Interdiffusion of Elements During Ultrasonic Additive Manufacturing

This paper reports evidence for enhanced elemental interdiffusion during ultrasonic additive manufacturing (UAM) across metal boundaries of copper-aluminum, nickel-gold, and nickel-gold-aluminum. The high solute interdiffusion measured by energy dispersive X-ray spectroscopy line scans is rationalized with calculated vacancy concentrations orders of magnitude larger than thermal equilibrium values. The above estimates are supported by existing knowledge related to defect physics and UAM thermal cycles. The observation of pronounced elemental mixing are evidence for the presence of enhanced non-equilibrium immiscible metal interdiffusion during UAM processing.