TC4 Side Research Articles

Microdeformation and strengthening mechanism of 3D printed TC4/TC11 gradient titanium alloy subjected to tensile loading

3D printing of heterogeneous alloys holds promising application potentials in industry, especially in the field of aerospace. However, the relationship between the microstructure and mechanical properties of heterogeneous gradient titanium alloys produced by this technique, especially the micromechanical properties and mechanisms within the gradient zones, remains largely unexplored. In this study, we investigated the tensile micromechanical properties and deformation mechanism of 3D printed TC4/TC11 titanium alloy using the digital image correlation method in combination with scanning electron microscopy. The results show that this heterogeneous gradient titanium alloy possesses superior tensile properties. Furthermore, we elucidated the influence of microstructure and grain size on the alloy’s mechanical properties. Notably, an increased presence of secondary α phases and refined grain size were found to reduce the likelihood of microcrack initiation and propagation. Interestingly, all samples fractured on the TC4 side, with the microcracks predominantly extending at a 45° angle to the tensile direction. This observation underscores the necessity for optimizing the fabrication process of the TC4 alloy. Additionally, the strengthening mechanism of the gradient-bonded region of the alloy was also explored. The heterogeneous deformation-induced strengthening was identified as a key factor enhancing the strength of the dual alloyed zone. Collectively, this study provides valuable insights for optimizing the 3D printing process of heterogeneous gradient titanium alloys. It also lays a solid foundation for future investigation in this burgeoning field.

Research on the microstructure and mechanical properties of functional gradient materials of TC4/TC11 titanium alloys for wire arc additive manufacturing with different transitional forms

Functional gradient materials (FGMs) have garnered increasing interest for their potential in material and structural design. Additive manufacturing, as a kind of free manufacturing and near-net shaping technology with in-situ controllability of materials, is the dominant technology for fabricating FGMs. While numerous studies have been conducted on titanium alloy FGMs, there is still a lack of research on the structure and properties of the material with the number of transitional layers. This study employs double-wire arc additive manufacturing to fabricate FGMs composed of TC4 and TC11 alloys. The study examines the utilization of direct and continuous transition forms in conjunction with stress relieving and solution aging heat treatment processes. The composition, grain morphology, microstructure, and mechanical properties of FGMs are analyzed. Results indicate that in samples employing direct transition, higher heat treatment temperatures and durations lead to a more uniform composition and microstructure. Additionally, the interface morphology becomes increasingly indistinct, and transversal elongation at the interface is enhanced by the strain compensation of the two materials. In continuous transitional samples, an increase in the number of transitional layers results in a more uniform microstructure near the interface, leading to a reduction in interface morphology and an enhancement of mechanical properties. The fracture position tends to shift closer to the TC4 side, with both process forms exhibiting ductile fractures. The plasticity of the TC4 part is superior, and the ductile fracture morphology is more pronounced. This study offers a valuable experimental foundation for investigating the direct and continuous transition of titanium alloy FGMs.

The influence of Cu on the microstructure and properties of TC4/Q345 high-entropy joints by laser welding

FeCoNiCrCu high-entropy alloy (HEA) and Cu foils were utilized as the intermediate layer to conduct laser welding of TC4 titanium alloy and Q345 steel. Welding is performed by adding single HEA and Cu/HEA double foils as interlayer respectively. We conducted in-depth studies on the microstructure and mechanical properties of the joint by stereomicroscopy, metallographic microscope, scanning electron microscope (SEM), micro-area X-ray diffraction (XRD), nanoindentation, electron backscatter diffraction (EBSD), and tensile testing. The results indicate that the position of the copper foil significantly affects the microstructure and performance of the joint. When the copper foil is on the TC4 side, its lower melting point causes a deeper keyhole, resulting in a narrower weld bead and then reduced content of Fe and Ti in the weld. Simultaneously, the increased proportion of Cu in the weld significantly enhances the content of Cu-rich phases. In the weld zone, we observed freely distributed Cu-rich phases and Ti-rich phases generated along the interface. Under tensile loads, cracks primarily initiate and propagate along the Cu-rich phases, leading to typical delamination on the fracture surface. With the copper foil on the TC4 side, due to the increased copper content in the microstructure, the hardness of the interface between the titanium alloy and the weld decreases, while the joint exhibits the highest tensile strength, reaching a maximum of 417 MPa.

