced by the cladding process, resulting in a 54.76 % rise from 210 HV to 325 HV. This enhancement substantially raised the mechanical strength of the steel. Under 120 h of corrosion testing in 3.5 wt.% NaCl, a minimal weight loss of 0.342 mg was observed, suggesting that the material exhibited substantial corrosion resistance. In addition, the material’s capacity to resist abrasive forces has been demonstrated by the relatively minimal wear rate of 0.0012 mm3/m that was noticed throughout wear resistance experiments. Effective interfacial adhesion, bonding strength, and uniform distribution were observed by the coating, which resulted in enhanced mechanical characteristics and durability in harsh circumstances. Wetting characteristics indicated enhanced hydrophobicity/hydrophilicity compared to the uncoated surface. SEM images displayed a well-adhered, homogeneous interfacial region, signifying a robust metallurgical bond. The cladding surface exhibited a uniform distribution of CoCrFeNiCu HEA particles. Notably, the steel’s surface hardness increased by approximately 54.76 % postdeposition. These findings underscore the potential of CoCrFeNiCu HEA coatings in advancing steel surface properties for improved performance and durability. The potential of CoCrFeNiCu HEA coatings to enhance the performance and longevity of SS 304 steel in chemical, marine environments, etc., applications that necessitate superior resistance to wear, protection against corrosion, and structural or mechanical integrity is underscored by these findings.

Microstructure and Electrochemical Corrosion Behavior of Laser Cladding (CoCrNiFeMo)91.5B6.0Si2.5 High‐Entropy Alloy Coating on TC4 Titanium Alloy

(CoCrNiFeMo)91.5B6.0Si2.5 high‐entropy alloy (HEA) coatings are deposited on TC4 titanium alloy by laser cladding, and their microstructure and properties are investigated. The findings indicate that FCC1 and FCC2 are dendritic and euqiaxed structures, respectively, and that HEA coatings form a FCC + σ eutectic structure. A strong metallurgical bond and a high density interface fusion layer are created at v = 1200 mm min−1, and the laser energy density matches that of the cladding. The thermodynamic criteria for the FCC + σ eutectic phase in HEAs created by the nonequilibrium solidification are proposed as follows: δ ≤ 8.5%, 6.88 ≤ VEC ≤ 8, −17 ≤ ΔHmix ≤ 7 kJ mol−1, and PSFE ≥ 40 at%. The thermodynamic parameters of HEACs are as follows: δ = 8.46%, ΔHmix = −10.282 kJ mol−1, VEC = 7.2, and PSFE = 43 at%, which meet the criteria. The coating's cross‐sectional hardness gradually drops from HEA‐coating‐zone, fusion‐zone, heat‐affected zone, and TC4 matrix. When v = 1200 mm min−1, the HEA‐coating‐zone has the highest mean microhardness (830.96 HV1.0). HEA coatings have a double passivation zone with the highest Ecorr (−0.1774 V) and a much lower Icorr (0.047 μA cm−2) than that of other scanning rates. Its FCC + σ eutectic structure, greater crystallinity, improved passivation effect, more dense microstructure, and fewer lattice and grain boundary defects all work together to provide its exceptional electrochemical corrosion performance.

Interface Optimization and Thermal Conductivity of Cu/Diamond Composites by Spark Plasma Sintering Process.

Cu/Diamond (Cu/Dia) composites are regarded as next-generation thermal dissipation materials and hold tremendous potential for use in future high-power electronic devices. The interface structure between the Cu matrix and the diamond has a significant impact on the thermophysical properties of the composite materials. In this study, Cu/Dia composite materials were fabricated using the Spark Plasma Sintering (SPS) process. The results indicate that the agglomeration of diamond particles decreases with increasing particle size and that a uniform distribution is achieved at 200 μm. With an increase in the sintering temperature, the interface bonding is first optimized and then weakened, with the optimal sintering temperature being 900 °C. The addition of Cr to the Cu matrix leads to the formation of Cr7C3 after sintering, which enhances the relative density and bonding strength at the interface, transitioning it from a physical bond to a metallurgical bond. Optimizing the diamond particle size increased the thermal conductivity from 310 W/m K to 386 W/m K, while further optimizing the interface led to a significant increase to 516 W/m K, representing an overall improvement of approximately 66%.

