Microstructure and mechanical properties of Ti/Al laminates fabricated by ultrasonic additive manufacturing assisted by Joule heat and post-welding heat treatment

Abstract

In this study, a novel electrical-current assisted ultrasonic additive manufacturing (UAM) method was proposed and CP-Ti/Al3003 laminates were prepared by this process. The concept is that the Joule heat generated by the electrical current flowing through the CP-Ti foil is used to improve the material's plasticity, promote the interfacial bonding strength and continuous ultrasonic consolidation ability. Ti/Al laminates with excellent interfacial bonding strength and mechanical properties can be obtained by alternating the use of Ti foil and Al foil and subsequently applying post-welding heat treatment for interfacial strengthening. The current density distribution at the CP-Ti foil and Ti/Al interface was studied by finite element model. The interfacial microstructure of the laminates was characterized and analyzed by optical microscopy, scanning electron microscopy-energy dispersive spectroscopy, and X-ray diffraction, and the inhibition effect of current on the resonance cracking of Ti foil during the UAM process was verified. The effect of current on the interfacial bonding strength of the Ti/Al interface and the tensile strength of the laminates was investigated by peel test and tensile test. The growth kinetics of TiAl3 under the assisted current was also studied and CP-Ti/Al laminates with the tensile strength of 242.4 MPa in the rolling direction. The combined effect of Joule heating of current and subsequent post-weld heat treatment strengthened the reaction between Ti/Al and formed TiAl3 IMC layer and obtained CP-Ti/Al laminates without interface defects.