Oxidation resistant high-entropy alloys
Disclosed herein are new face-centered cubic (f.c.c.) high-entropy alloys with compositions (in atomic %) of Fe a Ni b Mn c Al d Cr e C f where a is between 37-43 atomic %, b is between 8-14 atomic %, c is between 32-38 atomic %, d is 4.5-10.5 atomic %, e is between 2.5-9 atomic % and f is between 0-2 atomic %. The undoped alloy has strength of 159 MPa and 40% elongation to failure, but the doped, carbon-containing alloy having 1.1 atomic percent carbon has yield strength of 360 MPa, an ultimate tensile strength (UTS) of 1200 MPa and 50% elongation to failure at room temperature. At 700° C., the yield strength is 214 MPa with 24% elongation to failure. Thus, the present alloy may replace austenitic stainless steels in applications where better strength is needed at both room temperature and elevated temperature in an oxidation resistant alloy.
1. A high-entropy alloy (HEA) having a formula of Fe a Ni b Mn c Al d Cr e C f where a is 37-43 atomic %, b is 8-14 atomic %, c is 32-38 atomic %, d is 5-10.5 atomic %, e is 5-9 atomic % and f is 0-2 atomic %.
2. The HEA of claim 1 , wherein f is between 0.5 and 1.1 atomic %.
3. The HEA of claim 1 having the formula Fe 40.42 Ni 11.28 Mn 34.78 Al 7.52 Cr 6 , wherein the composition is expressed in terms of atomic percentages.
4. The HEA of claim 1 having the formula Fe 39.9 Ni 10.4 Mn 35.6 Al 7.4 Cr 5.6 C 1.1 , wherein the composition is expressed in terms of atomic percentages.
5. The HEA of claim 1 , wherein the HEA has a face centered cubic structure.
6. The HEA of claim 1 , wherein the HEA is a solid solution.
7. The HEA of claim 6 , wherein the solid solution comprises interstitial carbon atoms.
8. The HEA of claim 1 , wherein the HEA has a yield strength of at least 350 MPa at room temperature.
9. The HEA of claim 1 , wherein the HEA has an ultimate tensile strength (UTS) of at least 1200 MPa at room temperature.
10. The HEA of claim 1 , wherein the HEA has an elongation to failure of at least 50% at room temperature.
11. A composition comprising the high-entropy alloy of claim 1 .
12. The composition of claim 11 further comprising one or more intermetallic carbide particles having a formula independently selected from the group consisting of M 23 C 6 and M 7 C 3 , wherein M is independently selected from the group consisting of Fe, Ni, Mn, Al and Cr.