Characterization And Heat Treatment Of Ti-6Al-4V Powders For Use In Cold Spray Deposition

Cold spray is a solid state deposition process which is attractive for a variety of applications including repair of metallic components. The process, however, relies on significant plastic deformation of the metal powder to achieve a dense coating. Consequently, depositing high strength materials, such as titanium alloys, is challenging. Feedstock powder microstructure is known to strongly influence cold spray deposition quality. We will report on the influence of feedstock powder microstructure on Ti-6Al-4V cold spray deposition quality. Several feedstock powders were characterized in as-received and heat treated condition using optical microscopy, scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy, and nanoindentation. Heat treatment was conducted to improve powder ductility and deposition quality. Three powders (i.e., gas atomized, plasma atomized and hydride de-hydride) were deposited using a high pressure cold spray system and the coating quality was compared with respect to porosity, tensile strength, ductility, hardness, and adhesion strength.