Solid State Diffusion Bonding Process-A Review Aravinda, T; Niranjan, H B; Satish Babu, B ...
IOP conference series. Materials Science and Engineering,
01/2021, Letnik:
1013, Številka:
1
Journal Article
Recenzirano
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The present paper reports on the various diffusion bonding techniques using atomic diffusion of elements at the interface. The bonding process is used mainly for joining dissimilar metals. However, ...two similar metals can also be bonded with or without using an interlayer. Dissimilar materials include metalceramic; interlayer can also be used if necessary, in between the interfaces. The other methods of joining would probably interfere with the microstructure of the base metal at the point of interface. Various methods of joining like welding create reaction between the materials in the molten pool. Residual stresses would not appear at the bonding site, neither has it created thermal gradients using diffusion technique. Distortion observed in diffusion bonding is quite less compared to other joining process. It is also observed that the interface retains similar mechanical and physical properties as that of the base material. The strength at the interface depends on parameters like temperature, pressure and time taken for contact while forming the solid state bond.
The light weight and complementary properties of Mg and Ti give Mg/Ti composites great development potential. The design and exploitation of high-quality and low-cost fabrication technologies support ...the advancement of Mg/Ti composites. In this study, Mg/Ti composites were fabricated without interlayer by reaction-diffusion between Al and Ti in AZ91 and TA2 alloys, respectively. The formation order of the interfacial intermetallic was deduced by thermodynamics calculations. The feasibility of interlayer-free diffusion bonding Mg/Ti composites held for 1–3 h was scrutinized by observing the microstructural evolution of the Mg/Ti interface and testing the mechanical properties of the Mg/Ti composites. The results indicated that with increasing holding time, diffusion bonding became more compact and joint quality improved. A high-quality bond formed between the Mg and Ti held for 3 h. The interfacial intermetallic layer formed a continuous and compact Al3Ti + Ti3Al duplex structure. The contents of the Al3Mn nanophase and Mg17Al12 decreased gradually with increasing holding time. Owing to the highest volume of Mg attached to the Ti side and the formation of a few dimples, the tensile strength and elongation of the Mg/Ti composite were increased by 88.8 and 99.6%, respectively, by extending the holding time to 3 h.
•Al preferentially reacted with Ti below 427 °C, which provided concept for bonding insoluble and nonreactive Mg/Ti.•Interlayer-free Mg/Ti composites were fabricated by diffusion bonding successfully.•Interfacial intermetallic layer formed continuous, compact Al3Ti/Ti3Al duplex structure .•At 3 h, tensile strength and elongation increased by 88.8 and 99.6%, respectively.
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•Normalized bonding temperature links bonding temperature to material melting point.•Bonding pressure normalized by yield strength at bonding temperature.•Bonded ratio has a linear ...relation with pressure in plastic deformation mechanism.•Normalized bonding pressure for diffusion bonding can be adjusted from 0.05 to 0.577.
The model of the diffusion bonding pressure was established using the analysis calculation method and further verified by the finite element analysis (FEA) and the experiments. The normalized temperature was defined as the ratio of temperature and the melting point of the base materials. And the normalized bonding pressure was defined as the ratio of the applied bonding pressure and the yield strength at the bonding temperature. The contribution of the plastic deformation to the void closure expressed a linear relationship with the normalized bonding pressure, of which the slope was 3. The relationship was appropriate in TiAl6V4, pure copper C11000, aluminium alloy AA6061, stainless steel SUS 304, and Ni-based alloy Inconel 617 using analysis calculation. The diffusion bonding pressure design range can be summarized as σn = 0.05–0.577. Subsequently, the analytic computational model was verified by FEA. The results showed that the maximum stress was concentrated in the position of the void neck. And the linear relationship between the normalized bonding pressure and the bonded ratio was also tenable. There was a stable static error existed between FEA and the analytic computational analysis. Furthermore, the experimental verification showed the verification and accuracy of the analytic computational analysis results.
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•A high entropy interlayer (TiZrHfNb)95Al5 was successfully designed for diffusion bonding of GH4169 to Ti2AlNb.•The relationships between grain characteristics, lattice mismatch and ...mechanical properties, fracture mechanisms were revealed.•The major cracks located at the elastic modulus dramatically changed interface, i.e., the no-coherent interface.•The highest shear strength reached 384 MPa at 980 °C for 90 min.
