US 12,147,195 B2
Balance spring for a horological movement
Christian Charbon, Chézard-St-Martin (CH); Marco Verardo, Les Bois (CH); and Lionel Michelet, Fleurier (CH)
Assigned to NIVAROX-FAR S.A., Le Locle (CH)
Filed by Nivarox-FAR S.A., Le Locle (CH)
Filed on Jul. 23, 2020, as Appl. No. 16/936,682.
Claims priority of application No. 19198759 (EP), filed on Sep. 20, 2019.
Prior Publication US 2021/0088971 A1, Mar. 25, 2021
Int. Cl. G04B 17/06 (2006.01)
CPC G04B 17/066 (2013.01) [G04B 17/063 (2013.01)] 5 Claims
OG exemplary drawing
 
1. A balance spring (1) intended to equip a balance of a horological movement, characterised in that the balance spring (1) is made of a niobium and titanium alloy containing:
niobium: the remainder to 100 wt %;
titanium with a weight percentage that is greater than or equal to 1 wt % and less than 40 wt %,
traces of other elements chosen from one or more of O, H, C, Fe, Ta, N, Ni, Si, Cu and/or Al, each of said elements being in the range of 0 to 1,600 ppm of the total weight, and the sum of said trace elements being less than or equal to 0.3 wt %,
wherein the balance spring (1) has a two-phase microstructure comprising niobium in the beta phase form and titanium in the alpha phase form,
wherein the two-phase microstructure is composed of niobium in the beta phase form and titanium in the alpha phase form.