# US 7,070,734 B2 · Blended powder solid-supersolidus liquid phase sintering > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,070,734 B2 - Document ID: US7070734B2 - Status: Granted - Kind: B2 - Application number: 10/801,970 - Filed: 2004-03-16 - Published: 2006-04-20 - Granted: 2006-07-04 - Earliest claimed: 2002-07-12 - Assignees: The Ex One Company - Inventors: Jianxin Liu; Michael L. Ryneson - Web page: https://patentgrep.com/patent/US7070734B2 ## CPC - B22F 1/052: characterised by a mixture of particles of different sizes or by the particle size distribution - B22F 1/09: {Mixtures of metallic powders} - B33Y 70/00: Materials specially adapted for additive manufacturing - B22F 2998/00: Supplementary information concerning processes or compositions relating to powder metallurgy - B33Y 80/00: Products made by additive manufacturing - Y02P 10/25: Process efficiency - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A green article comprising an A-B powder mixture and methods of manufacturing such green articles and corresponding sintered articles are disclosed. The A-B powder mixture consists of a minor volume fraction of a relatively fine powder A and a complementary major volume fraction of a relatively coarse prealloyed powder B wherein the A-B powder mean particle size ratio is at least about 1:5. Metal powder A consists of one or more elemental metals or alloys which has a melting or solidus temperature above the highest sintering temperature at which the A-B powder mixture may be sintered without slumping. Prealloyed metal powder B consists of one or more alloys which are amenable to supersolidus liquid phase sintering. Green articles made from the A-B powder have a wider sintering temperature window than do articles made from prealloyed metal powder B alone. ## Claims ### Claim 1 A method of producing a green article having an enhanced sintering temperature window, said method comprising the steps of: a) mixing together a minor volume fraction of a relatively fine metal powder and a complementary major volume fraction of a relatively coarse prealloyed metal powder to produce a metal powder mixture; and b) forming a green article from said metal powder mixture; wherein the relatively fine metal is essentially solid at the highest sintering temperature at which the green article can be sintered without slumping, the relatively coarse prealloyed metal powder is amenable to supersolidus liquid phase sintering, and the ratio of the mean particle size of the relatively fine metal powder to the mean particle size of the relatively coarse prealloyed metal powder is at least about 1:5. ### Claim 2 (depends on 1) The method of claim 1, wherein said step of forming a green article further comprises powder containerization. ### Claim 3 (depends on 1) The method of claim 1, wherein said step of forming a green article further comprises a free-forming layer-wise buildup technique. ### Claim 4 (depends on 3) The method of claim 3, wherein the free-forming layer-wise buildup technique is three-dimensional printing. ### Claim 5 (depends on 3) The method of claim 3, wherein the free-forming layer-wise buildup technique is selective laser sintering. ### Claim 6 (depends on 1) The method of claim 1, wherein said step of forming a green article further comprises metal injection molding. ### Claim 7 (depends on 1) The method of claim 1, wherein said step of forming a green article further comprises die pressing. ### Claim 8 (depends on 1) The method of claim 1, further comprising the step of providing the relatively fine metal powder, wherein the relatively fine metal powder consists of more than one elemental metal or metal alloy, each of said elemental metals or metal alloys being essentially solid at the highest sintering temperature at which the green article can be sintered without slumping. ### Claim 9 (depends on 1) The method of claim 1, further comprising the step of providing the relatively coarse prealloyed metal powder, wherein the relatively coarse prealloyed metal powder consists of more than one metal alloy, each of said metal alloys being amenable to supersolidus liquid phase sintering. ### Claim 10 A method of producing a green article having an enhanced sintering temperature window, said method comprising the steps of: a) mixing together a minor volume fraction of a relatively fine metal powder and a complementary major volume fraction of a relatively coarse prealloyed metal powder to produce a metal powder mixture; and b) forming a green article from said metal powder mixture; wherein said minor volume fraction of a relatively fine metal powder consists of at least two sub-fractions of successively finer mean particle size, each of said successive sub-fractions consists of metal powder that is essentially solid at the highest sintering temperature at which the green article can be sintered without slumping, the relatively coarse prealloyed metal powder is amenable to supersolidus liquid phase sintering, the ratio of the mean particle size of the coarsest of said successive sub-fractions to the mean particle size of the relatively coarse prealloyed metal powder is at least about 1:5, and the ratio of the mean particle size of each finer successive sub-fraction