A high entropy interlayer (TiZrHfNb)95Al5 was successfully designed for vacuum diffusion bonding of GH4169 superalloy to Ti2AlNb alloy. The relationships between grain size, grain boundary, lattice mismatch and microhardness, elastic modulus, shear strength and fracture behaviors were revealed. The typical microstructure was Ti2AlNb/B2/Solid solution/(Ti, Zr, Hf)2(Ni, Nb)+(Ti, Zr, Hf)(Ni, Nb) + Solid solution/(Ti, Zr, Hf)(Ni, Nb) + (Cr, Ni, Fe)ss/(Cr, Ni, Fe)ss/Cr-rich(Cr, Ni, Fe)ss/Ni-rich(Cr, Ni, Fe)ss/GH4169. With the holding time increased, the shear strength overall increased and decreased sharply, and the highest shear strength reached 384 MPa at 980 °C for 90 min. The microstructure had anisotropic crystal orientation, and the joints of Zone Ш for 90 min consisted of 92.08 % HAGBs and 7.92 % LAGBs. The residual strains and stresses decreased when the holding time increased. Meanwhile, recrystallisation appeared in Zone Ш, and the increase in the recrystallisation rate led to grain refinement. The lattice mismatch between (Ti, Zr, Hf)(Ni, Nb) and (Cr, Ni, Fe)ss phases was 25.05 %, indicating that the interface was non-coherent, and (Ti, Zr, Hf)(Ni, Nb)+(Cr, Ni, Fe)ss phases were located at an elastic modulus dramatically changed interface. Thus, the cracks easily formed in this interface and led to joint fracture. Moreover, the fracture mechanism was brittle fracture.
To avoid loss in mechanical property and reduce the production cost of the matrix titanium and Ti2AlNb-based alloys, lowering the temperature of the diffusion bonding is challenging research worth ...studying. In this work, surface mechanical nano-alloying treatment is applied to the TA2 titanium and Ti2AlNb-based alloy to deposit a coating of WC and W phases particles as a gain interlayer. Deposited and removal-deposit samples are respectively diffusion-bonded into the dissimilar alloy joints at a low temperature of 800 °C for 1 h under the pressure of 10 MPa. The microstructure, surface morphology, and element and phase compositions of the deposit on the surface and on the interface of the joints were investigated. The dynamic transformation of the deposited phase is discussed in detail. The phase transformations from WC to W and from WC or W to TiW occur during the deposit and diffusion bonding, respectively. The joint, boned with deposited samples, presents an 11.5% higher shear strength than the joint boned with removal-deposit samples. The detailed discussion suggests that the deposited phases and their corresponding phase transformation products present a nanograin characteristic during and after the diffusion bonding process that would promote the atoms' diffusion and strengthen the bonded joint. The present findings provide a new strategy for obtaining high-mechanical performance joint of diffusion bonding through a specific nano-alloying deposit coating.
•An approach for fabricating high-quality DB joints using nano-alloying coating by SMNAT was first proposed.•Tungsten carbide (tungsten) coatings were prepared on TA2 titanium and Ti2AlNb alloy by SMNAT.•Phase transformation occurs from the WC to the W, and from the WC to the TiW during the SMNAT and DB process respectively.•Nano TiW and WC grains in the deposit promote the atoms' diffusion on the interface.•Ultra-fined particles with nano TiW and WC grains strengthen the DB joints.
To efficiently explore the influence of Fe content on the phase stability of the multicomponent CoCrFexNiMn (hereafter abbreviated as Fex) alloys. A diffusion layer with continuous, concentration ...gradient of Fe element is created based on diffusion couple technique. The microstructure and element distribution of the diffusion bonded layer between Fe0.2 and Fe16 alloys are analyzed. A new layer of FCC and HCP solid solution phases generates in the diffusion zone, which is consistent with the prediction of parametric approach and phase diagram calculation. As diffusion proceeds, the FCC phase is transformed from the BCC phase with the decreasing of Fe content and the HCP phase might be the transitional phase during this transition. The newly formed FCC and HCP phases are shown specific orientation relationships with the BCC phase. Elemental analysis indicated that the diffusion rate of the alloy components in the FCC phase is Cr > Mn > Co > Ni. The large concentration gradient in the diffuse interface and grain boundaries diffusion of BCC phase promoted the Fe diffusion, causing the BCC phase to transform into FCC phase.
•The reliable joint of Fe0.2 and Fe16 alloys is achieved by diffusion bonding method.•Newly formed FCC and HCP phases obey the classical Burgers OR with BCC phase.•Compared with Fe16, the diffusion of Fe0.2 is insufficient during diffusion bonding.