Intermetallic phase evolution and strengthening mechanisms of the titanium and stainless steel lap joints welded by interrupted pulsed arc welding

The study is focused on analyzing the intermetallic phase evolution and strengthening mechanisms of the titanium alloy and stainless steel (Ti-SS) seam-welded joints using interrupted pulsed arc welding (IPAW). The precise adjustment of welding parameters for the IPAW technique allowed for the successful creation of two different joining modes for Ti-SS joints: contact reactive brazing and fusion modes. The homogeneous composition in the brazing joints was achieved by the formation of a diffusion-driven eutectic liquid phase at the joining contact, resulting in an unusual eutectic structure consisting of β-Ti and TiFe. The molten pool at high temperatures caused an uneven distribution of composition and energy throughout the fusion joints. The fusion joints consisted of a Ti-rich layer, containing β-Ti and TiFe phases near the TC4 side, and a Fe-rich layer, containing TiFe2/TiCr2 and α-Fe phases near the 304SS side. The shear-bearing capacity of the joints exhibited an initial increase and subsequent decrease as the heat input increased. The low heat input resulted in the formation of the unwelding zone, which significantly reduced the shear resistance of the joints. With the increase of the heat input, a reduction in shear strength occurred due to the accumulation of TiFe2 brittle phases associated with the shift of the joining mode from the brazing to the fusion. The shear force decreased after reaching its maximum value, despite the joints being fully joined and the joining area expanding.

Laser melting deposition of Inconel625 to Ti6Al4V bimetallic structure via vanadium interlayer

Inconel 625 (IN625) nickel-based high-temperature alloy and Ti6Al4V (TC4) titanium alloy are widely used in the aerospace industry due to their respective excellent properties. Developing the IN625/TC4 bimetallic structure (BS) has more apparent benefits and broader application prospects. Still, it has been challenging for industry research to connect these two materials successfully. In this study, IN625/TC4 BS without metallurgical defects such as cracks was successfully fabricated by adding the V interlayer using laser melting deposition (LMD) technique, and its microstructure and mechanical properties were investigated. The results indicate that IN625/TC4 BS can be divided into five regions from the IN625 side to the TC4 side, namely IN625 region, IN625/V transition region, rich V region, V/TC4 transition region, and TC4 region. The phase evolution of the five regions is as follows: γ-Ni + laves → γ-Ni + (Ni2Cr)V + TiNi3 + (V, Cr, Ni) solid solution → (V, Cr, Mo) solid solution + TiNi → β-Ti + TiNi + Ti2Ni → α-Ti + β-Ti. The Vickers hardness in the transition region is not uniformly distributed, with the highest value reaching 955 HV. The tensile strength of IN625/TC4 BS via V interlayer is approximately 267.6 MPa. The fracture location is located at the interface between rich V region and V/TC4 transition region, and its fracture morphology displays features of a quasi-cleavage fracture.

Interfacial microstructure evolution and mechanical properties in laser welded Invar alloy/TC4 dissimilar joints

The present study examined the evolution of interfacial microstructure and its effect on the mechanical properties of Invar/TC4 dissimilar joints by laser welding. The results indicated that various intermetallic compounds (IMCs) were formed in the interface layer of the TC4 side, such as Ti2Cu, TiCu and TiNi phases, while the columnar dendrites grown epitaxially perpendicular to the fusion line were observed on the weld seam (WS). Moreover, the boundary between dendrites growing in different directions within the WS was attribute to the high thermal conductivity of the filler metal and the non-equilibrium rapid cooling facilitated by the composition gradient. Besides, excessive heat input intensified the migration of elements and phase transition behavior, leading to the formation of brittle Ti-Fe phases in the interface layer, which significantly weakened the mechanical properties of the dissimilar joints and resulted in brittle fracture characteristics. The strength of the joint exhibits a parabolic distribution with heat input. When the heat input was below 600 J/cm, the joint fractured in the interface layer of the TC4 side, with a maximum tensile strength of 298.4 MPa at 600 J/cm. However, when the heat input exceeded 600 J/cm, the formation of brittle Ti-Fe IMCs contributed to a decrease in joint strength. The investigation provides an efficient and stable method for achieving high-strength Invar/TC4 dissimilar alloy welding.

