Powder Interlayer Research Articles

Microstructural evolution and properties of CuW/CuCr interface infiltrated with CuCrNixTiZr multi-component powder interlayers

CuW/CuCr integral materials were prepared by infiltration diffusion technology, and the multi-component powders with high entropy effect were used as the interlayer. The effects of CuCrNixTiZr high entropy alloy interlayers on the interfacial microstructures and properties of CuW/CuCr were studied. The results show that the interlayers with 0.5 mm thickness generate high entropy effect during infiltration for 1.5 h at 1350 °C, forms a simple solid solution phase at the CuW biphase interface and no intermetallic compounds were formed in the CuW/CuCr interface. EDS and XRD analysis show that metallurgical diffusion and melting occur at the CuW/CuCr interface in the interlayer infiltration diffusion process, which makes the Cu and W phase form metallurgical bonding at the Cu/W interface. With the increase of Ni content, the hardness of CuCr side of the integral material first increased and decreased, and the maximum hardness increases by 23.6 %. When the interlayer is CuCrNi2TiZr, the maximum interface bonding strength is 492 MPa, which is 50 % higher than that of the integral material without interlayer. The fracture morphology is mainly composed of the network structure generated by the ductile tearing of Cu phase and W cleavage fracture, and the cleavage fracture leave river pattern on the W particles.

CFD investigation on thermal hydraulics of the double-wall bayonet tube heat exchanger in CLEAR-S facility

The double-wall bayonet tube type heat exchanger design can monitor and mitigate the occurrence of Steam Generator Tube Rupture (SGTR) accidents, which is one of the most important accidents of GEN-Ⅳ lead-cooled Fast Reactor (LFR). The lead-based reactor engineering validation facility CLEAR-S will be used for the integrated testing and verification of the megawatt-level double-wall bayonet tube heat exchanger. In this study, the Shear Stress Transport turbulence model (SSTk-ω) was used to pre-simulate the thermal characteristics of the CLEAR-S double-wall bayonet tube heat exchanger before the experiment. The verification shows that the numerical simulation results of the single bayonet tube structure are in good agreement with the RELAP5 simulation results and experimental data from CLEAR-S. CFD analysis reveals that the non-effective heat exchange area will preheat the liquid water on the side of the tube, so that the overall heat exchange performance decreases by about 4%. The heat conduction of the powder interlayer is the largest heat transfer resistance, which weakened the influence of the lead-bismuth eutectic (LBE) side flow and temperature inhomogeneity on the heat transfer of the tube bundle and significantly reduced the wall radial temperature difference of each bayonet tube. The conclusions of this study can provide a reference for the experiment and design of double-wall bayonet tube heat exchangers.

Effect of powder size in microwave joining of oxygen-free copper to SS304

This paper investigates the prospect of microwave hybrid heating to join oxygen-free copper with stainless steel (SS304). The effect of size of copper (Cu) powder interlayer in the microstructure and mechanical properties of the joint formed is investigated, along with the incites on the mechanism of joint formation. Cu powder of average sizes 4 and 45 μm was studied. The microwave heating rate was observed to be high for 4 μm Cu in the absence of voids or porosities in the joint region. Voids were observed in the interlayer when 45 μm Cu powder was used. The joint was formed due to volumetric diffusion of the major elements of the substrates, e.g. Fe, Cu, Cr that was verified by energy dispersive spectroscopy. Oxides were present for 45 μm Cu which was absent for 4 μm Cu. X-ray diffraction and energy-dispersive X-ray spectroscopy analysis concluded that no intermetallic compound was formed along the interlayer. The micro-hardness of ∼128 HV was observed to be uniform across the interlayer depicting a good metallurgical joint. The maximum tensile shear strength of 83.12 MPa was recorded for 4 μm copper powder and microwave time of 14 min, exhibiting ductile failure of the joint.

Microstructure and Properties of Cuw/Cucr Joint with Cucrnixtizr Multi-Component Powder Interlayer by Infiltration Technology

Microstructure and Properties of Cuw/Cucr Joint with Cucrnixtizr Multi-Component Powder Interlayer by Infiltration Technology

Powder Interlayer Bonding of Nickel-Based Superalloys with Dissimilar Chemistries

Novel joining methods are crucial for the aerospace industry to repair components damaged in the high stress, high cycle environment of the jet turbine engine. Powder interlayer bonding (PIB) is a novel joining technique that is being explored for use in the aerospace industry. PIB involves the use of a powder interlayer between two faying surfaces alongside a localised temperature gradient and compressive force to produce one joined workpiece. The use of a localised temperature gradient not only reduces the heat affected zone (HAZ) but also reduces the energy requirements for the process as only a small area of the component needs to be elevated in temperature. Nickel-based superalloys are commonly used in the gas turbine engine due to their superior mechanical properties that are maintained even under the most elevated temperatures experienced in the jet turbine engine. It is therefore essential these alloys can be easily repaired. Conventional joining methods such as friction welding have proved difficult for new generation nickel-based superalloys; therefore, there is much interest in PIB as an alternative repair technology. This study shows the potential of PIB to join dissimilar nickel-based superalloys: bonds with very little porosity were observed after only a short processing time.

