Characterisation of Al–Ti dissimilar material joints fabricated using ultrasonic additive manufacturing

Abstract

Ultrasonic additive manufacturing (UAM) is a solid state manufacturing process for joining thin metal tapes using principles of ultrasonic metal welding. The process operates at low temperatures, enabling dissimilar material welds without generating harmful intermetallic compounds. In this study, a 9 kW UAM system was used to create joints of Al 1100 and commercially pure titanium. Viable process parameters were identified through pilot weld studies via controlled variation of weld force, amplitude and weld speed. Push-pin delamination tests and shear tests were performed, comparing as-built, heat treated and spark plasma sintering treated samples. Heat treated and spark plasma sintering treated samples yielded mechanical strengths over twice that of as-built samples. Electron backscatter diffraction measurements show that deformation and grain refinement only take place in the aluminium layers. Heat treated samples exhibit a thin intermetallic layer, which is hypothesised as constraining the interface, leading to the improved strength.

Design for Additive Manufacturing: Trends, opportunities, considerations, and constraints

“…For example, it is possible to create custom mixes of powders and binders [353], to alternate feedstock materials [81] [357], and to embed fibers [33][65] [67] in order to create in situ composites, increase mechanical strength, modify the thermal expansion coefficient [67], and obtain electrically tuneable stiffness [281]. Similarly, it is possible to control the porosity, microstructure, and material properties of metal, polymer, and ceramic parts through the choice of materials, process parameters, and build orientation [75][292] [353][362] [365].…”

“…Finally, postprocessing of finished parts can control and improve material properties. For example, heat treatment alters the grain structure and increases the mechanical strength of metal parts [164][349] [357] (Fig. 23).…”

Interface evolution and shear strength of Al/Ti bi-metals processed by a spark plasma sintering (SPS) apparatus

“…In our recent work [19], it was shown that SPS post-treatment of multilayered Al/Ti structures fabricated by UAM significantly improved their properties. To clarify the interface phenomena in the Al/Ti bi-metal, the kinetics of interfacial layer formation and its evolution during SPS processing were investigated in the present study.…”

Experimental study on ultrasonic consolidation process parameters of Ti-Al metal foil

“…The paper correlated measured weld power with the microstructure and mechanical properties of UAM parts (Hehr et al, 2016). Aluminum 1100 and pure titanium using a 9 kW ultrasonic additive manufacturing (UAM) system were consolidated, feasible process parameters by controlling welding force, the amplitude and welding speed were determined (Wolcott et al, 2016). The microstructure, lap shear strength, and hardness of AA2139-TiAl6V4 spot joints produced by ultrasonic welding were studied.…”