Ti386/TC4 clad plate manufactured by hot rolling and solution-aging treatment

Clad plate of high strength Ti386 and high plasticity TC4 is manufactured by hot rolling and solution-aging treatment. The interfacial microstructure and tensile properties of Ti386/TC4 clad plate are analyzed under different conditions. Results indicate that the clad plate subjected to 40% rolling reduction achieves a metallurgical bonding as there are no voids at Ti386/TC4 interface and the interfacial bonding strength is superior to the ultimate tensile strength (UTS) of Ti386 base (883 MPa). The microstructure of the clad plate is further refined as the rolling reduction increases to 80%, and the UTS of Ti386 increases to 921 MPa, which is still inferior to that the interface and TC4 base. After solution-aging treatment, the UTS of Ti386 is greatly improved to 1547 MPa, and the clad plate fractures at TC4 side with the UTS of 1010 MPa and elongation (δ) of 14.68%. Finally, the clad plate consisting of Ti386 with 1547 MPa UTS and TC4 with 14.68% δ is obtained with metallurgical interface.

Interfacial microstructure and mechanical properties of TiAl alloy/TC4 titanium alloy joints diffusion bonded with CoCuFeNiTiV0.6 high entropy alloy interlayer

In this paper, a novel CoCuFeNiTiV0.6 high entropy alloy interlayer was used for vacuum diffusion bonding of TiAl alloy and TC4 titanium alloy. The effects of bonding temperature and pressure on the interfacial microstructure, element diffusion behavior and mechanical properties of the joint were investigated. According to the microscopic morphological characteristics of the joint, it is divided into four zones. Zone I and zone III are the TiAl side interface diffusion layer and the TC4 interface diffusion layer, respectively. Zone II is the bonded high-entropy interlayer, and zone IV is the diffusion region of the TC4 substrate. Three diffusion layers of B2 phase, Al(Cu, Ni)Ti and Al(Co, Ni)2Ti phase were formed in zone I, while two diffusion layers of Ti-rich IMC and Ti2Ni phase were formed in zone III. With the increase of bonding temperature and pressure, the different diffusion layers on the TiAl side interface gradually thickened, and the β-Ti region on the TC4 side became wider and the Widmanstätten microstructure increased. The mechanical properties of the joints were evaluated by nanoindentation and shear tests. The hardness and elastic modulus at the TiAl side interface are up to 8.12 GPa and 158 Gpa, respectively, which is easy to cause stress concentration. The maximum shear strength reached 96.2 MPa bonded for 60 min at 960 ℃ under 1.7 MPa. The fracture location in the joint generally occurs at the interface of the Al(Cu, Ni)Ti layer/Al(Co, Ni)2Ti layer/HEA interlayer, and the fracture is mainly characterized by brittleness.

Thermal-strain-induced dynamic recrystallization and elements partitioning at heterogeneous bonding interfaces of titanium alloys

• Fine recrystallization grains are formed at the heterogeneous bonding interface. • The original bonding interfaces transform into different curved grain boundaries. • Elements partitioning occurs across the bonding interface with Mo and Nb diffusion. • No harmful heterogeneous precipitates formed around the bonding interface. The laminated bonding interfaces of Ti6Al3Nb2Zr1Mo (Ti-6321) and Ti6Al4V (TC4) form an interfacial transition zone during plastic deformation bonding. The interfacial dynamic recrystallization by lattice and subgrain rotation occurs around the bonding interface, inducing the formation of fine grains at the interface. The original bonding interface transforms into curved low or high-angle grain boundaries, suggesting that the bonding interface of dissimilar titanium alloys achieves complete metallurgical bonding. Moreover, elements partitioning occurs across the bonding interface with Mo and Nb in the α phase of Ti-6321 diffusing into the β phase of the TC4 side adjacent to the bonding interface.

Microstructure investigation and fracture mechanism of TC4−304L dissimilar joints fabricated by the cold metal transfer arc-brazing method

