High entropy alloy, method of preparation and use of the same

Abstract

A high entropy alloy includes at least five elements selected from Cobalt, Nickel, Titanium, Zirconium, and Hafnium, wherein two of the five elements have a total atomic percentage of 100−x, and the remainder elements have a total atomic percentage of x, where 0<x<100. A method of producing the high entropy alloy. A component for use in a mechanical timepiece. The component is made of the high entropy alloy.

1 . A high entropy alloy comprising at least five elements selected from Cobalt, Nickel, Titanium, Zirconium, and Hafnium, wherein two of the five elements have a total atomic percentage of 100−x, and the remainder elements have a total atomic percentage of x, where 0<x<100. 
     
     
         2 . The high entropy alloy of  claim 1 , wherein the high entropy alloy is represented by a chemical formula of (CoNi) 100−x (HfTiZr) x , where x is an atomic percentage and 0<x<100. 
     
     
         3 . The high entropy alloy of  claim 1 , wherein the high entropy alloy is represented by a chemical formula of (CoNi) 100−x (HfTiZr) x , where 45≤x≤55. 
     
     
         4 . The high entropy alloy of  claim 1 , wherein the high entropy alloy has an elastic module that is substantially constant with respect to a temperature change from 300K to 900K. 
     
     
         5 . The high entropy alloy of  claim 1 , wherein the high entropy alloy comprises a body centred cubic (BCC) structure. 
     
     
         6 . The high entropy alloy of  claim 5 , wherein atoms of the high entropy alloy are accommodated within the BCC structure by atomic-scale chemical ordering. 
     
     
         7 . The high entropy alloy of  claim 1 , wherein the high entropy alloy comprises a distorted lattice structure. 
     
     
         8 . The high entropy alloy of  claim 1 , wherein the high entropy alloy has an atomic size difference of about 11%. 
     
     
         9 . The high entropy alloy of  claim 1 , wherein the high entropy alloy has an elastic limit of about 2%. 
     
     
         10 . A method of preparing the high entropy alloy of  claim 1 , comprising the steps of:
 preparing an alloy precursor by arc melting a predetermined amount of raw materials of each elements constituting the high entropy alloy in an inert atmosphere; and   casting the melted alloy precursor into a cooled mold to obtain the high entropy alloy.   
     
     
         11 . The method of  claim 10 , wherein the raw materials comprises Cobalt, Nickel, Titanium, Zirconium, and Hafnium. 
     
     
         12 . The method of  claim 11 , wherein the raw materials are in atomic percentages of: 0-50% Cobalt, 0-50% Nickel, 0-33.3% Titanium, 0-33.3% Zirconium, and 0-33.3% Hafnium. 
     
     
         13 . The method of  claim 10 , wherein the raw materials have a purity of >99.9%. 
     
     
         14 . The method of  claim 10 , further comprising the step of flipping and remelting the alloy precursor in a repetitive manner. 
     
     
         15 . The method of  claim 10 , wherein the arc melting is conducted under a Ti-gettered argon atmosphere with a pressure below 8×10 −4  Pa. 
     
     
         16 . The method of  claim 10 , wherein the mold is a copper mold. 
     
     
         17 . The method of  claim 16 , wherein the copper mold is a cylinder or a plate. 
     
     
         18 . The method of  claim 17 , wherein the cylindrical copper mold has a diameter of 5 mm and a length of 100 mm. 
     
     
         19 . The method of  claim 17 , wherein the plate copper mold has a dimension of 5×10×60 mm 3 . 
     
     
         20 . A component for use in a mechanical timepiece, wherein the component is made of the high entropy alloy of  claim 1 . 
     
     
         21 . The component of  claim 20 , wherein the component is a mainspring and/or a hairspring. 
     
     
         22 . The component of  claim 20 , wherein the mechanical timepiece is selected from the list comprising mechanical watches, mechanical chronometers, and marine chronometers.