Nanophase precipitation strengthened Al alloys processed through the amorphous state

Abstract

Aluminum alloys having improved strength characteristics at elevated temperatures (300° C.) are manufactured by combining selected transition metals (Ni, Co, Ti, Fe, Y, Sc) and selected rare earth materials (Er, Tm, Tb, Lu) in amounts of about 2 to 12% and 2 to 15% atomic percent respectively in an amorphous, glassy state and subsequently devitrifying the amorphous material to form a crystalline mix of fcc and L1 2 phase material. Devitrification from the amorphous state may be effected by various means including thermal and thermo mechanical processes.

What is claimed is:  
     
         1 . An aluminum alloy characterized by high strength including high strength in the temperature range greater than about 250° C. comprising, in combination: 
 an alloy mixture in primarily crystalline form having at least about 30% by volume fcc phase and at least about 10% by volume L1 2  ductile precipitate phase, said alloy consisting essentially of at least one transition metal selected from the group consisting of about 2 to 12 atomic percent Ni, Co, Ti, Fe, Y, Sc, Cu, Zn, V, Cr, Mn and Li, and at least one rare earth material selected from the group consisting of about 2 to 15 atomic percent Er, Tm, Yb, Lu, and the balance Al.  
 
     
     
         2 . The alloy of  claim 1  further including Mg in an amount up to about 5% atomic fraction.  
     
     
         3 . The alloy of  claim 1  having a tensile strength of at least about 275 Mpa at 250° C.  
     
     
         4 . A method for manufacture of an aluminum alloy characterized by high strength including high strength in a temperature range greater than about 250° C. comprising the steps of: 
 (a) forming a melt mixture of aluminum, about 2 to about 12 atomic percent of at least one metal selected from the group consisting of Ni, Co, Ti, Fe, Y, Sc, Cu, Zn, V, Cr, Mn and Li, and at least one rare earth selected from the group consisting of about 2 to 15 atomic percent Er, Tm, Yb, and Lu;  
 (b) converting said melt to an amorphous state wherein the mixture comprises at least about 70% by volume amorphous material; and  
 (c) devitrifying said amorphous material to at least in part a crystalline matrix of at least about 30% by volume fcc and at least about 10% by volume L1 2  phase.  
 
     
     
         5 . The method of  claim 4  wherein the step of converting the melt comprises cooling in the range of at least about 10 3 ° C. per second.  
     
     
         6 . The method of  claim 4  wherein the step of devitrification is selected from a group consisting of thermoprocessing, thermomechanical processing and combinations thereof. A high temperature and high strength aluminum-based alloy processed through a primarily greater than about 70% in volume amorphous state and then devitrified into greater than about 70% in volume crystalline microstructure with fee matrix and strengthening by about a ductile L1 2  precipitate phase greater than about 10% L1 2 , and fcc greater than about 30% in volume.  
     
     
         7 . The method of  claim 4  wherein converting the melt comprises a step selected from the group consisting of gas powder atomization, water powder atomization, melt spinning, spray casting and combinations thereof.  
     
     
         8 . The method of  claim 4  wherein the step of devitrifying amorphous material comprises a step selected from the group consisting of hot isostatic pressing, thermal aging, extrusion and combinations thereof.  
     
     
         9 . An aluminum alloy characterized by high strength including high strength at a temperature greater than about 250° C. made by a process comprising the steps of: 
 (a) formulating a melt comprised of Al; at least one transition metal (TM) selected from the group consisting of Ni, Co, Ti, Fe, Y, Sc, Cu, Zn, V, Cr, Mn, Li and Mg; and at least one rare earth selected from the group consisting of Er, Tm, Yb, Lu;  
 (b) converting the melt to at least about 70% by volume amorphous material; and  
 (c) devitrifying at least in part the amorphous material to a mixture of fee and L1 2  crystalline precipitate phase material.  
 
     
     
         10 . The alloy product by the process of  claim 9  wherein the transition metal is provided in an amount of about 2 to 10 atomic percent.  
     
     
         11 . The alloy product by the process of  claim 9  wherein the rare earth material is provided in an amount of about 2 to 10 atomic percent.  
     
     
         12 . The alloy product by the process of  claim 9  further including an additive of Mg to the melt.  
     
     
         13 . The alloy product by the process of  claim 9  wherein devitrifying the amorphous material comprises forming at least about 30% by volume fcc material.  
     
     
         14 . The alloy product by the process of  claim 9  wherein devitrifying the amorphous material comprises forming at least 10% by volume L1 2  material.  
     
     
         15 . The alloy product by the process of  claim 9  wherein converting the melt to amorphous material comprises at least one step selected from the group consisting of gas powder atomization, water powder atomization and melt spinning.  
     
     
         16 . The alloy product by the process of  claim 9  wherein devitrification comprises at least one step selected from the group consisting of hot isostatic pressing, thermal aging, and extrusion.  
     
     
         17 . The method of  claim 4  wherein converting the melt comprises the step of rapid solidification processing.  
     
     
         18 . The product by the process of  claim 9  wherein converting the melt comprises rapid solidification processing.  
     
     
         19 . The alloy of  claim 1  or  claim 9  wherein the precipitate phase has a grain size diameter in the range of less than about 80 nm.