Wire feeding speeds of 3.5, 4.5, and 5.5 m/min are operated to arc-braze TC4 titanium alloy to 304 L stainless steel with the cold metal transfer method and CuNi filler wire. The microstructure and fracture behavior of TC4−304Ldissimilar joints were characterized by transition electron microscopy (TEM), selected area electron diffraction (SAED) patterns and X-ray microscope (XRM). The results show that the TC4/seam transition zone consists of an inner Ti-rich layer and an outer Ti-poor layer based on the line scanning result, which contains complex eutectic microstructures such as (Cu, Ni)Ti3, CuNiTi2, CuNiTi, (CuxNi1-x)Ti, and (Cu) solid solutions. The microstructure of the 304 L/seam interface consists of CuNi2Ti, (Cu, Ni) and (Fe, Ni) solid solutions. With increasing heat input, the thickness of the TC4/seam transition zone and the size of (Fe, Ni) dendrite grains increase, the ultimate tensile strength decreases from 350.8 to 230.5 MPa, and all samples fracture near TC4 side based on tensile samples and XRM results. The crack propagation is due to both the thickness of TC4/seam transition zone and a large amount of brittle CuNiTi equiaxial dendrite grains with a high hardness of 10.4 GPa.

Vacuum diffusion bonding of Ti2AlNb alloy and TC4 alloy

The Ti2AlNb alloy was joined with TC4 alloy by vacuum diffusion bonding. The relationship between bonding parameters, and joint microstructure and shear strength was investigated. The results indicated that the diffusion of Al, Ti, Nb and V elements across bonding interface led to the formation of three reaction layers: B2/β layer and α2 layer on the TC4 side, and α2+B2/β layer on the Ti2AlNb side. The bonding temperature determined the atomic activity, thus controlling the growth of reaction layers and influencing the shear strength of the joint. When the Ti2AlNb alloy and TC4 alloy were bonded at 950 °C for 30 min under 10 MPa, the shear strength of the joint reached the maximum of 467 MPa. The analysis on the fracture morphology showed that the fracture occurred within the B2/β layer and the fracture model was ductile rupture. Meanwhile, the formation mechanism of the Ti2AlNb/TC4 joint was discussed in depth.

Microstructural evolution and mechanical property of TC4/304 stainless steel joined by CMT using a CuSi3 filler wire

Abstract To obtain excellent spreadability under lower heat input and optimize interfacial microstructure, the spreading limited factors were analysed in wetting of liquid CuSi3 on 304ss and TC4 plates. At the CuSi3/TC4 joining side, the spreading model changed from diffusion-limited to reaction-limited with the interfacial temperature decreases which caused by the decrease of heat input. In the reaction-limited spreading, a continuously thin reaction layer (∼61 μm) was observed, consisting of Cu + Ti2Cu3 + TiCu4 + Ti5Si3, and TiCu + Ti2Cu + Ti5Si3. In the diffusion-limited spreading, a thin reaction layer was transformed to a thick (∼125 μm) one with intricate phases, containing primarily of Ti5Si3 + TiFe2+Ti2Cu3 + TiCu4, Ti5Si3 + TiCu + AlCu2Ti, and TiCu + Ti2Cu therein. The spreading energy provided by the interfacial reaction (26 kJ/mol) was higher than that provided by the diffusion of Ti atoms in copper (21 kJ/mol), i.e. the spreading rate under 65 A welding current with a 0.783 KJ/cm heat input was greater than that under 70 A with a 0.853 KJ/cm heat input. The rapid spreading with a short residence time at a high temperature could reduce the thickness of the interface layer. At the CuSi3/304ss joining side, CuSi3 droplet could not wet 304ss when the heat input was lower than 0.783 KJ/cm. The wettability was gradually improved with increasing heat input, and the spreading driving force was provided by the diffusion of Fe in liquid Cu. A typical solid solution interface without crack defects presented at the CuSi3/304ss. Under the dual effects of reaction-promoted spreading at TC4 side and diffusion-promoted spreading at 304ss side, a wrap-around joint with high strength (∼407.6 MPa) was formed.

Vacuum brazing ZSCf composite ceramics to TC4 alloy with Ag-Cu filler

In this study, the carbon fiber reinforced ZrB2-SiC composite ceramic was joined to Ti6Al4V alloy with Ag-Cu eutectic alloy filler at varied holding time and a fixed temperature of 800℃. Interface microstructure and shear strength of brazing joints were studied. The brazed ZSCf ceramics/AgCu/TC4 alloy is endowed with good metallurgical bondings. A typical interfacial structure of joints brazed for 10min was found as ZSCf/TiC/Ti5Si3/Ag(s,s)/Cu(s,s)+TiC/TiCu/Ti2Cu/(TiC+TiCu)/TC4 alloy. Increase of holding time did not vary the precipitated phase of the joints but decreased thickness of the Ag(s, s) and Cu(s, s) reaction layer and gradually thickened the Ti-Cu reaction layer near the TC4 side. The formation process of reaction products was discussed in detail. The holding time substantially influenced shear strength of the joints. A maximum shear strength of 39MPa was reached at a brazing time of 20min.