to the mean particle size of an immediately preceding coarser successive sub-fraction is at least about 1:5. ### Claim 11 (depends on 10) The method of claim 10, wherein said step of forming a green article further comprises powder containerization. ### Claim 12 (depends on 10) The method of claim 10, wherein said step of forming a green article further comprises a free-forming layer-wise buildup technique. ### Claim 13 (depends on 12) The method of claim 12, wherein the free-forming layer-wise buildup technique is three-dimensional printing. ### Claim 14 (depends on 12) The method of claim 12, wherein the free-forming layer-wise buildup technique is selective laser sintering. ### Claim 15 (depends on 10) The method of claim 10, wherein said step of forming a green article further comprises metal injection molding. ### Claim 16 (depends on 10) The method of claim 10, wherein said step of forming a green article further comprises die pressing. ### Claim 17 (depends on 10) The method of claim 10, further comprising the step of providing the relatively fine metal powder, wherein at least one of the successive sub-fractions consists of two or more elemental metals or metal alloys, each of said elemental metals or metal alloys being essentially solid at the highest sintering temperature at which the green article can be sintered without slumping. ### Claim 18 (depends on 10) The method of claim 10, further comprising the step of providing the relatively coarse prealloyed metal powder, wherein the relatively coarse prealloyed metal powder consists of more than one metal alloy, each of said metal alloys being amenable to supersolidus liquid phase sintering. ### Claim 19 A method of densifying a green article, said method comprising the steps of: a) mixing together a minor volume fraction of a relatively fine metal powder and complementary major volume fraction of a relatively coarse prealloyed metal powder to produce a metal powder mixture; b) forming a green article from said metal powder mixture; c) heating the green article to a sintering temperature that is below the liquidus temperature of the relatively coarse prealloyed metal powder; and d) holding the green article at said sintering temperature for a time of sufficiently long duration to densify the green article; wherein the relatively fine metal powder is essentially solid at the highest sintering temperature at which the green article can be sintered without slumping, the relatively coarse prealloyed metal powder is amenable to supersolidus liquid phase sintering, and the ratio of the mean particle size of the relatively fine metal powder to the mean particle size of the relatively coarse prealloyed metal powder is at least about 1:5. ### Claim 20 (depends on 19) The method of claim 19, wherein the step of heating the green article to a sintering temperature comprises heating the green article to a sintering temperature that is below the solidus temperature of the relatively coarse prealloyed metal powder. ### Claim 21 (depends on 19) The method of claim 19, wherein the step of heating the green article to a sintering temperature comprises heating the green article to a sintering temperature that is between the solidus temperature and the liquidus temperature of the relatively coarse prealloyed metal powder. ### Claim 22 (depends on 19) The method of claim 19, further comprising the step of providing the relatively coarse prealloyed metal powder, wherein the relatively coarse prealloyed metal powder consists of more than one metal alloy and each of said metal alloys is amenable to supersolidus liquid phase sintering, and said step of heating the green article to a sintering temperature comprises heating the green article to a sintering temperature that is lower than the liquidus temperature of each of the relatively coarse prealloyed metal powder metal alloys. ### Claim 23 (depends on 22) The method of claim 22, wherein said step of heating the green article to a sintering temperature comprises heating the green article to a sintering temperature that is lower than the solidus temperature of each of the relatively coarse prealloyed metal powder metal alloys. ### Claim 24 (depends on 22) The method of claim 22, wherein said step of heating the green article to a sintering temperature comprises heating the green article to a sintering temperature that exceeds the solidus temperature of each of the relatively coarse prealloyed metal powder metal alloys. ### Claim 25 (depends on 19) The method of claim 19, further comprising the step of providing the relatively fine metal powder, wherein the relatively fine metal powder consists of more than one elemental metal or metal alloy, each of said elemental metals or metal alloys being essentially solid at the highest sintering temperature at which the green article can be sintered without slumping. ### Claim 26 (depends on 19) The method of claim 19, wherein said step of forming a green article further comprises powder containerization. ### Claim 27 (depends on 19) The method of claim 19, wherein said step of forming a green article further comprises a free-forming layer-wise buildup technique. ### Claim 28 (depends on 27) The method of claim 27, wherein the free-forming