Nanostructured ferritic alloy and method of forming

Abstract

An alloy and method of forming the alloy are provided. The alloy includes a matrix phase, and a multimodally distributed population of particulate phases dispersed within the matrix. The matrix includes iron and chromium, and the population includes a first subpopulation of particulate phases and a second subpopulation of particulate phases. The first subpopulation of particulate phases include a complex oxide, having a median size less than about 15 nm, and present in the alloy in a concentration from about 0.1 volume percent to about 5 volume percent. The second subpopulation of particulate phases have a median size in a range from about 25 nm to about 10 microns, and present in the alloy in a concentration from about 0.1 volume percent to about 15 volume percent. Further embodiments include articles, such as turbomachinery components and fasteners, for example, that include the above alloy, and methods for making the alloy.

1 . An alloy, comprising:
 a matrix phase comprising iron and chromium; and a multimodally distributed population of particulate phases dispersed within the matrix, the population comprising:
 a first subpopulation of particulate phases comprising a complex oxide, having a median size less than about 15 nm, and present in the alloy in a concentration from about 0.1 volume percent to about 5 volume percent; and 
 a second subpopulation of particulate phases having a median size in a range from about 25 nm to about 10 microns, and present in the alloy in a concentration from about 0.1 volume percent to about 15 volume percent. 
   
     
     
         2 . The alloy of  claim 1 , wherein the particulate phases of the first subpopulation comprise at least two elements of the following group: yttrium, titanium, aluminum, zirconium, hafnium, and magnesium. 
     
     
         3 . The alloy of  claim 2 , wherein the particulate phases of the first subpopulation comprise yttrium and titanium. 
     
     
         4 . The alloy of  claim 1 , wherein the particulate phases of the first subpopulation have a median size less than about 10 nm. 
     
     
         5 . The alloy of  claim 1 , wherein the concentration of the first subpopulation is in an amount from about 0.1 volume percent to about 3 volume percent of the alloy. 
     
     
         6 . The alloy of  claim 1 , wherein the particulate phases of the second subpopulation have a median size in a range from about 25 nm to about 3 microns. 
     
     
         7 . The alloy of  claim 1 , wherein the concentration of the second subpopulation is in an amount from about 0.1 volume percent to about 6 volume percent of the alloy. 
     
     
         8 . The alloy of  claim 1 , comprising chromium in a range from about 5 weight percent to about 30 weight percent; titanium from about 0.1 weight percent to about 2 weight percent; and yttrium from about 0.1 weight percent to about 3 weight percent. 
     
     
         9 . The alloy of  claim 1 , wherein a concentration of total oxygen in the alloy is in a range from about 0.1 weight percent to about 0.6 weight percent of the alloy. 
     
     
         10 . An article comprising the alloy of  claim 1 , wherein the article comprises a turbomachinery component. 
     
     
         11 . An article comprising the alloy of  claim 1 , wherein the article comprises a fastener. 
     
     
         12 . The alloy of  claim 1 , wherein the particulate phases of the second subpopulation comprise an oxide. 
     
     
         13 . The alloy of  claim 12 , wherein the particulate phases of the second subpopulation comprise clusters of oxide subparticulates. 
     
     
         14 . The alloy of  claim 12 , wherein the oxide is a binary oxide. 
     
     
         15 . The alloy of  claim 14 , wherein the oxide comprises yttrium, titanium, aluminum, zirconium, hafnium, or magnesium. 
     
     
         16 . The alloy of  claim 12 , wherein the oxide is a complex oxide. 
     
     
         17 . The alloy of  claim 16 , wherein the complex oxide comprises at least two elements of the following group: yttrium, titanium, aluminum, zirconium, hafnium, and magnesium. 
     
     
         18 . The alloy of  claim 1 , wherein the particulate phases of the second subpopulation comprise a precipitated Laves phase. 
     
     
         19 . The alloy of  claim 18 , wherein the Laves phase comprises molybdenum, niobium, magnesium, iron, zinc, nickel, copper, or any combination of the foregoing. 
     
     
         20 . The alloy of  claim 1 , wherein the particulate phases of the second subpopulation comprise a precipitated mu phase. 
     
     
         21 . The alloy of  claim 20 , wherein the mu phase comprises molybdenum, niobium, magnesium, iron, zinc, nickel, copper, or any combination of the foregoing. 
     
