Impulse pressuring diffusion bonding (IPDB) of TiC cermet to stainless steel 06Cr19Ni10 using Ti-Nb interlayer was carried out in an attempt to reduce the bonding time and to alleviate the detrimental effect of interfacial reaction products on bonding strength. Successful bonding is achieved at 890 °C under a pulsed pressure of 2∼10 MPa within a duration of only 4∼12 min, which is notably shortened in comparison with conventional diffusion bonding. Microstructure characterization reveals the existence of σ phase with a limit solubility of Nb, (β-Ti, Nb) phase, and solid solution of Ni in α + β-Ti in the reaction zone. Maximum shear strength of 110 MPa is obtained when the joint is bonded for 10 min, indicating a robust metallurgical bonding is achieved. Upon shear loading, the joints fracture along the remnant Ti/α + β-Ti interface and extend to the interior of TiC cermet in a brittle cleavage manner. This technique provides a highly promising bonding method of TiC cermet and steel.

The three-stage isothermal solidification process of TLP bonded Mar-M247 nickel-based superalloy was studied. The transient liquid phase bonding of Mar-M247 superalloys was conducted at 1150 °C for 1, 60, 120 and 240 min. Dendritic formation and solute partitioning governed the microstructure development. Ni-rich solid solution, Ni-rich boride W-rich boride and other carboborides were formed in the joint area. The maximum tensile strength of 443 MPa was obtained when TLP bonding at 1150 °C for 240 min. It had completed isothermal solidification. After isothermal solidification, the distribution of microhardness across the joints was more homogeneous. Enrichment of refractory elements in the Ni-Cr-Co-W-Ta-B interlayer was detrimental to the process of isothermal solidification. The presence of hard and brittle borides reduced the hardness and tensile strength of the bonded area. Post-bonding heat treatments are suggested to improve mechanical properties in future studies.

Tungsten inert gas (TIG) welding–brazing technology using Mg-based filler was developed to join AZ31B Mg alloy to TC4 Ti alloy in a lap configuration. The results indicate that robust joints can be obtained with welding current in the range of 60–70 A. The joint interface was found to be likely composed of Mg–Ti diffusion reaction layer accompanied with Mg17Al12 precipitate phase, indicating that metallurgical joining was achieved. The optimized joint with average tensile-shear strength of 190 N/mm2 was obtained and fracture occurred at the Ti/fusion zone interfacial layer during tensile test. Moreover, the fracture surface was characterized by equiaxed dimple patterns accompanied with a few lamellar tearing. Finally, finite element modeling (FEM) numerical simulation was developed to analyze the distribution characteristics of the temperature field of joints.

Vacuum diffusion bonding of TiC cermet/304 stainless steel (304SS) was conducted and Ti-Nb-Cu multi-interlayer was used to achieve active bonding and residual stress relieving. Detailed microstructure characterization and mechanical property assessment were carried out to evaluate the bonding technology. It is found that an obvious transition zone is formed at the interfaces, and the interfacial products are (Ti, Nb), remnant Nb, remnant Cu and Cu(s.s). The shear strength of TiC/Ti-Nb-Cu/304SS joint can be up to 84.6 MPa when it is bonded at 925 °C for 20 min under a pressure of 8 MPa. Failure occurs in TiC cermet near the interface in a brittle manner. The results indicate that Ti/Nb/Cu interlayer can effectively reduce the harmful effects of intermetallic compounds on the joint performance, and the Nb interlayer plays a major role in the relief of the residual stress.

In the present study, impulse pressuring diffusion bonding technology (IPDB) was utilized between commercially pure titanium and 304 stainless steel (SS) using pure nickel (Ni) as interlayer metal. The interfacial microstructures of the bonded joints were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscope (EDS) analyses. It is found that with the aid of the Ni interlayer, the interdiffusion and reaction between Ti and SS can be effectively restricted and robust joints can be obtained. Intermetallic compounds (IMCs) including Ti2Ni, TiNi, and TiNi3 are detected at the Ti/Ni interface; however, only Ni–Fe solid solution is found at the Ni/SS interface. The maximum tensile strength of 358 MPa is obtained by IPDB for 90 s and the fracture takes place along the Ti2Ni and TiNi phase upon tensile loading. The existence of cleavage pattern on the fracture surface indicates the brittle nature of the joints.

