Apparatus and method for direct writing of single crystal super alloys and metals

Abstract

Apparatus and methods for direct writing of single crystal super alloys and metals are provided. In one method, a substrate is heated to a pretermined temperature below its melting point, and a laser is used to form a melt pool on a surface of a substrate. The substrate is positioned on a base plate, and the laser and the base plate are movable relative to each other, with the laser being used for direct metal deposition and the substrate is heated to a temperature below its melting point. A superalloy powder is introduced to the melt pool, and the temperature of the melt pool is controlled to maintain a predetermined thermal gradient on a solid and liquid interface of the melt pool so as to form a single crystal deposit on the substrate.

What is claimed is: 
     
         1 . A method for direct writing of single crystal super alloys and metals, the method comprising:
 heating a substrate to a predetermined temperature below its melting point;   using a laser to form a melt pool on a surface of the substrate, wherein the substrate is positioned on a base plate, and wherein the laser and the base plate are movable relative to each other, the laser being used for direct metal deposition;   introducing a superalloy powder to the melt pool; and   controlling the temperature of the melt pool to maintain a predetermined thermal gradient on a solid and liquid interface of the melt pool so as to form a single crystal deposit on the substrate.   
     
     
         2 . The method of  claim 1 , wherein the laser has a variable power source, and wherein controlling the temperature of the melt pool comprises:
 adjusting the variable power source of the laser.   
     
     
         3 . The method of  claim 1 , wherein the laser has a variable power output controllable by a laser power controller, and wherein controlling the temperature of the melt pool comprises:
 measuring the temperature of the melt pool;   receiving the temperature measured at a controller;   comparing the temperature measured to a reference temperature; and   adjusting the variable power output of the laser.   
     
     
         4 . The method of  claim 3 , wherein the temperature measured is lower than the reference temperature, and wherein adjusting the variable power output of the laser comprises:
 increasing the variable power output of the laser.   
     
     
         5 . The method of  claim 4 , wherein increasing the variable power output of the laser comprises:
 increasing the voltage supplied by the laser power controller.   
     
     
         6 . The method of  claim 3 , wherein the temperature measured is higher than the reference temperature, and wherein adjusting the variable power output of the laser comprises:
 decreasing the variable power output of the laser.   
     
     
         7 . The method of  claim 6 , wherein decreasing the variable power output of the laser comprises:
 decreasing the voltage supplied by the laser power controller.   
     
     
         8 . The method of  claim 1 , wherein the laser and the base plate are movable in 3 directions with respect to each other. 
     
     
         9 . The method of  claim 1 , further comprising:
 moving the laser in a horizontal plane with respect to the substrate.   
     
     
         10 . The method of  claim 1 , further comprising:
 moving the base plate in a vertical direction with respect to the laser.   
     
     
         11 . An apparatus for direct writing of single crystal super alloys and metals comprising:
 a laser having a power output;   a base plate configured for holding a substrate thereon;   a DMD head configured to supply a stream of superalloy powder onto the substrate;   an induction heating source positioned to heat the substrate on the base plate to a predetermined temperature; and   a controller for controlling the power output of the laser to maintain the predetermined temperature, wherein the controller is responsive to a measured temperature of at least one of a melt pool on the substrate and the superalloy powder.   
     
     
         12 . The apparatus of  claim 11 , further comprising:
 a pyrometer configured to measure the temperature of the at least one of the melt pool on the substrate and the superalloy powder.   
     
     
         13 . The apparatus of  claim 12 , wherein the pyrometer is in communication with the controller. 
     
     
         14 . The apparatus of  claim 13 , wherein the laser has a variable power output controlled by a laser power controller. 
     
     
         15 . The apparatus of  claim 14 , wherein the laser power controller is in communication with the controller. 
     
     
         16 . The apparatus of  claim 11 , wherein the laser passes through the DMD head onto the substrate to form a melt pool. 
     
     
         17 . The apparatus of  claim 11 , wherein the laser and the base plate are movable in 3 directions with respect to each other. 
     
     
         18 . The apparatus of  claim 11 , wherein the laser is movable in a horizontal plane with respect to the substrate. 
     
     
         19 . The apparatus of  claim 11 , wherein the base plate is movable in a vertical direction with respect to the laser.