WE CLAIM
1. A method of making a component (C), comprising:
depositing a metallic powder (P) on a workplane (128);
directing a beam from a directed energy source (124) to fuse the powder
(P) in a pattern corresponding to a cross-sectional layer of the component (C);
repeating in a cycle the steps of depositing and fusing to build up the
component (C) in a layer-by layer fashion; and
during the cycle of depositing and melting, using an external heat control
apparatus (144, 146, 150, 154) separate from the directed energy source (124) to
maintain a predetermined temperature profile of the component (C), such that the
resulting component (C) has a directionally-solidified or single-crystal
microstructure.
2. The method of claim 1 wherein the powder (P) and component (C) are
supported on a build platform (120) which is moveable along a vertical axis.
3. The method of claim 2 further comprising lowering the build platform
(120) after each step of fusing the powder (P) by a selected layer increment.
4. The method of claim 1 wherein the external heat control apparatus (144)
comprises a layer of thermal insulation (144) surrounding the component (C).
5. The method of claim 1 wherein the external heat control apparatus (146)
comprises a heater (146) surrounding the component (C).
6. The method of claim 1 wherein the external heat control apparatus (150)
comprises a quartz lamp (150) positioned near the component (C).
7. The method of claim 1 wherein the external heat control apparatus (154)
comprises at least one induction coil (154) surrounding the component (C).
8. The method of claim 1 wherein the external heat control apparatus (144,
146, 150, 154) is used to maintain the component (C) at a solutioning temperature.
9. The method of claim 1 wherein the external heat control apparatus (144,
146, 150, 154) is used to control both the temperature and the heating rate of the
component (C) during the of depositing and fusing.
10. An apparatus for making a metallic component (C), comprising:
a build enclosure (122) configured to hold metallic powder (P) of a
predetermined composition;
a directed energy source (124) operable to produce an energy beam (B)
suitable for fusing the metallic powder (P);
a beam steering apparatus (126) operable to direct the energy beam (B)
over the metallic powder (P) in a pattern corresponding to a cross-sectional layer
of the component (C); and
an external heat control apparatus (144, 146, 150, 154) separate from the
directed energy source (124) operable to maintain a predetermined temperature
profile within the build enclosure (122).
11. The apparatus (144, 146, 150, 154) of claim 10 further including a
build platform (120) disposed inside the build enclosure (122), the build platform
(120) being moveable along a vertical axis.
12. The apparatus of claim 10 wherein the external heat control apparatus
(144) comprises a layer of thermal insulation (144) surrounding the component
(C).
13. The apparatus of claim 10 wherein the external heat control apparatus
(146) comprises a heater (146) surrounding the component (C).
14. The apparatus of claim 10 wherein the external heat control apparatus
(144, 146, 150, 154) comprises a quartz lamp positioned near the component (C).
15. The apparatus of claim 10 wherein the external heat control apparatus
(144, 146, 150, 154) comprises at least one induction coil surrounding the build
enclosure.
16. The apparatus of claim 15 wherein an induction coil (156') is mounted
above the build enclosure (122).
17. The apparatus of claim 16 wherein the induction coil (154') is mounted
above the build enclosure (122) by an arm (159) connected to an actuator (161),
wherein the actuator (161) is operable to move the induction coil (156') between
an in-use position and a retracted position away from the build enclosure (122).