Tailoring titanium alloys toward processing by wire-arc directed energy deposition

Description

The development of novel metal alloys tailored for additive manufacturing has been a research focus in recent years. While substantial progress has been presented using powder-based processes, relatively few efforts have been made using wire feedstock (such as in use in wire-arc directed energy deposition) and most of the literature in this field deals with commercial welding wires, i.e., mostly Ti-6Al-4V. Due to the unique processing conditions prevailing during wire-arc directed energy deposition, several challenges arise including (a) formation of large primary grains; (b) solidification and subsequent phase transformation texture formation including variant selection; (c) anisotropic mechanical properties. Therefore, new alloy concepts need to be developed that can overcome these problems. Addition of alloying elements favoring constitutional supercooling such as Cu, Ni or Fe has been suggested. These elements also form intermetallic phases via an eutectoid reaction.
In the present work, we investigate the effects of various binary, ternary and quaternary alloying systems with the aim of modifying the solidification conditions toward a fine and untextured microstructure. Another focus is on the subsequently occurring solid-state phase transformations. Microstructural analysis is performed using electron microscopy, X-ray diffraction and atom probe tomography with thermodynamic calculations aiding our understanding of the phase formation sequences. Mechanical properties are assessed using microhardness measurements and compression tests.
The comprehensive analyses presented in this work suggests that the solidification microstructure can be favorably modified by alloying element additions and that the eutectoid transformation can be used to tailor the resultant microstructure. As a result, extremely fine microstructures can be produced. The resulting mechanical properties are significantly higher than those of conventional reference alloys.

Period	11 Jul 2023
Event title	10th International Light Metals Technology Conference (LMT2023)
Event type	Conference
Location	AustraliaShow on map