High entropy alloy for external components

Abstract

A high entropy alloy with a composition containing between 4 and 9 major alloying elements chosen from the list including Cr, Fe, V, Al, Si, Mn, Mo, Ti and Ni with: 3 major alloying elements which are Cr, Fe and V, each having an atomic concentration include between 20 and 40%, 1 or 2 major alloying elements chosen from Al and Si each having an atomic concentration higher than or equal to 5% with a total concentration of these 2 major alloying elements of less than or equal to 25%, 0, 1, 2, 3 or 4 major alloying elements chosen from Mn, Mo, Ti and Ni, each having an atomic concentration higher than or equal to 5% with a total atomic concentration of these 4 major alloying elements of less than or equal to 35%, the total atomic concentration of the 4 to 9 major alloying elements being higher than or equal to 80%, the remainder being made up of any impurities and/or one or more minor alloying elements, each in an atomic concentration of less than 5%.

Description

FIELD OF THE INVENTION[0001]The present invention concerns a high entropy alloy and an external component for a watch or piece of jewellery made from this alloy.PRIOR ART[0002]Various alloys are commonly used nowadays for the fabrication of external watch components which are components generally exposed to the external environment that may be in contact with the skin. These are, for example, austenitic stainless steels, titanium alloys or precious metals. Indeed, these alloys have certain important properties for this type of parts, namely high corrosion resistance, high polishability for aesthetic purposes, and no ferromagnetism. In addition to these characteristics, other properties are currently highly sought-after in horology. These characteristics are high biocompatibility, especially by reducing or eliminating potential allergens, such as nickel or cobalt, and a high hardness and scratch resistance. Alloys that meet all these criteria are rare. Precious metals have low hardne...

AI Technical Summary

Benefits of technology

[0008]Depending on the composition and thermomechanical treatments, the material obtained after implementation has a single-phase with a body-centred cubic structure, which promotes good corrosion resistance and high polishability for a better surface finish or, in the case of multi-phase alloys, a matrix (main phase) with a body-centred cubic structure reinforced by nanoprecipitates. It also has the advantage of having a colour close to that of austenitic stainless steels.

Problems solved by technology

Austenitic stainless steels generally contain nickel and also have limited hardness (<300 HV in annealed condition).

However, very specific implementations are required to obtain amorphous metal components, which further limits their use as external components.

However, they contain many elements that are expensive, very reactive or have high melting temperatures, such as Nb, Zr, Hf, Ta.

To facilitate the implementation of external timepiece components, it is important to avoid or limit the quantity of these elements, since high temperature resistance is not a desired property.

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