Ultrasonic additive manufacturing: metallic interlayer for bonding titanium and other incompatible metals

The problem

Conventional Ultrasonic Additive Manufacturing (UAM), a solid-state process that bonds metal layers using ultrasonic vibrations, cannot reliably bond certain metals, most notably titanium. Titanium's exceptional material properties limit its plastic deformation, which is the fundamental mechanism UAM relies on to create bonds. In practice, titanium pieces fracture, tear, or fail to bond, rendering titanium largely unusable in conventional UAM workflows despite its high value in the aerospace, defense, medical, and automotive industries.

The solution

Researchers at the University of Tennessee have developed and patented (US12551970B2) a novel metallic interlayer method that enables the successful UAM of titanium and other metals previously incompatible with conventional UAM processes. The technology features the deposition of vanadium onto a titanium surface prior to UAM bonding, only requiring about half a second without melting, treatment, and no bulk chemical changes to the titanium itself. The method has been successfully demonstrated on both commercially pure titanium and Ti-6Al-4V — the industry-standard titanium alloy used across aerospace and medical applications. The same approach can also be extended to other difficult-to-process metals, making this a broadly applicable platform technology.

Benefits

• Enables reliable bonding of commercially pure titanium and Ti-6Al-4V alloy, materials previously incompatible with UAM.
• Only a minor amount of interlayer material is needed, keeping the process cost-effective.
• The interlayer principle extends to other hard-to-bond metals, enabling a wide range of similar and dissimilar metal combinations.
• Solid-state, low-temperature process, wherein bonding occurs without bulk melting, preserving material properties and reducing energy consumption.
• Compatible with existing UAM equipment, thus requiring no redesign of existing manufacturing infrastructure.
• Underlying principle extends to other hard-to-process metals (e.g., zirconium, magnesium) and enables new combinations of dissimilar metals.

Patent status

US 12,551,970.