The design of prostheses for maxillo-facial restoration requires careful selection of materials
with desirable biocompatible properties as the patient often has a large wound from trauma or
infection. Medical grade ASTM F75 Co-Cr-Mo alloys are the hardest known biocompatible
materials commonly used in medical implants, partial denture frameworks, and crown & bridge
substructure restorations in dentistry. The primary choice of Co-Cr-Mo alloys for dental
applications is due to their excellent mechanical and tribological properties. However, the
toxicity and the cost due to the higher concentration of Cobalt (Co) is a major concern. In the
present work, an attempt is made to invent a novel low-cost CoCrMoFe alloy composition with
considerable reduction in the concentration of Cobalt by the addition of Iron (Fe) which can
also be printable by Laser powder bed fusion-based additive manufacturing process. The
designed alloy is envisaged to possess reduced toxicity potential and excellent mechanical,
biocorrosion and tribological properties compared to commercially used expensive CoCrMo
alloys.
The alloy composition is developed using the Calphad approach, and optimum printing
parameters using a grid search approach are used to develop a robust set of process parameters
for producing CoCrMoFe alloy parts with minimal defects and imperfections with required
dimensional accuracy. Subsequent to this, non-destructive testing and cross-sectioning are used
for estimating the porosity in the manufactured samples; thus, the sets of laser power and
appropriate ranges for scanning speeds for the production of solid, non-porous samples are
invented. Mechanical properties of as-built CoCrMoFe alloy samples are studied and compared
to medical grade ASTM F75 Co-Cr-Mo alloy as a function of build orientations. The tensile
strength and yield strength are found to have significantly improved by Fe addition in
CoCrMoFe alloy as compared to conventional Co-Cr-Mo alloys. Vickers hardness analysis of
CoCrMoFe alloy showed a 30 % improvement in the hardness value as compared to medical
grade ASTM F75 Co-Cr-Mo alloy. The preliminary corrosion studies have showed improved
corrosion resistance in Co-Cr-Mo-Fe alloy as compared to Co-Cr-Mo alloy. Summarily, CoCr-Mo-Fe alloy has displayed its potential to become a superior alternative to the traditional
Co-Cr-Mo alloy for the additive manufacturing of fixed dental restorations.
Keywords: Laser Powder Bed Fusion (LPBF); Maxillofacial Implant; Alloy development.