摘要：
A directed-energy deposition process to build a metal article (10), using directed-energy deposition of deposited layers (7) comprising feeding metal feedstock (3) into a focus (2b) of thermal energy (2a) onto an underlying target surface portion (5a) along a tool path, to create a layer (7) of deposited metal material, creating successive layers (7) of deposited metal material by vertically with respect to the deposition plane moving the deposition head (1) on each previous layer (7) of deposited metal material whereby at least one of a first density of the metal feed feedstock and a first specific thermal energy generated by the thermal source provides a specific consistency of each deposited layer and a specific bonding strength thereof to the underlying target surface. The process further comprises providing at least one interface metal layer (9) between an underlying target surface portion (5a) and a successive layer (7) of deposited metal material, by applying a reduced specific energy and an increased density of the metal feedstock (3), so that the metal material of the interface metal layer (9) does at the most only partially fuse with the surface portion (5a) of the substrate (5), to obtain bonding of a reduced strength between the metal interface metal layer (9) and the substrate (5), and to confer to the interface metal layer (9) a higher brittleness, and a decreased bonding to the underlying target surface (5a).
权利要求：
1. An additive manufacturing process to build a metal article (10) according to a digital model, using directed-energy deposition of successively deposited layers (7) of metal material previously molten by action of focused thermal energy (2a) generated by a thermal source (2) selected from high-power lasers, electron arrays and plasma, the process, the process comprising feeding metal feedstock (3) selected from metal powder and metal wire, to a deposition head (1), into a focus (2b) of the thermal energy (2a) onto an underlying target surface portion (5a) of a substrate selected from metal base substrates (5), embedded external elements (11), and an underlying layer (7, 9) of deposited metal material, to melt the feedstock (3) at each moment to create successive pools (8) of molten metal where the molten metal fuses with the underlying target surface portion (5a) along a tool path, to create a layer (7) of deposited metal material, creating successive layers (7) of deposited metal material by moving the deposition head (1) to a vertical distance from each previous layer (7) of deposited metal material and feeding the metal feedstock (3) to the deposition head (1) to create a next layer (7) of deposited metal material, whereby at least one of a first density of the metal feedstock and a first specific thermal energy generated by the thermal source to generate the melting pools is applied, to provide a specific consistency of each deposited layer and a specific bonding strength thereof to the underlying target surface, and further providing at least one interface metal layer (9) between an underlying target surface portion (5a) and a successive layer (7) of deposited metal material, by applying a reduced specific thermal energy generated by the thermal source (2) when generating the interface metal layer (9) from the feedstock (3) and, optionally, an increased density of the metal feedstock (3), to provide thereby at each time successive melting pools (8) in which the metal material of the interface metal layer (9) does at the most only partially fuse with said underlying target surface portion (5a) of said substrate (5), to obtain a bonding having a reduced bonding strength between the metal interface metal layer (9) and the said underlying target surface portion (5a) of said substrate (5), and to confer to the interface metal layer (9) a higher porosity and lack of fusion that results in brittleness than those of the underlying target surface portion (5a) and that of the successive layer (7) of deposited metal material, and a decreased bonding to the underlying target surface portion (5a).
2. The process according to claim 1, wherein the substrate is a metal base substrate (5), such as a metal base plate which supports the layers (7) of deposited metal material successively deposited to build the metal article (10), and wherein the process comprises depositing the at least one interface metal layer (9) on an surface of the metal base substrate (5), by applying a reduced specific thermal energy generated by the thermal source (2) which is lower than said first specific thermal energy and delivering into the focus (2b) of said thermal energy (2a) the metal feedstock (3) at a higher density than said first density of the metal feedstock, to provide successive melting pools (8) in which the metal material for the interface metal layer (9) does not fuse with said surface (5a) of said metal base substrate (5), to obtain welded bonding points having a reduced bonding strength between the interface metal layer (9) and the said surface portion (5a) of said metal base substrate (5), depositing at least one successive layer (7) of deposited metal material on the interface metal layer (9), by again applying the first specific thermal energy generated by the thermal source (2) and the first density of the metal feedstock (3), and wherein the interface metal layer (9) is designed to act as a bottom fracture area for separating the metal article (10) from the metal base substrate (5).
