Iron-containing alloys and associated systems and methods

Abstract

Iron-containing alloys, and associated systems and methods, are generally described. The iron-containing alloys are, according to certain embodiments, nanocrystalline. According to certain embodiments, the iron-containing alloys have high relative densities. The iron-containing alloys can be relatively stable, according to certain embodiments. Inventive methods for making iron-containing alloys are also described herein. The inventive methods for making iron-containing alloys can involve, according to certain embodiments, sintering nanocrystalline particulates comprising iron and at least one other element (e.g., at least one other metal or a metalloid) to form an iron-containing nanocrystalline alloy.

What is claimed is: 
     
         1 - 51 . (canceled) 
     
     
         52 . A method of forming a nanocrystalline metal alloy, comprising:
 sintering a plurality of nanocrystalline particulates to form the nanocrystalline metal alloy;   wherein at least some of the nanocrystalline particulates comprise Fe and a second element, and wherein:
 Fe is the most abundant element by atomic percentage in at least some of the nanocrystalline particulates; and/or 
 sintering the plurality of nanocrystalline particulates involves heating the nanocrystalline particulates to a first sintering temperature that is greater than or equal to 500° C. and less than or equal to 1100° C. for a sintering duration greater than or equal to 6 hours and less than or equal to 24 hours; and/or 
 sintering the plurality of nanocrystalline particulates involves heating the nanocrystalline particulates such that the nanocrystalline particulates are not at a temperature of greater than or equal to 1100° C. for more than 24 hours; and/or 
 the second element and Fe exhibit a miscibility gap. 
   
     
     
         53 - 57 . (canceled) 
     
     
         58 . A method of forming a metal alloy, comprising:
 sintering powder comprising Fe and Mg to produce the metal alloy, wherein the metal alloy has a relative density of greater than or equal to 80%.   
     
     
         59 . The method of  claim 52 , wherein the second element is a second metal. 
     
     
         60 . (canceled) 
     
     
         61 . The method of  claim 52 , wherein the Fe and the second element are present in a non-equilibrium phase. 
     
     
         62 . The method of  claim 52 , wherein the non-equilibrium phase undergoes decomposition during the sintering. 
     
     
         63 . The method of  claim 52 , wherein the non-equilibrium phase undergoes decomposition during the sintering, and the decomposition of the non-equilibrium phase accelerates a rate of sintering of the nanocrystalline particulates. 
     
     
         64 . The method of  claim 52 , wherein the non-equilibrium phase comprises a supersaturated phase comprising the second element dissolved in Fe. 
     
     
         65 . The method of  claim 52 , wherein the second element is selected from the group consisting of magnesium (Mg), boron (B), zirconium (Zr), gold (Au), chromium (Cr), nickel (Ni), vanadium (V), platinum (Pt), lead (Pb), copper (Cu), cobalt (Co), and tin (Sn). 
     
     
         66 . The method of  claim 52 , wherein the second element is Mg. 
     
     
         67 . The method of  claim 52 , further comprising cold pressing the plurality of nanocrystalline particulates during at least one portion of time prior to the sintering. 
     
     
         68 . (canceled) 
     
     
         69 . The method of  claim 52 , wherein the cold pressing comprises cold compression of the plurality of nanocrystalline particulates at a force greater than or equal to 300 MPa and less than or equal to 1400 MPa. 
     
     
         70 . The method of  claim 52 , wherein the sintering comprises heating the nanocrystalline particulates to a first sintering temperature lower than a second sintering temperature needed for sintering Fe in the absence of the second element. 
     
     
         71 . The method of  claim 52 , wherein the sintering comprises heating the nanocrystalline particulates to a temperature greater than or equal to 600° C. and less than or equal to 1100° C. for a duration greater than or equal to 6 hours and less than or equal to 24 hours. 
     
     
         72 . (canceled) 
     
     
         73 . The method of  claim 52 , wherein the non-equilibrium phase comprises a solid solution. 
     
     
         74 . The method of  claim 52 , further comprising forming at least some of the nanocrystalline particulates by mechanically working a powder comprising Fe and the second element. 
     
     
         75 . The method of  claim 52 , further comprising forming at least some of the nanocrystalline particulates by ball milling a powder comprising Fe and the second element. 
     
     
         76 . The method of  claim 52 , wherein at least some of the nanocrystalline particulates have a grain size of smaller than or equal to 50 nm. 
     
     
         77 - 78 . (canceled) 
     
     
         79 . The method of  claim 52 , wherein the second element is present in the nanocrystalline particulates in an amount of less than or equal to 30 at % of the nanocrystalline particulates. 
     
     
         80 - 84 . (canceled) 
     
     
         85 . The method of  claim 52 , wherein the nanocrystalline metal alloy has a relative density of at least 90%. 
     
     
         86 . The method of  claim 52 , wherein the sintering further comprises forming a second phase at at least one of a surface and a grain boundary of the nanocrystalline particulates during the sintering. 
     
     
         87 . The method of  claim 52 , wherein the sintering further comprises forming a second phase at at least one of a surface and a grain boundary of the nanocrystalline particulates during the sintering; and the second phase is rich in the second element. 
     
     
         88 . The method of  claim 52 , wherein the nanocrystalline metal alloy has a first grain size and a sintered material comprising Fe in the absence of the second element has a second grain size, the first grain size being smaller than the second grain size. 
     
     
         89 . (canceled) 
     
     
         90 . The method of  claim 52 , wherein the sintering is conducted essentially free of external applied stress. 
     
     
         91 . (canceled) 
     
     
         92 . A nanocrystalline metal alloy produced by the method of  claim 52 . 
     
     
         93 . (canceled) 
     
     
         94 . The method of  claim 52 , wherein for at least 20% of the time during which sintering is performed, the maximum external pressure applied to the nanocrystalline particulates is less than or equal to 2 MPa. 
     
     
         95 . The method of  claim 52 , wherein the sintering is pressureless sintering.