Abstract:
Bioimplants are susceptible to simultaneous wear and corrosion degradation in
the aggressive physiological environment. High entropy alloys with equimolar proportion of
constituent elements represent a unique alloy design strategy for developing bioimplants due
to their attractive mechanical properties, superior wear, and corrosion resistance. In this study,
the tribo-corrosion behavior of an equiatomic MoNbTaTiZr high entropy alloy consisting of
all biocompatible elements was evaluated and compared with 304 stainless steel as a
benchmark. The high entropy alloy showed a low wear rate and a friction coefficient as well as
quick and stable passivation in simulated body fluid. An increase from room temperature to
body temperature showed excellent temperature assisted passivity and nobler surface layer of
the high entropy alloy, resulting in four times better wear resistance compared to stainless
steel. Stem cells and osteoblast cells displayed proliferation and migratory behavior, indicating
in vitro biocompatibility. Several filopodia extensions on the cell periphery indicated early
osteogenic commitment, and cell adhesion on the high entropy alloy. These results pave the
way for utilizing the unique combination of tribo-corrosion resistance, excellent mechanical
properties, and biocompatibility of MoNbTaTiZr high entropy alloy to develop bioimplants with improved service life and lower risk
of implant induced cytotoxicity in the host body.