     
         22 . The alloy of  claim 1 , wherein the particulate phases of the second subpopulation comprise a precipitated carbide, nitride, or carbonitride phase. 
     
     
         23 . The alloy of  claim 1 , wherein the particulate phases of the second subpopulation comprise a precipitated intermetallic phase having a Ni 3 M structure, wherein M comprises titanium, aluminum, molybdenum, niobium, tantalum, tungsten or any combination of the foregoing. 
     
     
         24 . The alloy of  claim 1 , wherein the second subpopulation comprises an added oxide phase comprising yttrium, aluminum, zirconium, magnesium, hafnium, or any combination of the foregoing. 
     
     
         25 . The alloy of  claim 1 , wherein the second subpopulation comprises an added boride phase comprising chromium, titanium, niobium, tantalum, or any combination of the foregoing. 
     
     
         26 . The alloy of  claim 1 , wherein the particulate phases of the second subpopulation comprise a precipitated Laves or mu phase; and a non-precipitated oxide or boride phase. 
     
     
         27 . The alloy of  claim 1 , wherein the particulate phases of the second subpopulation comprise a precipitated carbide, nitride, carbonitride, or an intermetallic phase having a Ni 3 M structure; and a non-precipitated oxide or boride phase. 
     
     
         28 . An article, comprising:
 an alloy comprising a matrix phase comprising iron and chromium, and a multimodally distributed population of particulate phases dispersed within the matrix, the population comprising:
 a first subpopulation of particulate phases comprising a complex oxide comprising yttrium and titanium, having a median size less than about 10 nm, and present in the alloy in a concentration from about 0.1 volume percent to about 5 volume percent; and 
 a second subpopulation of particulate phases comprising a precipitated Laves phase, having a median size in a range from about 50 nm to about 3 microns, and present in the alloy in a concentration from about 1 volume percent to about 6 volume percent. 
   
     
     
         29 . An article, comprising:
 an alloy comprising a matrix phase comprising iron and chromium, and a multimodally distributed population of particulate phases dispersed within the matrix, the population comprising:   a first subpopulation of particulate phases comprising a complex oxide comprising yttrium and titanium, having a median size less than about 15 nm, and present in the alloy in a concentration from about 0.1 volume percent to about 5 volume percent; and   a second subpopulation of particulate phases comprising an oxide, having a median size in a range from about 25 nm to about 100 nm, and present in the alloy in a concentration from about 0.1 volume percent to about 5 volume percent.   
     
     
         30 . A method of forming an alloy, comprising:
 melting starting materials comprising iron and chromium;   atomizing the melt to form an alloy powder;   milling the alloy powder in the presence of an oxide until the oxide is at least partially dissolved into the alloy powder, thus forming a milled alloy powder;   consolidating the milled alloy powder at a first temperature;   precipitating a first subpopulation of particulate phases comprising a complex oxide having a median size less than about 15 nm; and   establishing a second subpopulation of particulate phases having a median size in a range from about 25 nm to about 10 microns.   
     
     
         31 . The method of  claim 30 , wherein a concentration of the first subpopulation of particulate phases is in a range from about 0.1 volume percent to about 5 volume percent of the alloy. 
     
     
         32 . The method of  claim 30 , wherein a concentration of the second subpopulation of particulate phases is in a range from about 0.1 volume percent to about 15 volume percent of the alloy. 
     
     
         33 . The method of  claim 30 , wherein the precipitated particulate phases of the first subpopulation comprise at least two elements of the following group: yttrium, titanium, aluminum, zirconium, hafnium, and magnesium. 
     
     
         34 . The method of  claim 30 , wherein establishing the second subpopulation comprises dispersing within the milled alloy powder undissolved particles of the oxide to form the particulate phases of the second population. 
     
     
         35 . The method of  claim 34 , wherein the particulate phases of the second subpopulation comprise an oxide comprising yttrium, titanium, aluminum, zirconium, hafnium, or magnesium. 
     
     
         36 . The method of  claim 30 , wherein establishing the second subpopulation comprises an in-situ precipitation in the consolidated, milled alloy powder. 
     
     
         37 . The method of  claim 36 , wherein the particulate phases of the second subpopulation comprise a Laves phase. 
     
