High-entropy alloy, and method for producing the same
A high-entropy alloy having ultra-high strength and high hydrogen embrittlement resistance due to formation of a microstructure at a low strain may be produced without a severe plastic deformation. A method for producing the high-entropy alloy includes (a) annealing and homogenizing an initial alloy material at 1000 to 1200° C. for 1 to 24 hours; and (b) rolling the annealed and homogenized initial alloy material into a rod, at a cryogenic temperature of −100 to −200° C. while pressing the initial alloy material in multi-axial directions at a strain of 0.4 to 1.2, thereby to produce the high-entropy alloy having intersecting twins as a microstructure, and secondary fine twins formed in the intersecting twins, wherein the initial alloy material contains Co of 5 to 35%, Cr of 5 to 35%, Fe of 5 to 35%, Mn of 5 to 35%, and Ni of 5 to 35%, based on weight %.
1. A method for producing a high-entropy alloy, the method comprising:
(a) annealing and homogenizing an initial alloy material at 1000 to 1200° C. for 1 to 24 hours; and
(b) rolling the annealed and homogenized initial alloy material into a cylindrical rod, thereby to produce a high-entropy alloy having intersecting twins as a microstructure, and secondary fine twins formed in the intersecting twins,
wherein the initial alloy material contains Co of 5 to 35%, Cr of 5 to 35%, Fe of 5 to 35%, Mn of 5 to 35%, and Ni of 5 to 35%, based on weight %, and
wherein the rolling into the cylindrical rod is performed with a multi-pass caliber-roller having circular holes of different diameters at a cryogenic temperature of −100 to −200° C. in multi-axial directions.
2. The method of claim 1 , wherein the rolling into the cylindrical rod is performed at a strain of 0.4 to 1.2.
3. The method of claim 1 , wherein the (b) includes:
(b1) forming primary twins as the intersecting twins; and
(b2) forming the secondary fine twins inside a line of the intersecting twins.
4. The method of claim 1 , wherein an average size of a fine grain due to the intersecting twins and the secondary fine twins is in a range of 30 to 150 nm.
5. The method of claim 1 , wherein the high-entropy alloy has a FCC (face-centered cubic) single-phase structure.