Structure and properties of a biomedical Co-Cr-Mo alloy produced by laser powder microdeposition

Laser powder microdeposition is a very promising technique to manufacture functional complex-shaped customized medical devices directly from a computer-aided design (CAD) file. It uses a finely focused laser beam to generate a small meltpool on the surface of a metallic substrate into which metallic powder is blown via a fine capillary. The laser/powder interaction zone is scanned over the substrate and molten material re-solidifies, leaving microscale tracks of deposited material. These tracks can be overlapped according to a previously established program to generate three-dimensional objects. The aim of the present work is to study the microstructure and properties of a typical Co-Cr-Mo biomedical alloy manufactured by laser powder microdeposition. In this paper, singles tracks of a biomedical Co-Cr-Mo alloy are deposited onto a 304 stainless steel substrate and a bulk part is fabricated by the successive overlapping of tracks. The deposited material is investigated by diffractometry, microscopy, and hardness testing, which revealed a homogenous microstructure comprised of fine cellular dendrites with a dispersion of intracellular precipitates and the presence of α and ε phases in the matrix. The fine morphology acts to engender significantly increased hardness values than those reported in Co-Cr-Mo parts fabricated by other processes.