Transient liquid phase bonding of Cu and Al using metallic particles interlayers

The bonding strength, and microstructures of Cu and Al couples using metallic powders as interlayer during transient liquid phase bonding (TLP bonding) were investigated. The interfacial morphologies and microstructures were studied by scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, and X-ray diffraction. First, to explore the optimum bonding time and temperature, nine samples were bonded without interlayers in a vacuum condition. Mechanical test results indicated that bonding at 560°C in 20 min returns the highest bond strength (84% of Al). This bonding condition was used to join ten samples with powder interlayers. Powders were prepared by mixing different combinations of Cu, Al (+Fe nanoparticles) and Zn. In the bonding zone, different Cu9Al4, CuAl, and CuAl2 intermetallic co-precipitate. The strongest bonding is formed in the sample with the 70Al (+Fe)-30Cu powder interlayer. Powder interlayers present thinner and more uniform intermetallic layers at the joint interface.

Microstructure and Interfacial Reactions of Resistance Brazed Lap Joints between TC4 Titanium Alloy and 304 Stainless Steel Using Metal Powder Interlayers.

In the brazing joint between titanium alloy and stainless steel, a lot of Fe-Ti intermetallic compounds (IMCs) can be easily formed to make joints crack. A lap resistance brazing process with metal powder layers on both sides of the filler metal was used to solve this problem. The microstructure and metallurgical behavior of joints was studied through comparative experiments. The result showed that Nb, V and Cr powders and the solder reacted with the base material to form a new phase, which replaced the Ti-Fe brittle phase in the joint. At the same time, metal powder clusters hindered the diffusion of Ti and Fe elements and improved the distribution of new phases. The established atomic reaction model revealed the metallurgical behavior and formation mechanism of the joints. Therefore, the intervening position of the metal powder layer and the multi-reaction zone structure are the main reasons the shear strength of joints is improved.

Dissimilar Metal Joining of Ti and Ni Using Ti-Al Powder Interlayer Via Rapid Thermal Explosion Method

To achieve the low energy consumption and high strength joining between Ti and Ni, a novel joining method (rapid thermal explosion, TE) was developed for joining dissimilar metals using Ti-Al mixture powders as flux. The TE reaction temperature of Ti-Al flux was measured, and the microstructure and mechanical properties of Ti/Ni joint were investigated. The results reveal that the combustion temperature of the Ti-Al powder interlayer is 1103 °C, which is higher than the joining temperature, and an obvious self-exothermic phenomenon lasts 20 s. The intermetallic compound diffusion layers formed at both interfaces mainly owing to the diffusion of Al and the growth activation energy of diffusion layers near both interfaces are 79.68 kJ/mol and 38.26 kJ/mol, respectively. Based on the sheer strength and diffusion layer, the formation mechanism of Ti/Ni joints is metallurgical bonding through atomic diffusion and formation of the diffusion layer.

Effect of Powder Interlayer on Copper Alloy Lap Joint by Laser Welding

In this paper, the lap joint of H62 copper alloy was carried out by pulsed laser welding. The effects of different powder interlayers on the microstructure, shear properties and corrosion properties of H62 copper alloy lap joints were studied. The results show that the welding joints with proper powder interlayer have achieved good welding forming. There are no defects such as pore and crack in the welding joints. The welding joints are fully penetrated with different powder interlayers except Ni powder interlayer. The grain size of weld is smaller than that of base metal. The maximum polar density of base metal is 6.46 in (001) [0–10] cubic texture, and there are two weaker (112) [111] Cu textures and (111) [1–21] textures. The maximum polar density of the weld is 5.39. The maximum position deflects, and (001) [0–10] cubic texture disappears. The weld is confused compared with the base metal, and the grain distribution is basically of random orientation. The addition of Zn powder reduces the welding stress. The shear strength of welding joints with Zn powder interlayer is the best, 82.27 MPa, which is 18% higher than that of welding joints without powder. The corrosion resistance of welding joints with different powder interlayers is as follows: no addition > Ni Powder > Zn Powder > Sn powder.

