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The Micro-Electrical Discharge Machining (Micro-EDM) technique has been employed to machine micro-patterns with shaped micro-slots on Ti6Al4V surfaces. Ti6Al4V substrates, with and without micro-slots, were bonded using a commercial epoxy adhesive. Optical microscopy and SEM were used to observe the micro-patterned Ti6Al4V surfaces before and after joining and to analyse the fracture surfaces after mechanical tests. The joints were mechanically characterised, with and without micro-patterns, by means of Single Lap Offset (SLO) shear tests under compression to understand the effect of differently shaped micro-slots. The effects of the shape of the micro-slots, their interlocking or overlapping, and their orientation, with respect to the applied load, are presented and discussed in terms of mechanical performance of the joints.

Monolithic high purity CVD β-SiC materials were successfully joined with a pre-sintered Ti 3 SiC 2 foil via solid-state diffusion bonding. The initial bending strength of the joints (∼ 220 MPa) did not deteriorate at 1000 °C in vacuum, and the joints retained ∼ 68 % of their initial strength at 1200 °C. Damage accumulation in the interlayer and some plastic deformation of the large Ti 3 SiC 2 grains were found after testing. The activation energy of the creep deformation in the temperature range of 1000 – 1200 °C in vacuum was ∼ 521 kJmol −1 . During the creep, the linkage of a significant number of microcracks to form a major crack was observed in the interlayer. The Ti 3 SiC 2 interlayer did not decompose up to 1300 °C in vacuum. A mild and well-localized decomposition of Ti 3 SiC 2 to TiC x was found on the top surface of the interlayer after the bending test at 1400 °C in vacuum, while the inner part remained intact.

Active solder alloy 92Sn3Ag3Ti was used to join Al2O3 ceramic on cast A356 aluminum alloy substrate using an ultrasonic assisted soldering process. Due to the large discrepancy in thermal shrinkage coefficients between materials, large thermal stresses occur during cooling down to room temperature. Further cooling to −78 °C and −196 °C was used to inflict additional thermal stress in the samples. Shear strength, image analysis of fractured surfaces and microstructure analysis were performed to study the influence of cooling. Ceramic samples with different surface finish were used to investigate the influence of the contact between ceramic and aluminum alloy substrate on the fracture behavior. Two types of failure were observed, a detachment of the solder alloy from the ceramic surface and a cohesive failure through the solder layer. The results show that cooling the joined sample to −78 °C does not significantly affect the bonding strength of the samples. However, samples that were rapidly cooled to −196 °C showed reduced shear strengths even when the amount of cohesive failure area was taken into account. Many newly formed cracks in the Sn matrix were observed in the joint after the cooling which were identified as strength-determining defects. Keywords: Active soldering, Shear strength, Fracture, Ceramic, Aluminum