3. The process according to claim 1, wherein the substrate is a metal base substrate (5) such as a metal base plate which supports the layers (7) of deposited metal material which are successively deposited to build the metal article (10), and wherein the process comprises depositing, by applying the first specific thermal energy generated by the thermal source (2) and the first density of the metal feedstock (3), a bottom layer (7) of deposited metal material by providing successive melting pools (8) in which the metal feedstock (3) fuses with the metal base substrate (5); depositing the at least one interface metal layer (9) on the bottom layer (7) of deposited metal material, by applying the reduced specific thermal energy generated by the thermal source (2) and the increased density of the metal feedstock (3) depositing a successive layer (7) of deposited metal material on an uppermost interface metal layer (9), by again applying the first specific thermal energy generated by the thermal source (2) and the first density of the metal feedstock (3) and wherein the interface metal layer (9) is designed to act as a bottom fracture area for separating the metal article (10) from the metal base substrate (5).
4. The process according to claim 1, wherein the substrate is an external element (11) such as a transducer or a fiber, which is to be embedded in the metal article (10), the external element (11) having an upper portion and a lower portion, said lower portion being in contact with the substrate (5) than can be a machined metal component or an additively deposited structure, the target surface (5a) comprising the upper portion of the external element (11), the interface layer (9) deposited surrounding the upper portion and an area of an uppermost successive layer (7) of deposited metal material surrounding the interface layer (9), and wherein the process comprises depositing the at least one interface metal layer (9) on the contour of the upper portion of the external element (11) by providing a higher density of the metal feed feedstock (3) and a reduced specific energy generated by the thermal source and depositing at least a successive layer (7) of deposited metal material by again applying the first specific energy and the first density of the metal feedstock (3), and wherein the interface metal layer (9) is designed to act as a thermal barrier that is partially re-melted by the melt pool generated by the at least one uppermost layer avoiding that the metal pool reaches the external component protecting the external element (11) against heat originating when the successive layers (7) of deposited metal material are generated.
5. The process according to 4, wherein, prior to providing the successive layer (7) of deposited metal material on the interface metal layer (9), the interface metal layer (9) is refused by means of the deposition head (1) passing over the interface metal layer (9) applying a refusing heat without feeding metal feedstock (3).
6. The process according to claim 1, wherein the metal article (10) comprises a support structure (12) for the metal article (10) as a portion of the metal article (10) built according to the digital model, and wherein the process comprises building the support structure (12) by providing a plurality of successive interface metal layers (9) according to a pattern provided in the digital model of the metal article (10), so that fracture areas in the metal article (10) are created where the interface metal layers (9) are in contact with the successive layers (7) of deposited metal material.
7. The process according to claim 6 comprising depositing the at least one bottom interface metal layer (7) on a surface of the metal base substrate (5) on which the metal article (10) is built, and wherein the bottom interface metal layer (9) is designed to act as a bottom fracture area for separating the metal article (10) from the metal base substrate (5).
8. The process according to any of claims 1 to 7, wherein the metal feedstock (3) is metal powder.
9. The process according to any of claims 1 to 7, wherein the metal feedstock (3) is metal wire.
10. The process according to any of claims 1 to 9, wherein the reduced specific energy applied to generate the interface metal layer (9) is in an energy range of 20% to 40% of the first specific energy provided to generate the layer of deposited metal material.
11. The process according to any of claims 1 to 10, wherein the reduced specific energy applied to generate the interface metal layer (9) is in an energy range of 25% to 35% of the first specific energy provided to generate the layer of deposited metal material.
12. The process according to any of claims 1 to 11, wherein the increased density provided to the metal feedstock (3) when generating the interface metal layer (9) is within a density range of 50% to 250% higher than the first density of the feedstock (3) provided to generate the layer (7) of deposited metal material.
13. The process according to any of claims 1 to 12, wherein the increased density provided to the metal feedstock (3) when generating the interface metal layer (9) is within a density range of 100% to 200% higher than the first density of the feedstock (3) provided to generate the layer (7) of deposited metal material.
14. The process according to any of claims 1 to 13 wherein a laser with a power greater than 1 KW is used.