Method and system for enhancing the quality of deposited metal

Abstract

Systems and methods are disclosed to effectively fracture dendrite arms and/or reduce grain size in a solidifying metal melt pool. Ultrasonic energy is applied to the solidifying metal in the liquid metal pool directly or via a substrate on which the metal is provided. In another embodiment, ultrasonic energy is applied over a range of frequencies and/or tuned to the resonant frequency of solidifying dendrite arms. Advantageously, the present invention prevents or hinders the growth of large columnar dendrites and instead allows for the formation of a high density of randomly oriented grains with a reduction in grain size, thereby enhancing the quality of the deposited metal and therefore improving the mechanical properties of the fabricated or repaired structure.

1 . A system for enhancing the quality of deposited metal, comprising: 
 a metal deposition apparatus that provides liquid metal on a substrate; and    an ultrasonic energy source operably coupled to the metal deposition apparatus such that ultrasonic energy is applied to solidifying metal in the liquid metal.    
   
   
       2 . The system of  claim 1 , wherein the metal deposition apparatus provides liquid metal via laser engineered net shaping, direct metal deposition, or electron beam melting.  
   
   
       3 . The system of  claim 1 , wherein the liquid metal is selected from the group consisting of nickel, cobalt and iron-based superalloys, steels, copper, aluminum, titanium, niobium, molybdenum, tungsten, rhenium, and alloys thereof.  
   
   
       4 . The system of  claim 1 , wherein the ultrasonic energy source is selected from the group consisting of a transducer, a laser, a speaker, and a filler wire.  
   
   
       5 . The system of  claim 1 , wherein the ultrasonic energy is applied to the liquid metal directly.  
   
   
       6 . The system of  claim 1 , wherein the ultrasonic energy is applied to the solidifying metal interface via the substrate.  
   
   
       7 . The system of  claim 1 , wherein the ultrasonic energy source is applied to the substrate adjacent to a boundary of a liquid metal pool.  
   
   
       8 . The system of  claim 1 , further comprising a table movable in a plane, the table receiving the substrate.  
   
   
       9 . A method of enhancing the quality of deposited metal, comprising: 
 providing a liquid metal on a substrate;    applying ultrasonic energy to solidifying metal in the liquid metal; and    solidifying the liquid metal with reduced grain size.    
   
   
       10 . The method of  claim 9 , wherein the ultrasonic energy is applied to the solid/liquid metal interface.  
   
   
       11 . The method of  claim 9 , wherein the ultrasonic energy is applied to the liquid metal directly.  
   
   
       12 . The method of  claim 9 , wherein applying ultrasonic energy to solidifying metal fractures a dendrite.  
   
   
       13 . The method of  claim 9 , wherein the ultrasonic energy is provided by a source selected from the group consisting of a transducer, a laser, a speaker, and a filler wire.  
   
   
       14 . The method of  claim 9 , wherein the ultrasonic energy is applied to the substrate adjacent a boundary of a liquid metal pool.  
   
   
       15 . The method of  claim 9 , wherein the ultrasonic energy is applied over a range of frequencies.  
   
   
       16 . The method of  claim 15 , wherein the ultrasonic energy is swept through a range of frequencies.  
   
   
       17 . A method of enhancing the quality of deposited metal, comprising: 
 calculating a dendrite arm fracture length;    calculating a resonant frequency applicable for the dendrite arm fracture length;    providing a liquid metal on a substrate; and    applying a tuned ultrasonic energy to solidifying metal in the liquid metal to decrease grain size as the liquid metal solidifies.    
   
   
       18 . The method of  claim 17 , wherein the ultrasonic energy is applied to the solidifying metal via the substrate.  
   
   
       19 . The method of  claim 17 , wherein the ultrasonic energy is applied to the liquid metal directly.  
   
   
       20 . The method of  claim 17 , wherein the ultrasonic energy is applied over a range of frequencies.