Composite material having a layer including entrained particles and method of making same

Abstract

A composite material suitable for use as an armor includes a first layer of a metallic material and a second layer, metallurgically bonded with the first layer. The second layer includes a matrix of the material of the first layer and a plurality of brittle particles dispersed in the matrix. A method for making a composite structure suitable for use as an armor from a workpiece of a metallic material includes the steps of plasticizing a fractional thickness of the workpiece using a friction stir process, introducing a plurality of brittle particles into the plasticized, fractional thickness of the workpiece, and dispersing the plurality of brittle particles into the plasticized, fractional thickness of the workpiece using the friction stir process.

1 . A composite material suitable for use as an armor, comprising:
 a first layer comprising:
 a metallic material; and 
   a second layer, metallurgically bonded with the first layer, the second layer comprising:
 a matrix of the material of the first layer; and 
 a plurality of brittle particles dispersed in the matrix. 
   
     
     
         2 . The composite material, according to  claim 1 , wherein the metallic material has a specific gravity of at least about four grams per cubic centimeter. 
     
     
         3 . The composite material, according to  claim 1 , wherein the metallic material of the first layer comprises:
 a material selected from the group consisting of titanium and titanium alloys.   
     
     
         4 . The composite material, according to  claim 1 , wherein at least some of the plurality of brittle particles comprises:
 a material selected from the group consisting of ceramic, carbide, tungsten carbide, and titanium carbide.   
     
     
         5 . The composite material, according to  claim 1 , wherein the plurality of brittle particles has an average sieve size within a range of about 0.5 micron to about 80 microns. 
     
     
         6 . The composite material, according to  claim 1 , wherein the plurality of brittle particles comprises:
 a volume fraction of the second layer within a range of about one percent to about 30 percent.   
     
     
         7 . The composite material, according to  claim 1 , wherein the second layer exhibits an average grain size that is less than an average grain size exhibited by the first layer. 
     
     
         8 . The composite material, according to  claim 1 , wherein the second layer is a mixture of the plurality of particles and the matrix. 
     
     
         9 . The composite material, according to  claim 1 , wherein the composite material forms an armor. 
     
     
         10 . The composite material, according to  claim 1 , wherein the armor comprises:
 a portion of a vehicle.   
     
     
         11 . The composite material, according to  claim 1 , wherein the second layer is formed by a friction stir processing method. 
     
     
         12 . The composite material, according to  claim 1 , wherein the structure is formed by a method comprising the steps of:
 engaging a rotating, non-consumable tool with a precursor comprising the metallic material of the first layer to plasticize a fractional thickness of the precursor, leaving a remaining fractional thickness of the precursor unplasticized;   introducing the plurality of brittle particles into the plasticized, fractional thickness of the precursor;   dispersing the plurality of brittle particles into the plasticized, fractional thickness of the precursor; and   traversing the rotating, non-consumable tool across the precursor, such that the plasticized, fractional thickness of the precursor with the plurality of brittle particles dispersed therein forms the second layer and the remaining unplasticized thickness of the precursor forms the first layer.   
     
     
         13 . A composite material, according to  claim 1 , wherein a thickness of the second layer is within a range of about two percent of a total thickness of the composite structure to about 20 percent of the total thickness of the composite structure. 
     
     
         14 . An armor, comprising:
 a first layer made of a material selected from the group consisting of titanium and titanium alloys; and   a second layer metallurgically bonded to the first layer, the second layer comprising:
 a matrix made of the material of the first layer; and 
 a plurality of particles dispersed in the matrix. 
   
     
     
         15 . The armor, according to  claim 14 , wherein at least some of the plurality of particles comprises:
 a material selected from the group consisting of ceramic, carbide, tungsten carbide, and titanium carbide.   
     
     
         16 . The armor, according to  claim 14 , wherein the armor forms a portion of a vehicle. 
     
     
         17 . The armor, according to  claim 14 , wherein the armor is operably associated with a vehicle. 
     
     
         18 . The armor, according to  claim 14 , wherein the second layer is formed by a friction stir processing method. 
     
     
         19 . The armor, according to  claim 14 , wherein the armor is formed by a method comprising the steps of:
 engaging a rotating, non-consumable tool with a precursor comprising the material of the first layer to plasticize a fractional thickness of the precursor, leaving a remaining fractional thickness of the precursor unplasticized;   introducing the plurality of brittle particles into the plasticized, fractional thickness of the precursor;   dispersing the plurality of brittle particles into the plasticized, fractional thickness of the precursor; and   traversing the rotating, non-consumable tool across the precursor, such that the plasticized, fractional thickness of the precursor with the plurality of brittle particles dispersed therein forms the second layer and the remaining unplasticized thickness of the precursor forms the first layer.   
     
     
         20 . A method for making a composite structure suitable for use as an armor from a workpiece of a metallic material, the method comprising the steps of:
 plasticizing a fractional thickness of the workpiece using a friction stir process;   introducing a plurality of brittle particles into the plasticized, fractional thickness of the workpiece; and   dispersing the plurality of brittle particles into the plasticized, fractional thickness of the workpiece using the friction stir process.   
     
     
         21 . The method, according to  claim 19 , further comprising the step of:
 refining the grain structure of the plasticized, fractional thickness of the workpiece using the friction stir process.   
     
     
         22 . The method, according to  claim 19 , wherein the friction stir process comprises the steps of:
 engaging a rotating, non-consumable tool with the workpiece; and   traversing the tool across the workpiece.   
     
     
         23 . The method, according to  claim 19 , wherein the step of introducing the plurality of brittle particles is accomplished by introducing the plurality of brittle particles at a specified rate to produce a volume fraction of brittle particles dispersed in the plasticized, fractional thickness of the workpiece within a range of about one percent to about 30 percent. 
     
     
         24 . The method, according to  claim 19 , wherein the step of dispersing the plurality of brittle particles further comprises the step of:
 mixing the plurality of brittle particles and the plasticized, fractional thickness of the workpiece.   
     
     
         25 . The method, according to  claim 18 , wherein the fractional thickness is within a range of about two percent of a total thickness of the workpiece to about 20 percent of the total thickness of the workpiece.