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This review aims to evaluate high-entropy and biodegradable alloys for orthopedic and cardiovascular implants, focusing on their controlled degradation properties.

April 28, 2026Discover Materials1 citationsOpen Access

High entropy and biodegradable alloy strategies for biomedical implants with controlled degradation

DADare Victor Abere SOSammy A. OjoUniversity of Akron OAOjoma Helen AdejoRochester Institute of Technology

Key Points

This review aims to evaluate high-entropy and biodegradable alloys for orthopedic and cardiovascular implants, focusing on their controlled degradation properties.
Examining recent developments in biodegradable high-entropy alloys (BHEAs) and their mechanical and corrosion properties.
Constructing a degradation-rate and elastic-modulus safe operating window for load-bearing implants using in-vitro data from various alloy types.
Linking phase characteristics and degradation aspects to biofunctionality and mechanical resilience in implants.
BHEAs demonstrate high corrosion resistance and biofunctionality compared to traditional alloys like Ti-6Al-4 V and Co–Cr.
Proposed designs of BHEAs emphasize the importance of phase compositions and contamination in achieving ideal structural and biological performance.
A design matrix connects microstructural features of alloys to their degradation rates and mechanical properties, ensuring safety in biomedical applications.

Abstract

High-entropy alloys (HEAs) and biodegradable metallic systems represent emerging frontiers in biomaterials for orthopedic, cardiovascular, and tissue-regenerative applications. Conventional Ti-6Al-4 V and Co–Cr alloys offer high strength but suffer from stress shielding, adverse ion release, and the need for removal surgery. Bio-high-entropy alloys (Bio-HEAs) based on multi-principal, non-toxic elements (Ti, Zr, Nb, Ta, Hf) provide bone-like modulus, high strength, and superior corrosion resistance, whereas Mg-, Zn- and Fe-based biodegradable alloys are designed to resorb after fulfilling their structural role. This review examines how these trajectories converge in biodegradable high-entropy alloys (BHEAs), which seek to couple entropy-stabilized microstructures with controlled, bio-benign degradation and ion-mediated biofunctionality. Beyond summarizing recent developments, it introduces a mechanistic design matrix linking phase-potential gaps, phase topology, porosity and corrosion-product characteristics to corrosion morphology and ion-dose profiles in candidate BHEAs. A degradation-rate–elastic-modulus “safe operating window” for temporary load-bearing implants is constructed by aggregating representative in-vitro corrosion and mechanical data from Mg-, Zn-, Fe-based alloys and Ti-centered Bio-HEAs. The review explicitly distinguishes experimentally supported observations from forward-looking design hypotheses, including Ti/Zr/Nb/Ta-rich matrices coupled to finely dispersed Mg/Zn-rich sacrificial phases and architected implants enabled by additive manufacturing, providing a convergence-focused framework beyond existing Bio-HEA and biodegradable alloy reviews.

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