     
         38 . The method of  claim 36 , wherein the particulate phases of the second subpopulation comprise a mu phase. 
     
     
         39 . The method of  claim 36 , wherein the particulate phases of the second subpopulation comprise a carbide, nitride, or carbonitride phase. 
     
     
         40 . The method of  claim 36 , wherein the particulate phases of the second subpopulation comprise an intermetallic phase having a Ni 3 M structure, wherein M comprises titanium, aluminum, molybdenum, niobium, tantalum, or any combination of the foregoing. 
     
     
         41 . The method of  claim 36 , wherein establishing the second subpopulation comprises an in-situ precipitation by heat-treating the consolidated, milled alloy powder at a second temperature. 
     
     
         42 . The method of  claim 41 , wherein the consolidated, milled alloy powder is hot-worked before in-situ precipitation of the second subpopulation by heat-treating. 
     
     
         43 . The method of  claim 41 , wherein the second temperature is in a range from about 550° C. to about 850° C. 
     
     
         44 . The method of  claim 30 , wherein establishing the second subpopulation comprises mechanically mixing the milled alloy powder with an added particulate phase. 
     
     
         45 . The method of  claim 44 , wherein the added particulate phase comprises an oxide, boride, or a combination of oxide and boride. 
     
     
         46 . The method of  claim 30 , wherein establishing the second subpopulation comprises a combination of in-situ precipitating of the consolidated, milled alloy powder; and mechanically mixing an added particulate phase to the milled alloy powder. 
     
     
         47 . The method of  claim 30 , wherein establishing the starting materials comprises a vacuum induction melting process. 
     
     
         48 . A method of forming an alloy, comprising:
 melting starting materials comprising iron and chromium through a vacuum induction melting process;   atomizing the melt to form an alloy powder;   milling the alloy powder in the presence of an oxide to dissolve oxide into the alloy powder, thus forming a milled alloy powder;   consolidating the milled alloy powder at a first temperature precipitating a first subpopulation of particulate phases comprising a complex oxide comprising yttrium and titanium, having a median size less than about 20 nm, in a concentration from about 0.1 volume percent to about 3 volume percent of the alloy;   hot-working the consolidated, milled alloy powder; and   heat-treating the hot-worked, consolidated, milled alloy powder at a second temperature and establishing a second subpopulation of particulate phases by an in-situ precipitation of a Laves phase having a median size in a range from about 30 nm to about 10 microns, in a concentration from about 1 volume percent to about 4 volume percent of the alloy.   
     
     
         49 . A method of forming an alloy, comprising:
 melting starting materials comprising iron and chromium through a vacuum induction melting process;   atomizing the melt to form an alloy powder;   milling the alloy powder in the presence of an oxide to dissolve oxide into the alloy powder, thus forming a milled alloy powder;   adding a particulate phase comprising an oxide, boride, or a combination of an oxide and boride to the milled alloy powder, and mixing;   consolidating the milled and mixed alloy powder at a first temperature precipitating a first subpopulation of particulate phases comprising a complex oxide comprising yttrium and titanium, having a median size less than about 20 nm, in a concentration from about 0.1 volume percent to about 3 volume percent of the alloy; and   establishing a second subpopulation of particulate phases resulting from the added particulate phase in the consolidated, milled, and mixed alloy powder, wherein the second subpopulation has a median size in a range from about 30 nm to about 10 microns, and present in the alloy in a concentration from about 1 volume percent to about 4 volume percent.   
     
     
         50 . A method of forming an alloy, comprising:
 melting starting materials comprising iron and chromium through a vacuum induction melting process;   atomizing the melt to form an alloy powder;   milling the alloy powder in the presence of an oxide until the oxide is partially dissolved into the alloy powder, thus forming a milled alloy powder;   establishing a second subpopulation of particulate phases by dispersing within the milled alloy powder undissolved particles of the oxide to form the particulate phases of the second population, wherein the second subpopulation has a median size in a range from about 25 nm to about 10 microns, and is present in the alloy in a concentration from about 0.1 volume percent to about 15 volume percent; and   consolidating the milled alloy powder at a first temperature precipitating a first subpopulation of particulate phases comprising a complex oxide comprising yttrium and titanium, having a median size less than about 15 nm, in a concentration from about 0.1 volume percent to about 5 volume percent of the alloy.