Microstructural analysis of Ti–6Al–4V powder for cold gas dynamic spray applications

• Three size-dependent external features have been found on plasma atomized particles.
• Chaotic martensite, basketweave α, and equiaxed α appear in powder cross-sections.
• Surface internal defects can include intermetallics, metastable phases, and pores.
• Control of powder structure, phase and morphology is critical for repeatability.

The importance of powder feedstock microstructure has been of relatively little interest in literature up until this point due to the melting or near melting processing conditions in most modern powder metallurgical techniques. The microstructure and resultant properties of consolidated materials in solid state processes, such as cold spray, are critically dependent on the feedstock powder. The focus of this paper is the characterization of plasma atomized Ti–6Al–4V powder using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Results indicate that while most powders are martensitic due to high cooling rates, powders can also have an equiaxed cellular or featureless microstructure depending on particle size.

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