Effect of beam deviation on electron beam welded Ti-22Al-25Nb/TC4 dissimilar alloys

Dissimilar alloys of Ti-22Al-25Nb (at%) and TC4 are welded by electron beam welding (EBW), and the effect of different welding procedures (with electron beam deviation to TC4 side or without) on microstructure and mechanical properties of welded joints are investigated. Results show that the microstructure of fusion zone (FZ) consists of B2 phase and martensitic α′ phase. The heat-affected zone (HAZ) of Ti-22Al-25Nb side near FZ consists of B2 phase and a little of α2 phase, and that of TC4 side near FZ is the α′ phase. When the electron beam is deviated to TC4 side 0.15 mm during welding, the welded joint with good appearance of weld can be obtained, and the ultimate tensile strength and elongation of welded joint reach 967.6 MPa and 3.1%, respectively. The variation of microhardness in weld zone with beam deviation is smaller that of without beam deviation. Electron beam oscillation can stir fully the molten pool during welding, and the main alloying elements distribute uniformly in FZ. On the whole, the mechanical performance of welded joint with beam deviation is better than that of without beam deviation.

Microstructure and high-temperature mechanical properties of laser beam welded TC4/TA15 dissimilar titanium alloy joints

The microstructure evolution and high-temperature mechanical properties of laser beam welded TC4/TA15 dissimilar titanium alloy joints under different welding parameters were studied. The results show that the weld fusion zone of TC4/TA15 dissimilar welded joints consists of coarsened β columnar crystals that contain mainly acicular α′ martensite. The heat affected zone is composed of the initial α phase and the transformed β structure, and the width of heat affected zone on the TA15 side is narrower than that on the TC4 side. With increasing temperature, the yield strength and ultimate tensile strength of the TC4/TA15 dissimilar welded joints decrease and the highest plastic deformation is obtained at 800 °C. The tensile strength of the dissimilar joints with different welding parameters and base material satisfies the following relation (from high to low): TA15 base material > dissimilar joints > TC4 base material. The microhardness of a cross-section of the TC4/TA15 dissimilar joints reaches a maximum at the centre of the weld and is reduced globally after heat treatment, but the microhardness distribution is not changed. An elevated temperature tensile fracture of the dissimilar joints is located on the side of the TC4 base material. Necking occurs during the tensile tests and the fracture characteristics are typical when ductility is present in the material.

Microstructure and mechanical properties of electron beam welded TC4/TA7 dissimilar titanium alloy joint

Dissimilar titanium alloys TC4/TA7 are welded by using electron beam welding (EBW), and the microstructure and mechanical properties of welded joints are systematically investigated. Results show that the microstructure in different zones of welded joint is obviously different. The fusion zone (FZ) is mainly composed of fine α′ martensite. The heat-affected zone (HAZ) of TC4 side is composed of martensite, blocky α phase, original α phase and β phase. The HAZ of TA7 side consists of a small amount of martensite, blocky α phase and original α phase. TEM analysis shows that, due to the effect of modification welding, the martensite becomes coarser in the upper part of joint, and dislocations are generated in FZ. Element line scanning and elemental maps analyses indicate that the distribution of alloying elements is relatively uniform at joint interface, and no obvious segregation is occurred. The distribution of hardness in weld zones is ranked as follows: FZ > HAZ of TC4 side > TC4 base metal (BM) > HAZ of TA7 side > TA7 BM. The tensile strength of dissimilar joint is slightly higher than that of TA7 BM, while its elongation is slightly lower than those of the two BMs. The joint fails in the side of TA7 BM during stretching, and the morphology dominantly presents the characteristic of ductile fracture.

