Layered manufacturing of single crystal alloy components

Abstract

A method of making a component includes: depositing a metallic powder on a workplane; directing a beam from a directed energy source to fuse the powder in a pattern corresponding to a cross-sectional layer of the component; repeating in a cycle the steps of depositing and fusing to build up the component in a layer-by layer fashion; and during the cycle of depositing and melting, using an external heat control apparatus separate from the directed energy source to maintain a predetermined temperature profile of the component, such that the resulting component has a directionally-solidified or single-crystal microstructure.

What is claimed is: 
     
         1 . A method of making a component, comprising:
 depositing a metallic powder on a workplane;   directing a beam from a directed energy source to fuse the powder in a pattern corresponding to a cross-sectional layer of the component;   repeating in a cycle the steps of depositing and fusing to build up the component in a layer-by layer fashion;   during the cycle of depositing and melting, using an external heat control apparatus separate from the directed energy source, wherein the external heat control apparatus controls both the temperature and the heating rate of the component during the cycle of depositing and fusing to maintain a predetermined temperature profile of the component; and   using a retractable induction heater comprising an induction coil connected to an electric power source to directly control remelt and solidification of the component by:
 moving the retractable induction heater during the cycle of depositing and melting into an extended position over the workplane and activating to heat an exposed layer of the component, and 
 after completion of the desired heating cycle, moving the retractable induction heater to a retracted position away from the workplane so that a next layer of powder can be applied on the workplane. 
   
     
     
         2 . The method of  claim 1  wherein the directed energy source is used to continuously remelt the exposed layer until the retractable induction heater can be moved into the extended position. 
     
     
         3 . The method of  claim 1  wherein the powder and component are supported on a build platform which is moveable along a vertical axis. 
     
     
         4 . The method of  claim 2  further comprising lowering the build platform after each step of fusing the powder by a selected layer increment. 
     
     
         5 . The method of  claim 1  wherein the external heat control apparatus comprises a layer of thermal insulation surrounding the component. 
     
     
         6 . The method of  claim 1  wherein the external heat control apparatus comprises a heater surrounding the component. 
     
     
         7 . The method of  claim 1  wherein the external heat control apparatus comprises a quartz lamp positioned near the component. 
     
     
         8 . The method of  claim 1  wherein the external heat control apparatus comprises at least one induction coil surrounding the component. 
     
     
         9 . The method of  claim 1  wherein the external heat control apparatus is used to maintain the component at a solutioning temperature. 
     
     
         10 . The method of  claim 1 , wherein the retractable induction heater is positioned over a build platform and above the workplane by an arm connected to an actuator, and wherein moving the induction heater between the extended and retracted positions is performed using the actuator. 
     
     
         11 . The method of  claim 1 , wherein the external heat control apparatus comprises an induction heater including one or more individual induction coils surrounding a build platform and connected to an electric power source, and wherein the induction coils of the retractable induction heater are positioned over the build platform and above the workplane.