The joining of gamma titanium aluminides via the powder interlayer bonding method

Powder interlayer bonding (PIB) is a joining technique originally developed to enable high-integrity repairs of aerospace components. The technique has previously been employed for the joining of titanium and nickel alloys utilised in the aerospace industry. This study expands on the application of the novel joining technique known as powder interlayer bonding (PIB), to the bonding of γ titanium aluminide (TiAl) material. PIB has been used to facilitate high-integrity joints in gamma titanium aluminides (TiAl), where full densification of the joint was achieved. The PIB technique described here used a metallic powder interlayer between the two faying surfaces of γ TiAl specimens. Bonds were formed in an inert atmosphere under induction heating. The PIB technique proved capable of producing high-integrity bonds in terms of microstructural evaluation, with very limited porosity retained after the bonding cycle. A brittle Ti2Al phase can be produced with heavily oxidised powder which is susceptible to cracking and will negatively affect mechanical properties.

The fatigue performance of titanium alloys joined via the powder interlayer bonding method

This study investigated the fatigue performance of two forged variations of α + β titanium alloys, namely Ti-6Al-4V (Ti-6-4) and Ti-6Al-2Sn-4Zr-6Mo (Ti-6-2-4-6) joined via the powder interlayer bonding (PIB) process. Both alloys were bonded at relevant temperatures in the specific alloy’s α + β region. Modifications to the microstructure during the bonding process where it recrystalised into a bi-modal structure, resulted in improved low cycle fatigue (LCF) response for the Ti-6-4 alloy. This improvement is seen throughout the fatigue curve when compared to the LCF performance of the as received Ti-6-4 material. The improvement in LCF performance resulting from the microstructure transformation overcomes any reduction in performance that can be attributed to retained porosity after the bonding cycle. While the HCF performance of the Ti-6-2-4-6 alloy joined via the PIB process fell below that of the as received β-forged billet material, the fatigue performance compares well with previous HCF results for welded material. Unlike the Ti-6-4 alloy, the β-forged Ti-6-2-4-6 alloy does not benefit from the transformation of its microstructure throughout the bond region.

The Effect of Processing Variables on Powder Interlayer Bonding in Nickel-Based Superalloys.

Powder Interlayer Bonding (PIB) has been considered as a lower-energy joining technology for nickel-based superalloys compared to conventional methods; such as friction welding. Typically; nickel-based superalloys exhibit high energy requirements for joining due to their high operating temperatures. However; PIB utilizes a localized temperature gradient created by an induction current; reducing the energy requirements for the process. PIB is a solid-state joining method that compresses and heats a powder interlayer between two faying surfaces to produce one joined workpiece. It has been successfully used to bond titanium alloys; and the objectives of this work were to explore its application as a joining method for nickel-based superalloys. Initial results showed that joining nickel-based superalloys via PIB is possible; and bondlines with very little porosity were observed. Further analysis showed that these bonded areas had lower porosity than the base material; suggesting PIB could be a successful joining method for difficult-to-join nickel-based superalloys.

The Bonding of Additive Manufactured Ti-6Al-4V via the Powder Interlayer Bonding (PIB) Process

Powder interlayer bonding (PIB) is a novel joining technique. The technique has been developed to facilitate high integrity repairs of aerospace components, manufactured from titanium alloys commonly employed in the aerospace industry. The PIB technique utilises an interlayer between the two faying surfaces. In this study heating was supplied via induction, enabling a bond to be created in an inert atmosphere, shielding the fusion zone from oxidation during bonding. The PIB technique proved capable of producing high integrity bonds in additive manufactured Ti-6Al-4V, where approximately 85% of the strength of the alloy is retained after bonding. Advantages of this technique over more established joining methods such as tungsten inert gas (TIG) welding and plasma arc (PA) welding include a narrow fusion zone and localised heating. It is believed that PIB can compete against these more mature techniques, providing a technique suitable for joining a range of alloys found in the aerospace industry.

The Bonding of Additive Manufactured Ti-6Al-4V via the Powder Interlayer Bonding (PIB) Process

Powder interlayer bonding (PIB) is a novel joining technique. The technique has been developed to facilitate high integrity repairs of aerospace components, manufactured from titanium alloys commonly employed in the aerospace industry. The PIB technique utilises an interlayer between the two faying surfaces. In this study heating was supplied via induction, enabling a bond to be created in an inert atmosphere, shielding the fusion zone from oxidation during bonding. The PIB technique proved capable of producing high integrity bonds in additive manufactured Ti-6Al-4V, where approximately 85% of the strength of the alloy is retained after bonding. Advantages of this technique over more established joining methods such as tungsten inert gas (TIG) welding and plasma arc (PA) welding include a narrow fusion zone and localised heating. It is believed that PIB can compete against these more mature techniques, providing a technique suitable for joining a range of alloys found in the aerospace industry.