Microstructure and mechanical properties of TC4/0Cr18Ni9 joint prepared by transient liquid phase diffusion bonding

Because of significant difference in physical and chemical properties, the welding of titanium alloy and stainless steel is difficult. In order to solve the problems, TC4/0Cr18Ni9 joints were prepared by transient liquid phase (TLP) diffusion bonding using CuZn alloy as interlayer, and the microstructure, mechanical properties and bonding mechanism were studied and discussed. According to the morphological observation of interfaces and fracture surfaces, characterization of phases, tests of shear performance and micro hardness by scanning electron microscopy (SEM) with energy dispersive x-ray spectrometer (EDS), x-ray diffraction (XRD), universal testing machine, vickers micro-hardness tester and so on, CuZn alloy has good wettability and compatibility with TC4 and 0Cr18Ni9 as a interlayer material. Gradient structural joints are formed by sufficient element diffusion and reactions during TLP diffusion bonding. Compared with the interface bonding area adjacent 0Cr18Ni9 side, the joining area adjacent TC4 side is more continuous and denser without obvious defect. Hardness gradually increases from 0Cr18Ni9 side to diffusion reaction layer adjacent TC4, and then slightly reduces form diffusion reaction layer to TC4. The shear strength of TC4/0Cr18Ni9 joint can reach 146.4 ± 5.0 MPa and the fracture is not completely brittle. Ti2Cu and FeZn13 can be detected on the fracture surface of TC4/0Cr18Ni9 joint, which indicates fracture is apt to take place in the interface region adjacent 0Cr18Ni9 side.

Characterization of crystal structure in the bonding interface between TC17 and TC4 alloys

The Ti-5Al-2Sn-2Zr-4Mo-4Cr (TC17)/Ti-6Al-4 V (TC4) bonding interface at a bonding temperature of 820 °C, bonding pressure of 10 MPa and bonding time of 10 min was obtained, in which sufficient elemental diffusion occurred between TC17 and TC4. Special attention was paid to characterize the crystal structure in TC17/TC4 bonding interface via transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) techniques. The results showed that face-centered cubic titanium occurred in TC17 side of bonding interface, in which the face-centered cubic titanium and body-centered cubic titanium showed Kurdjumov-Sachs orientation relationship. Based on the orientation relationship and lattice parameter, the expansion of unit cell from body-centered cubic titanium to face-centered cubic titanium was about 2%. Besides, the disordered lattice appeared on the phase boundary between face-centered cubic titanium and hexagonal closed-packed titanium in TC4 side of bonding interface.

Dynamic Recrystallization-Related Interface Phase Boundary Migration of TC17/TC4 Bond with Initial Equiaxed Microstructure

The phase, grain, orientation and local misorientation in the bonding interface of a TC17/TC4 bond at different bonding times were carefully investigated via electron backscatter diffraction technique. Dynamic recrystallization (DRX) occurred in the primary α (αp)-enriched region of the TC4 side, in which large αp grains of the TC4 side transformed into small recrystallized α grains with random orientation. With the increasing of bonding time, DRX in the αp-enriched region of the TC4 side was more evident and the recrystallized α grains grew. The stored energy difference between the recrystallized α grains of the TC4 side and the β grains/subgrains of the TC17 side provided the driving force for the migration of the interface phase boundary (IPB). In addition, the migration of IPB was promoted as the bonding time increased, which was due to the synergistic effect of the increase in the stored energy difference and the growth of the recrystallized α grains of the TC4 side.

Interfacial voids, microstructure and shear strength of TC4/TC17 bond

TC4 (Ti-6Al-4V) and TC17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr) were solid-state bonded at the bonding temperatures ranging from 780-840℃, the bonding pressures ranging from 10 to 30 MPa and a bonding time of 30 min. Quantitative analysis of void size and bonding ratio was obtained based on scanning electron microscopy observation in the bonding interface of TC4/TC17 bonds. Electron backscatter diffraction examination in the bonding interface showed that the curved bond line due to the interpenetration between TC4 and TC17 driven by plastic flow occurred. Interfacial voids generally occurred on TC4 side or on the α(TC4)/α(TC17) interface grain boundary, which was due to faster material flow from β phase to interfacial voids than that from α phase under the effect of diffusion and plastic flow. The disappearance of large sized voids with the increasing of bonding pressure from 10 MPa to 20 MPa at 820℃, 30 min and the increasing of bonding temperature from 780℃ to 820℃ at 30 MPa, 30 min resulted in significant increase in shear strength of TC4/TC17 bonds. Besides, the TC4/TC17 bond at 840℃, 30 MPa and 30 min showed evidently deformed bond line and high shear strength of 756 MPa, which was due to enhanced interpenetration between TC4 and TC17 influenced by significant of α→β phase transformation on TC17 side.