Gas-phase alloying of metallic materials

Abstract

A direct manufacturing technique involving rapid solidification processing uses a reaction between a metallic molten pool and a reactant gas in an inert atmosphere to form alloys with improved desired properties. By utilizing rapid solidification techniques, solubility levels can be increased resulting in alloys with unique mechanical and physical properties. Laser deposition of alloys in atmospheres of varying reactant content produce significant strengthening without cracking. In addition, these materials have very high hardness values for hard face coating and functionally graded materials applications.

1 . A method of forming an alloy, comprising: 
 (a) providing a heat source and a metallic feedstock in a gaseous atmosphere;    (b) delivering a gaseous alloying element proximate to the metallic feedstock;    (c) converging the heat source on the metallic feedstock and the gaseous alloying element;    (d) melting the metallic feedstock with the heat source to form a molten pool such that the metallic feedstock alloys with the gaseous alloying element to form a composition; and    (e) cooling and solidifying the composition.    
   
   
       2 . The method of  claim 1 , wherein the gaseous atmosphere is approximately 70% to 99.9% inert gas, and approximately 0.1% to 30% gaseous alloying element.  
   
   
       3 . The method of  claim 1 , wherein the gaseous alloying element is selected from the group consisting of nitrogen and oxygen.  
   
   
       4 . The method of  claim 1 , wherein the heat source is a laser that is directed by fiber optics.  
   
   
       5 . The method of  claim 1 , wherein the heat source is selected from the group consisting of an electron beam and an electron arc.  
   
   
       6 . The method of  claim 1 , further comprising the step of controlling the heat source with optics, the optics also being mounted to a movable platform, and wherein the movable platform is computer-controlled to position the heat source and the metallic feedstock in a desired location for multiple sections and layers of a part being formed.  
   
   
       7 . The method of  claim 1 , wherein step (e) comprises forming a part with adjacent, side-by-side layers to form a width of the part, and adjacent, stacked layers to form a height of the part.  
   
   
       8 . A method of forming an alloy, comprising: 
 (a) providing a laser heat source, a movable platform, and a metallic feedstock in a gaseous atmosphere;    (b) delivering a gaseous alloying element proximate to the metallic feedstock on the movable platform;    (c) converging the laser heat source on the metallic feedstock and the gaseous alloying element;    (d) melting the metallic feedstock with the laser heat source to form a molten pool on the movable platform, such that the metallic feedstock alloys with the gaseous alloying element to form a composition; and    (e) moving the composition via the movable platform and the heat source relative to each other, such that the molten pool rapidly cools and solidifies to form a continuous line of deposited alloy to form a part.    
   
   
       9 . A method according to  claim 8 , wherein the gaseous atmosphere is approximately 70% to 99.9% inert gas, and approximately 0.1% to 30% gaseous alloying element.  
   
   
       10 . A method according to  claim 8 , wherein the gaseous alloying element is selected from the group consisting of nitrogen and oxygen.  
   
   
       11 . A method according to  claim 8 , further comprising the step of controlling the laser heat source with optics, the optics also being mounted to the movable platform, and wherein the movable platform is computer-controlled to position the laser heat source and the metallic feedstock in a desired location for multiple sections and layers of the part being formed.  
   
   
       12 . A method according to  claim 8 , wherein step (e) comprises forming the part with adjacent, side-by-side layers to form a width of the part, and adjacent, stacked layers to form a height of the part.