Timepiece component containing a high-entropy alloy

Abstract

The invention concerns a timepiece component containing a high-entropy alloy, the high-entropy alloy containing between 4 and 13 main alloying elements forming a single solid solution, the high-entropy alloy having a concentration of each main alloying element comprised between 1 and 55 at. %.

Claims

1. A timepiece component, comprising: a high-entropy alloy, wherein the high-entropy alloy is formed of multiple metallic elements forming a single-phase structure, and the high-entropy alloy satisfies formula Ta.sub.aNb.sub.bHf.sub.cZr.sub.dCr.sub.e, where a, b, c, d, and e are each a value independently ranging from 1 to 55 at. %.

2. The timepiece component according to claim 1, wherein the high-entropy alloy comprises one or more interstitial elements selected from the group consisting of C, N, and B.

3. The timepiece component according to claim 1, wherein the high-entropy alloy comprises one or more structural hardening elements selected from the group consisting of Ti, Al, Be, and Nb.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages of the present invention will appear more clearly in the following detailed description of preferred embodiments, given by way of non-liming examples with reference to the appended Figures, in which:

(2) FIG. 1 schematically represents a mainspring according to one embodiment of the invention;

(3) FIG. 2 schematically represents the steps of a method for fabricating a mainspring according to one embodiment of the invention.

DETAILED DESCRIPTION

(4) FIG. 1 schematically represents a mainspring 1 according to one embodiment of the invention. This mainspring 1 is made of a high-entropy alloy.

(5) In such a high-entropy alloy, the entropy of mixing is high and makes the single phase more thermodynamically stable than the mixing of several phases.

(6) The mainspring is preferably made from the high-entropy alloy described in the publication ‘Metastable high-entropy dual-phase alloys overcome the strength-ductility trade-off’, Zhiming Li et al, Nature 534, 227-230 (9 Jun. 2016). This high-entropy alloy has the following formula: Fe.sub.80-xMn.sub.xCo.sub.10Cr.sub.10. x is preferably comprised between 25 and 79 at. %.

(7) More precisely, according to a first embodiment, the mainspring may be made from a Fe.sub.35Mn.sub.45Co.sub.10Cr.sub.10 alloy. The mainspring produced in this manner has the advantage of combining high tensile strength and high ductility.

(8) According to a second embodiment, the mainspring may be made from a Fe.sub.40Mn.sub.40Co.sub.10Cr.sub.10.alloy. The spring produced in this manner has the advantage of high tensile strength and high ductility. It also operates according to a TWIP (twinning induced plasticity) mechanism.

(9) According to a third embodiment, the mainspring may be made from a Fe.sub.45Mn.sub.35Co.sub.10Cr.sub.10.alloy. The mainspring produced in this manner has the advantage of having even higher tensile strength and higher ductility. It also operates according to a TRIP (transformation induced plasticity) mechanism.

(10) According to a fourth embodiment, the mainspring can be made from a Fe.sub.50Mn.sub.30Co.sub.10Cr.sub.10 alloy. The mainspring produced in this manner has the advantage of having even higher tensile strength and higher ductility. It operates according to a TRIP mechanism with the appearance of two phases, FCC and HCP, by a twinning mechanism.

(11) The invention is not limited to fabrication of a mainspring. Indeed, other timepiece components could be fabricated from the high-entropy Fe.sub.80-xMn.sub.xCo.sub.10Cr.sub.10 alloy, such as a spring, a staff, an impulse pin, a balance, an arbor, a roller, pallets, a pallet lever, a pallet fork, an escape wheel, a shaft, a pinion, a an oscillating weight, a winding stem, a crown, a jumper spring, a watch case, a bracelet link, a watch bezel, a bracelet clasp . . . .

(12) FIG. 2 schematically represents the steps of a method for fabricating the mainspring of FIG. 1.

(13) This method includes a first step 101 of fabricating a high-entropy alloy ingot. To do so, the elements are mixed in pure or pre-alloy form, they are then melted, and the mixture is cast to form an ingot.

(14) The method then includes a step 102 of hot forging the ingot.

(15) The method then includes a hot lamination step 103.

(16) The method then includes a cold lamination step 104.

(17) The method then includes a wire drawing step 105.

(18) The method then includes a cold lamination step 106.

(19) Naturally, the invention is not limited to the embodiments described with reference to the Figures and variants could be envisaged without departing from the scope of the invention.

(20) Thus, in the preceding examples, the Fe.sub.80-x Mn.sub.xCo.sub.10Cr.sub.10 alloy was used. However, other high-entropy alloys could be used, such as, for example: Fe.sub.20Mn.sub.20Ni.sub.20Co.sub.20Cr.sub.20, Fe.sub.40Mn.sub.27Ni.sub.26Co.sub.5Cr.sub.2, Ta.sub.20Nb.sub.20Hf.sub.20Zr.sub.20Ti.sub.20, Al.sub.20Li.sub.20Mg.sub.10Sc.sub.20Ti.sub.30, Cr.sub.18.2Fe.sub.18.2Co.sub.18.2Ni.sub.18.2Cu.sub.18.2Al.sub.9.0.