To prepare large-sized and complex-shaped components, the feasibility of direct diffusion bonding of (Hf0.2Zr0.2Ti0.2Ta0.2Nb0.2)C high-entropy ceramic (HEC) and its diffusion bonding with a metallic ...Ni foil was investigated, and the interfacial microstructure and mechanical properties of HEC/HEC and HEC/Ni/HEC joints were analyzed. For the direct diffusion bonding, reliable joints with a shear strength of 146 MPa could be achieved when the bonding temperature reached 1500 °C under a pressure of 30 MPa. By introducing a metallic Ni foil as the interlayer, the HEC was successfully bonded at the diffusion temperatures from 1150 °C to 1250 °C under 10 MPa through the formation of Ti2Ni compound phase. Meanwhile, the HEC(Ni) phase formed by the diffusion of Ni into HEC and Ni(s, s) bulks precipitated in the bonding transition zone. The maximum joint shear strength of 151 MPa was obtained by optimizing the Ni-foil thickness, bonding temperature, and holding time.
•High-quality OFHC-Cu/ODS-Cu joints were obtained by HIP diffusion bonding.•Increasing joining temperature or adding Ni interlayer reduce interfacial voids.•The Cu-OFHC/ODS-Cu#900 joint exhibited an ...impact toughness of 133.1 J/cm2.•The Cu-OFHC/Ni/ODS-Cu#680 joint had an impact toughness of 122.5 J/cm2.•Creep deformation and sufficient atomic diffusion resulted in the closure of voids.
Compared to CuCrZr, oxide dispersion strengthened copper alloy (ODS-Cu) exhibits higher stability of properties under irradiation and exposure to elevated temperatures, demonstrating broad application prospects in divertor components. Oxygen-free high thermal conductivity copper (Cu-OFHC) has been frequently employed as an interlayer between W and Cu-based alloy in the fabrication of W/Cu divertor components. This study investigates the effect of joining temperature together with the addition of a Ni interlayer on the interface microstructure and mechanical properties of the Cu-OFHC/ODS-Cu joints. As the joining temperature increased from 680 ℃ to 900 ℃, the interface bonding ratio of the Cu-OFHC/ODS-Cu joints improved from 40.4% to 95.8%, and the impact toughness increased from 23.4 J/cm2 to 133.1 J/cm2. With the addition of a Ni interlayer, the interface bonding ratio increased from 40.4% to 90.3%, and the impact toughness improved from 23.4 J/cm2 to 122.5 J/cm2. Increasing the joining temperature or adding a Ni interlayer effectively reduced interfacial voids, enhanced the interface bonding ratio, and consequently improved the impact toughness of Cu-OFHC/ODS-Cu joints. Then, the W/Cu/ODS-Cu monoblock mock-ups with good interfacial bonding were successfully fabricated under two conditions: at a joining temperature of 900 ℃ without an interlayer and at 680 ℃ with a Ni interlayer. These results provide a fundamental understanding for achieving high-quality Cu-OFHC/ODS-Cu joints and offer technical support for the engineering preparation of W/Cu/ODS-Cu components in future fusion devices.
Brittle compounds and large residual stresses are easily formed at the diffusion bonding (DB) joints of dissimilar intermetallic compounds, which will deteriorate the performance of the joints. In ...this study, in order to conduct an in-depth study of the strengthening mechanisms, the post-bonded heat treatment (PBHT) and post-bonded hot deformation (PBHD) were applied to the TiAl/Ti2AlNb DB joint. Comparative studies were implemented aiming to reveal the strengthening mechanisms and their influence on interfacial microstructure and mechanical properties. The experimental results indicated that the harmful intermetallic compound AlNb2 phase in the DB joint was eliminated by PBHT and PBHD. Meanwhile, the diffusion layers were changed from O + (AlNb2+α2) + (α2+β/B2+γ) three layers of DB joints to (α2+β/B2+O + Ti3NbAl2) + (α2+β/B2+γ) two layers of PBHD joint. Interestingly, the Ti3NbAl2 phase was first found in the DB joint after PBHD. After testing, the tensile strength and the relative tensile strength (defined as the tensile strength ratio of the joint and the TiAl alloy) of samples increased by 272.54 MPa and 39.2% after PBHD, respectively. In comparison, the tensile strength and the relative tensile strength of samples increased by 75.96 MPa and 10.96% after PBHT. This demonstrated that PBHD could induce the formation and uniform dispersion of the Ti3NbAl2 phase, which is indispensable to improve the tensile strength of the TiAl/Ti2AlNb DB joint.
•PBHD was first introduced in the diffusion bonding of dissimilar TiAl-based alloy.•The Ti3NbAl2 phase was first found in TiAl/Ti2AlNb diffusion bonding joint.•The tensile strength and the relative tensile strength after PBHD increased by 272.54 MPa and 39.2%, respectively.
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