Laser cladding Al/Ni composite coating and its tribology performance

Al/Ni coating was prepared on Al substrate by laser cladding technology. The effects of Al/Ni ratio on the morphology, phase composition, hardness and wear resistance of the coating were investigated. The results showed that the coating formed a strong metallurgical bond with 7075 aluminum alloy substrate. With the increase of Ni content, the microstructure at the top of the coating changes from plate dendrites to equiaxial dendrites. When the Ni content reaches 50%, the top of the AlNi50 coating is a sheet of Al-Ni intermetallic compounds and locally precipitated Al-Ni intermetallic compounds with high aluminum content. The intermediate structure of the coating is dominated by columnar dendrites, and the heat-affected zone (HAZ) is characterized by transverse equiaxial dendrite structure. With the increase of Ni powder in composite powder, the hardness and wear resistance of the coating increases correspondingly. In particular, the maximum hardness of the AlNi50 coating is 1050 HV 2 , which is about 7 times the average hardness of the substrate. The wear surface of the AlNi50 coating has a shallow gully, the friction coefficient is only 0.305, and the wear amount is only 4.5 mg within 60 min. The corrosion potential of AlNi50 is −1.0838 V, the corrosion current density is 3.672 × 10 −5 A/cm 2 , and the corrosion resistance is better than that of the substrate.

INTERDIFFUSION ZONE CHARACTERISTICS OF INTERFACE BIMETAL ALUMINUM-COPPER PRODUCED BY SQUEEZE CASTING

Bimetals are metallurgical bonds formed by the mixing of two materials. One method of producing bimetal is through squeeze casting. However, there is currently no established optimal pressure reference for the pressing during bimetal production. This research aims to determine the optimal pressure in the form of bushings to achieve an optimal interdiffusion bond at the interface. The study uses copper and aluminum alloys. The melting temperature of the aluminum is set at 770°C, while the copper is 1150°C. The molten metals are alternately poured into a mold. In the first stage, aluminum is poured into the mold, followed by copper in the second stage, gradually forming an aluminum-copper bimetal bushing. In the third stage, pressure is applied. The squeeze pressure variations used are 30, 40, 50, and 60 MPa. The results show that increasing the squeeze casting pressure leads to an increase in the thickness of the interdiffusion layer. The highest hardness is observed in the interface because of the formation of AlCu compounds. The increase in hardness also enhances wear resistance in the interface. Therefore, squeeze casting with a pressure of 60 MPa is recommended for producing Al-Cu bimetal to achieve optimal interdiffusion at the interface.

Wire-arc directed energy deposition of steel onto tungsten substrate: fabricability and mechanical performance of synergistic structures

ABSTRACT This study investigates the fabricability, microstructures, and mechanical properties of multi-material structures composed of W7Ni3Fe tungsten alloy and SS316L stainless steel using a wire-arc directed energy deposition process. Direct deposition of SS316L onto W7Ni3Fe substrate resulted in cracks at the edges of the structure, caused by residual stresses and the formation of brittle Fe-W intermetallic phases at the interface. However, introducing a nickel alloy (IN625) as an interlayer significantly alleviated these stresses and suppressed intermetallic phase formation. The W7Ni3Fe alloy primarily consisted of α-W and γ-(Ni-Fe-W) phases, while the deposited IN625 interlayer contained γ-austenite and Laves phases, and the SS316L formed γ-Fe and δ-Fe phases. Chromium diffusion from the IN625 into the γ-(Ni-Fe-W) phase of the W7Ni3Fe alloy promoted a strong metallurgical bond at the W7Ni3Fe/IN625 interface. Uniaxial tensile tests demonstrated a tensile strength of 521 ± 4 MPa and an elongation of 22 ± 2%.

