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Microstructural,mechanical and corrosion properties of two simple cast nickel-based alloys derived froma real dental alloy employed in prosthetic dentistry

Lyndho Princilia Billy Nsoungui, Patrice Berthod

Manymetallic pieces used in prosthetic dentistry aremade of very expensive metals such as gold, platinum, palladium or silver, to guarantee absence of any corrosion phenomena. Much cheaper alloys presenting high ductility and resistance, and simultaneously high corrosion resistance, exists and are of great interest. This is the case of {nickel-chromium}-based alloys containing heavy elements as molybdenum for good mechanical properties and rich enough in chromiumto ensure the development of a very protective chromia passivation layer. Other elements such Si orAlmay be also present. The purpose of this work is first to study themicrostructure, mechanical and corrosion role of silicon in a nickel-based chromium-rich alloy inspired from a commercial dental alloy.Casting,microstructure characterization,mechanical test by indentation and compression, and electrochemical corrosion experiments were carried out for a Si-free and a Si-containing Ni-25.7Cr- 11Mo alloys, with also consideration to a possible hardened state by preliminary plastic deformation. The Si effect of Si on the mechanical properties was significant, but not its influence on the corrosion behaviour. This may be due to the very high initial corrosion resistance of these alloys.