Microstructure and mechanical properties of ultrasonically welded TA1/PEEK joint

Durable bonding between thermoplastics and metals plays a critical role in structural lightweighting. This study achieved ultrasonic welding of polyether ether ketone (PEEK) thermoplastic to laser-textured TA1 titanium alloy. Influence of the texturing space on microstructure and joint strength was investigated. Experimental results demonstrated that the texturing space was a major factor in joint strength, and the texturing spacing of 0.1 ​mm was superior than other texturing spacings. The maximum joint strength of 19.01 ​MPa was obtained at a texture spacing of 0.1 ​mm and an ultrasonic time of 6 ​s. Interfacial and cohesive failure mode was observed, and the fracture surface can be divided into two different parts: Cohesive failure region and Adhesive failure region. Cohesive failure dominated at smaller texturing spacings, while a progressive shift to adhesive failure occurred with increasing spacing. Laser texturing treatment significantly increased the TiO 2 content on TA1 surfaces, which facilitated the preferential formation of high-bond-energy Ti-C bonds between PEEK molecules and TA1, rather than Ti-O-C bonds. The joining mechanism in UW of PEEK to laser textured TA1 were mechanical interlocking and chemical bonding. Successful joining of Ti/PEEK dissimilar structure by ultrasonic welding appears to be a reliable and potential technique for industrial applications.