Investigation of the interface and physical properties of a Kovar alloy/Cu composite wire processed by multi-pass drawing

Abstract A Kovar alloy composite wire inlaid with copper core was developed through hot isostatic pressing sintering and subsequent multi-pass drawing. The interface between the Kovar alloy and copper was revealed, and the physical properties of the composite wire were investigated. The results show that the Kovar alloy and copper diffuse mutually during the forming process, producing a stable metallurgical bond. When the diameter of the wire is 2.8 mm, a diffusion layer of about 16.5 μm was found at the interface. The concentration of the diffused element had a gradient distribution from the interface to both sides. Combining the excellent properties of Kovar alloy and copper, the composite wire has comprehensive physical properties. The electrical and thermal conductivities are 9.38 × 106 S·m−1 and 72.2 W·m−1·K−1, respectively. The composite wire has a low coefficient of thermal expansion, and the average coefficient of thermal expansion is lower than 6.36 × 10−6 ℃−1 in the temperature range of 25–450°C.

Comparative Analysis of Compressive Strength of Steel Tubing Pipe Welding Results Using SMAW and MIG Welding with 140A Current

The welding process plays a crucial role in manufacturing and is inseparable from its advancement. Deutsche Industrie Norman (DIN) defines welding as creating a metallurgical bond at the joint of metal or alloy metals in their molten state. This process is essential for constructing strong, durable materials like plates, steel, and pipes. Bending tests, including face bend and root bend, are often conducted to evaluate the quality of welded joints. These tests assess welded materials’ toughness, strength, and resistance under specific loading conditions. This study employed two welding techniques: Gas Metal Arc Welding (GMAW) and Shielded Metal Arc Welding (SMAW). GMAW, called Metal Inert Gas (MIG) welding, uses argon or helium as protective gases and a continuously fed electrode wire. On the other hand, SMAW relies on flux-coated electrodes to create the weld seam, with molten metal from both the electrode and parent material filling the joint. The results revealed distinct advantages for each method. The highest bending test value for the root bend was achieved with MIG welding at 982,55 Kgf/mm², demonstrating its effectiveness in creating durable root joints. Conversely, SMAW exhibited superior performance in face bend tests, achieving a bending strength of 104111 Kgf/mm², making it ideal for surface-level joint applications. Both techniques displayed no visible cracks in their welds, ensuring compliance with industry standards and confirming their reliability for various manufacturing needs. These findings highlight the importance of selecting appropriate welding methods based on specific application requirements.

Effect of Hot-Dipped Tin Coating Treatment on Metallurgical Bonds Between AZ91D and Cu by Composite Casting

Mg-Cu bimetallic materials have been widely studied because of their low density, good electrical conductivity, and excellent hydrogen storage properties. However, the interface bonding strength of Mg/Cu is low. In this study, we examined the effect of hot-dip tin coating (HDTC) with copper (Cu) on the interfacial metallurgical bonds between AZ91D Magnesium (Mg) alloy and Cu composite casting. A transition layer composed of Mg2Cu and MgCu2 intermetallic compounds (IMCs) formed at the interface of the AZ91D/HDTC-Cu composite casting. However, the transition layer was about 1 μm at the AZ91D/Cu interface, mainly comprising Mg(Al, Cu)2 IMC. Both the AZ91D/Cu and AZ91D/HDTC-Cu interfaces exhibited many labyrinthine Mg(Al, Cu)2 IMCs and layer-like Mg2(Al, Cu) IMCs. Moreover, the interfacial shear strength of the AZ91D/Cu was changed from 12.6 MPa to 52.4 MPa due to the solid solution of Sn atom and the precipitation of Mg2Sn IMC at the interface after HDTC treatment. Meanwhile, the shear fracture surfaces are characterized by brittle fractures.