•A Nb containing CuNiMn filler metal was devised for the joining of TiC cermet/steel.•Nb was thermodynamically favorable in promoting the TiC/filler interfacial reaction.•Robust metallurgical bonding was achieved by forming Nb2C/Nb6C5/αTi transition zone.•Maximum shear strength of 92.5 MPa was approached.A Nb containing Cu–Ni–Mn brazing filler was developed for the joining of TiC cermet to steel. Interfacial microstructural investigations of the brazed joint and associated thermodynamic analysis of TiC and niobium carbides were carried out. It was found that Nb was thermodynamically favorable in promoting the decomposition of the TiC, and thus facilitated the TiC/filler interfacial reaction. A transition zone (~5 μm) consisting of Nb2C/Nb6C5/αTi was formed at the filler/TiC interface, indicating a robust metallurgical bonding was achieved. Maximum shear strength of 92.5 MPa was approached, which indicated that the Cu–Ni–Mn–Nb was highly promising for the joining of TiC to steel.

An alloy foil of rapidly solidified Sn-9Zn-0.1Cr was produced by the melt-spinning technique. The mechanical properties of the Cu/Sn-9Zn-0.1Cr/Cu joints prepared by the rapidly solidified and the as-solidified solders were investigated. The results showed that the fracture of the joints took place at the interface region between the intermetallic compound (IMC) layer and the solder. Granular IMCs in the size of about 2–3 μm formed in the interface. While using the rapidly solidified Sn-9Zn-0.1Cr solder, fine needle-like Cu5Zn8 phases crystallized on the surface of the granular Cu5Zn8 IMCs. The solderability of the rapidly solidified alloy was much better than that of the as-solidified solders. By comparison with as-solidified Sn-9Zn and Sn-9Zn-0.1Cr solders, the tensile-shear strength of the joint by use of the rapidly solidified Sn-9Zn-0.1Cr solder improved by about 50% and 30%, respectively.Highlights► Rapidly solidified Sn-9Zn-0.1Cr foils are produced by melt-spinning method. ► Effects of solders on the properties of the solder/Cu joints are studied. ► Rapidly solidified Sn-9Zn-0.1Cr alloy exhibits good solderability. ► Joint strength is improved markedly by using rapidly solidified Sn-9Zn-0.1Cr.

Rapidly solidified Sn-9Zn-0.1Cr alloy foils were obtained by the melt-spinning method. The solder characteristics of this rapidly solidified alloy were analyzed and compared with those of as-solidified Sn-9Zn and Sn-9Zn-0.1Cr alloys. The mechanical properties of Cu/solder/Cu joints obtained using these alloys were comparatively investigated. Compared with the as-solidified Sn-9Zn and Sn-9Zn-0.1Cr alloys, the melting point of the rapidly solidified Sn-9Zn-0.1Cr alloy was lower by about 9°C and its wettability was better. The microstructure of the soldering seam was notably fine and the intermetallic compound (IMC) layer became relatively uniform using the rapidly solidified Sn-9Zn-0.1Cr solder. The tensile shear strengths of the joints using the rapidly solidified solder were markedly higher than those of the joints using the as-solidified solders. The former exhibited good solderability and excellent joint strength. The improved properties of the joints might result from the formation of fine-grained IMCs with a needle pattern and more uniform IMC layer at the interface.

Ultrasonic vibration with different powers from 0 kW to 1.6 kW was applied during the tungsten inert gas welding-brazing of Mg/Ti. The microstructures, mechanical properties and corrosion resistance of the ultrasonic assisted tungsten inert gas (U-TIG) welded-brazed Mg/Ti joint were characterized. The results showed that, without being subjected to ultrasonic vibration, coarse columnar α-Mg grains occurred in the fusion zone of Mg/Ti joint. However, with ultrasonic power of 1.2 kW, the average grain size of columnar α-Mg grains was refined from 200 µm to about 50 µm and the tensile strength of joints increased ~18% up to 228 MPa. Besides, high fraction of grain boundaries was introduced by grain refinement, contributing to improve the corrosion resistance in two ways: (i) accelerating the formation of Mg(OH)2 protective layer and (ii) reducing the mismatch and disorder between Mg(OH)2 protective layer and Mg alloy surface.