Fe-ni-mn-al-cr alloys and methods for production thereof

Abstract

Alloys including iron, nickel, manganese, aluminum and chromium are disclosed. The alloys have high strength and ductility. The alloys are prepared from readily available transition metals, and can be used in applications where properties similar to steel are necessary or advantageous.

What is claimed is: 
     
         1 . An alloy comprising lamellae of a B2 ordered phase and lamellae of a face-centered cubic (f.c.c.) phase, wherein the average composition of the alloy comprises from 27% to 33% iron, 17% to 23% nickel, 32% to 38% manganese and 12% to 18% aluminum, and 2.5% to 5% chromium, wherein the composition is described in terms of atomic percentages. 
     
     
         2 . The alloy of  claim 1  wherein lamellae of the B2 ordered phase alternate with lamellae of the f.c.c. phase. 
     
     
         3 . The alloy of  claim 1 , wherein the average composition of the alloy comprises from 3% to 5% chromium. 
     
     
         4 . The alloy of  claim 1 , wherein the concentration of nickel and aluminum in the B2 phase is greater than the amount or iron or manganese and the concentration of iron and manganese in the f.c.c. phase is greater than the amount of nickel or aluminum. 
     
     
         5 . The alloy of  claim 1 , wherein the average thickness of the lamellae of the B2 phase is from 150 nm to 750 nm. 
     
     
         6 . The alloy of  claim 1 , wherein the average thickness of the lamellae of the B2 phase is from 150 nm to 500 nm. 
     
     
         7 . The alloy of  claim 1 , wherein the average thickness of the lamellae of the f.c.c. phase is from 200 nm to 2000 nm. 
     
     
         8 . The alloy of  claim 1 , wherein the average thickness of the lamellae of the f.c.c. phase is from 300 nm to 1000 nm. 
     
     
         9 . The alloy of  claim 1 , wherein the elongation to fracture of the chromium-containing alloy is from 10% to 15% as measured in air at room temperature at a strain rate of 5×10 −4  s −1 . 
     
     
         10 . An alloy comprising lamellae of a B2 ordered phase and lamellae of an f.c.c. phase, wherein the average composition of the alloy comprises from 27% to 33% iron, 17% to 23% nickel, 32% to 38% manganese and 12% to 18% aluminum, and greater than 5% to 7.5% chromium, wherein the composition is described in terms of atomic percentages. 
     
     
         11 . The alloy of  claim 10 , wherein lamellae of the B2 ordered phase alternate with lamellae of the f.c.c. phase. 
     
     
         12 . The alloy of  claim 10 , wherein the average composition of the alloy comprises 5.5% to 6.5% chromium. 
     
     
         13 . The alloy of  claim 10 , wherein the average composition of the alloy comprises 6% chromium. 
     
     
         14 . The alloy of  claim 10 , wherein the concentration of nickel and aluminum in the B2 phase is greater than the amount or iron or manganese and the concentration of iron and manganese in the f.c.c. phase is greater than the amount of nickel or aluminum. 
     
     
         15 . The alloy of  claim 10 , wherein the average thickness of the lamellae of the B2 phase is from 150 nm to 750 nm. 
     
     
         16 . The alloy of  claim 10 , wherein the average thickness of the lamellae of the B2 phase is from 150 nm to 500 nm. 
     
     
         17 . The alloy of  claim 10 , wherein the average thickness of the lamellae of the f.c.c. phase is from 200 nm to 2000 nm. 
     
     
         18 . The alloy of  claim 10 , wherein the average thickness of the lamellae of the f.c.c. phase is from 300 nm to 1000 nm. 
     
     
         19 . The alloy of  claim 10  wherein the elongation to fracture of the chromium-containing alloy is from 15% to 25% as measured in air at room temperature at a strain rate of 5×10 −4  s −1 .