Powder interlayer bonding of geometrically complex Ti-6Al-4V parts

Powder interlayer bonding (PIB) is a novel joining technique, which has been developed to facilitate high-integrity repairs of aerospace components, manufactured from commonly used titanium alloys. The PIB technique utilises an interlayer between complex geometric components which are mated under pressure and a highly localised heating source. In this study, induction heating enabled bonding in an inert fusion zone by use of an oxygen-displacing shielding gas, with particular attention to the initial heating and pressure application. These early stages proved crucial to the elimination of pores and consolidation of the alloy powder, with porosity volume fraction reduced to just 0.5% after just 20 sec at the bonding force. The technique has produced high-integrity bonds in alloys such as Ti-6Al-4V, retaining approximately 90% of the alloy strength in previous studies, offering advantages over established joining methods such as tungsten inert gas (TIG) and plasma arc (PA) welding due to a more highly localised heating and fusion zone. It is believed that powder interlayer bonding can compete against these techniques, providing a more time and cost-effective repair route for net shape components manufactured from a range of alloys with minimal post-processing.

Pressureless thermal diffusion bonding of transparent AlON ceramics by using a powder interlayer of parent material

Two transparent AlON ceramics substrates were successfully pressureless joined at 1880 °C for 80 min by using a powder interlayer of parent material. The grains on the interface of the joint were simultaneously shared by both interlayer and substrates due to grain growth and coalescence, which can evidently be categorized as thermal diffusion bonding under pressureless condition. The identical phase assemblage and microstructure for both interlayer and substrates lead to a bending strength of the joint (229.1 MPa) nearly equal to that of substrates, which is much higher than that of the reported AlON joints.

On the Role of Bonding Time on Microstructure and Mechanical Properties of TLP Bonded Al/Mg2Si Composite

Transient liquid phase diffusion bonding of an aluminum metal matrix composite with 15 wt.% Mg2Si reinforcement particles using Cu powder interlayer at 560 °C for different bonding times has been studied. Three different zones were identified at the bonding line: athermally solidified zone, isothermally solidified zone and base metal. By increasing the bonding time, due to the diffusion of copper to the substrate, the width of the athermally solidified zone decreased, became more homogenous and the amount of intermetallic phase (CuAl2) decreased. Therefore, the shear strength increased to a maximum of 60 MPa for the samples with a holding time of 5 h at the bonding temperature.

Powder interlayer bonding of titanium alloys: Ti-6Al-2Sn-4Zr-6Mo and Ti-6Al-4V

This study introduces powder interlayer bonding (PIB) as a novel joining technique, for the high integrity repair of components, fashioned from two titanium alloys commonly employed in the aerospace industry. The PIB technique in this study utilised a metallic powder interlayer between the two faying surfaces. Heating was provided via induction to create a bond in an inert atmosphere. The PIB technique proved capable of producing high integrity bonds in both Ti-6Al-4V and Ti-6Al-2Sn-4Zr-6Mo. A reduction of less than 10% in strength is seen for bonds created with both alloys. The deficit seen in ductility for the alloys was deemed acceptable for the industrial applications considered.

Using reaction heat of laser-induced Al[sbnd]Ti[sbnd]C interlayer to connect CFRTP/aluminum

The carbon fiber reinforced thermoplastics (CFRTP) was successfully joined to aluminum using a laser-induced AlTiC powder interlayer. The selection principle of the composition and content of the interlayer was studied. We calculate the composition and content of the interlayer material is Al54Ti32C14. The influence of connection temperature and connection pressure on the mechanical properties of the joint is studied. The results show that the connection temperature is 1600 °C and the connection pressure is 30 N, the maximum shear strength of the joint can reach 5.2 MPa. This experiment uses exothermal reaction of AlTiC powder by laser induces self-propagating reaction to connect aluminum and CFRTP. In the aluminum side, the metallurgical reaction between interlayer and aluminum produces Al3Ti. In the CFRTP side, under the action of pressure, using the heat generated by the self-propagating reaction to melt the CFRTP, the molten CFRTP into the micro-hole of interlayer to form mechanical interlock. At the same time, element diffusion occurs at the interface, thus forming mechanical interlocking and diffusion connections.

Pressureless joining of SiC ceramics at low temperature

Pressureless joining of SiC ceramics at low temperature was developed using Ti powder interlayer. Phase assemblage and microstructure of SiC joint revealed that the products after diffusion bonding mainly consisted of Ti5Si3 and TiC owing to the comparatively low joining temperature. Additionally, Si and C elements were found to be with higher penetration depth in the Ti interlayer. Benefitting from the lower proportion of the brittle Ti5Si3 phase and porosity, shear strength reached a relatively higher value of 41 MPa after joining at 1200 °C for 30 min.