Optimized strategy for induction cladding of diamond/Ni-based wear-resistant coatings

Optimized strategy for induction cladding of diamond/Ni-based wear-resistant coatings

Microstructure and material properties of 3D-printed bimetallic steels

Microstructure and material properties of 3D-printed bimetallic steels

Microstructure and mechanical properties of stainless steel 316L-Inconel 625 bimetallic structure fabricated by laser wire direct energy deposition

Microstructure and mechanical properties of stainless steel 316L-Inconel 625 bimetallic structure fabricated by laser wire direct energy deposition

Machine learning-based prediction of single clad characteristics and non-destructive characterization of multi-layer deposited FeCoNiCrMo HEA on EN24 via laser cladding

Machine learning-based prediction of single clad characteristics and non-destructive characterization of multi-layer deposited FeCoNiCrMo HEA on EN24 via laser cladding

Ni mesh-reinforced ultrasonic-assisted Cu/Sn58Bi/Cu joint performance: Experiments and first-principles calculations

Ni mesh-reinforced ultrasonic-assisted Cu/Sn58Bi/Cu joint performance: Experiments and first-principles calculations

Joining of the functionally gradient friction material to the backing plate for wind turbines using sinter-brazing technique

Joining of the functionally gradient friction material to the backing plate for wind turbines using sinter-brazing technique

Experimental study under thermal shock environment to investigate effect of welding width on properties of ultrasonically welded joints of multiple copper cables

Based on the ultrasonic welding technology, this study uses three different welding widths to weld copper cables with different specifications. The influence of welding width on the mechanical properties and microstructure of each group of welded joints was systematically studied for the first time. The thermal shock test was carried out for each group of welded joints under optimum welding width to simulate the influence of severe temperature change environment on joint performance. It is found that the cross-sectional area of joint is 20 mm2 and optimal welding width of joint composed of two and three cables is 7 mm. The optimal welding temperature of the joint composed of four cables is 5 mm. Under the optimal welding width, the average shear strength of two-cable joint reaches 309.4 N. The four-cable joint is only 232.2 N. Moreover, the welding strength weakens significantly as the number of cables and the peak temperature decreases. The high temperature of bonding interface is the key factor to form a good weld. The peak temperature during welding is negatively correlated with the porosity of joint and positively correlated with peeling strength of joint. In addition, the morphology of ultrasonically welded joints has changed obviously after thermal shock test. With the participation of oxygen, the surface of welded joint is gray and bright brass, while the interior of joint is purple due to lack of oxygen. Moreover, the phenomenon of atomic diffusion and thermal expansion generates joints which were initially in a mechanically interlocked form and welding interface of the metallurgical bond under the action of high temperature. So the maximum joint peel strength is slightly improved.

Synthesis and Characterization of AA6351/SiC Composites Using Ball Milling Combined with Hot Extrusion

<div>In this investigation, AA6351 alloy matrix composites with a larger volume proportion of SiC (20 wt%) were fabricated and tested for microstructure and mechanical behavior. Composites were hot extruded from mechanically milled matrix and reinforcements. Hot extrusion uniformly distributed reinforcements in the matrix and strengthened phase interaction. Mechanical ball milling causes AA6351 powder to become more homogeneous, reducing the mean particle size from 38.66 ± 2.31 μm to 23.57 ± 2.31 μm due to particle deformation. The micrograph shows that the SiC particles are equally dispersed in the AA6351 matrix, avoiding densification and reinforcing phase integration issues during hot extrusion. In hot extrusion, SiC particles are evenly distributed in the matrix, free of pores, and have strong metallurgical bonds, resulting in a homogenous composite microstructure. SiC powders and mechanical milling increase microhardness and compressive strength, giving MMC-A 54.9% greater than AA6351 alloy (as unmilled). With 175.82% strength and ductility, MMC-B outperforms MMC-A. This shows that coarse-grain AA6351 improves the composite’s compressive strength and ductility. This study improves mechanical performance by employing mechanical milling and hot extrusion to get fine AA6351 matrix grain size and homogenous SiC reinforcement.</div>

Femtosecond laser joining of Stellite and stainless steel

Femtosecond laser joining of Stellite and stainless steel