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Carbon- and Platinum-Modified Co-Cr Alloys for Thin-Strut Stents

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Abstract:

Percutaneous coronary intervention (PCI) is a minimally invasive treatment for ischemic heart disease, commonly supported by balloon-expandable stents to prevent arterial restenosis. Stent materials must combine high ultimate tensile strength, high ductility, low 0.2% proof strength, high corrosion resistance, high X-ray visibility, and magnetic susceptibility close to that of human soft tissues. The Co-20Cr-15W-10Ni (mass%) alloy, standardized as ASTM F90 and commonly referred to as L605 is widely employed for this purpose. Recently, the demand for stents with smaller diameters and thinner struts has grown, as these significantly lower restenosis risk. Alloys for thin-strut stents therefore require exceptional mechanical and physical performance. This paper reviews the microstructures and mechanical and physical properties of the carbon- and Pt-modified Co-Cr-W-Ni alloys developed by our group. The Co-20Cr-15W-10Ni-0.2C (mass%) alloy achieved an excellent strength–ductility balance and a low 0.2% proof strength owing to the γ-stabilizing effect of carbon. First-principles calculations further revealed that carbon addition increases stacking fault energies (SFEs) in Co-Cr alloys. Pt-modified Co-Cr alloys exhibited higher X-ray visibility than L605 and greater strength than Pt-Cr steel while maintaining comparable ductility. Collectively, these results indicate that carbon- and Pt-modified Co-Cr alloys are promising candidates for next-generation balloon-expandable stents, particularly thin-strut designs.

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Journal of Biomimetics, Biomaterials and Biomedical Engineering Vol. 72 View Preview

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Periodical:

Journal of Biomimetics, Biomaterials and Biomedical Engineering (Volume 72)

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21-29

DOI:

https://doi.org/10.4028/p-KhM0G9

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Online since:

May 2026

Authors:

Takayuki Narushima*, Sukma Suci Friandani, Tomoki Nakajima, Kyosuke Ueda, Ryoji Sahara, Alfirano Alfirano

Keywords:

Biomaterials, Co-Cr-W-Ni Alloy, First-Principles Calculation, Mechanical Property, Stacking Fault Energy, X-Ray Visibility

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© 2026 Trans Tech Publications Ltd. All Rights Reserved

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* - Corresponding Author

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