layer-wise buildup technique is three-dimensional printing. ### Claim 29 (depends on 27) The method of claim 27, wherein the free-forming layer-wise buildup technique is selective laser sintering. ### Claim 30 (depends on 19) The method of claim 19, wherein said step of forming a green article further comprises metal injection molding. ### Claim 31 (depends on 19) The method of claim 19, wherein said step of forming a green article further comprises die pressing. ### Claim 32 A method of densifying a green article, said method comprising the steps of: a) mixing together a minor volume fraction of a relatively fine metal powder and complementary major volume fraction of a relatively coarse prealloyed metal powder to produce a metal powder mixture; b) forming a green article from said metal powder mixture; c) heating the green article to a sintering temperature that is below the liquidus temperature of the relatively coarse prealloyed metal powder; and d) holding the green article at said sintering temperature for a time of sufficiently long duration to densify the green article; wherein said minor volume fraction of a relatively fine metal powder consists of at least two sub-fractions of successively finer mean particle size, each of said successive sub-fractions consists of metal powder that is essentially solid at the highest sintering temperature at which the green article can be sintered without slumping, the relatively coarse prealloyed metal powder is amenable to supersolidus liquid phase sintering, the ratio of the mean particle size of the coarsest of said successive sub-fractions to the mean particle size of the relatively coarse prealloyed metal powder is at least about 1:5, and the ratio of the mean particle size of each finer successive sub-fraction to the mean particle size of an immediately preceding coarser successive sub-fraction is at least about 1:5. ### Claim 33 (depends on 32) The method of claim 32, wherein the step of heating the green article to a sintering temperature comprises heating the green article to a sintering temperature that is below the solidus temperature of the relatively coarse prealloyed metal powder. ### Claim 34 (depends on 32) The method of claim 32, wherein the step of heating the green article to a sintering temperature comprises heating the article to a sintering temperature that is between the solidus temperature and the liquidus temperature of the relatively coarse prealloyed metal powder. ### Claim 35 (depends on 32) The method of claim 32, further comprising the step of providing the relatively coarse prealloyed metal powder, wherein the relatively coarse prealloyed metal powder consists of more than one metal alloy and each of said metal alloys is amenable to supersolidus liquid phase sintering, and said step of heating the green article to a sintering temperature comprises heating the green article to a sintering temperature that is lower than the liquidus temperature of each of the relatively coarse prealloyed metal powder metal alloys. ### Claim 36 (depends on 35) The method of claim 35, wherein said step of heating the green article to a sintering temperature comprises heating the green article to a sintering temperature that is lower than the solidus temperature of each of the relatively coarse prealloyed metal powder metal alloys. ### Claim 37 (depends on 35) The method of claim 35, wherein said step of heating the green article to a sintering temperature comprises heating the green article to a sintering temperature that exceeds the solidus temperature of each of the relatively coarse prealloyed metal powder metal alloys. ### Claim 38 (depends on 32) The method of claim 32, further comprising the step of providing the relatively fine metal powder, wherein at least one of the successive sub-fractions consists of two or more elemental metals or metal alloys, each of said elemental metals or metal alloys being essentially solid at the highest sintering temperature at which the green article can be sintered without slumping. ### Claim 39 (depends on 32) The method of claim 32, wherein said step of forming a green article further comprises powder containerization. ### Claim 40 (depends on 32) The method of claim 32, wherein said step of forming a green article further comprises a free-forming layer-wise buildup technique. ### Claim 41 (depends on 40) The method of claim 40, wherein the free-forming layer-wise buildup technique is three-dimensional printing. ### Claim 42 (depends on 40) The method of claim 40, wherein the free-forming layer-wise buildup technique is selective laser sintering. ### Claim 43 (depends on 32) The method of claim 32, wherein said step of forming a green article further comprises metal injection molding. ### Claim 44 (depends on 32) The method of claim 32, wherein said step of forming a green article further comprises die pressing. ### Claim 45 A method of layer-wise free-forming a green article, said method comprising the steps of: a) mixing together a minor volume fraction of a relatively fine metal powder and a complementary major volume fraction of a relatively coarse prealloyed metal powder to produce a metal powder mixture; and b) selectively binding together metal powder particles of the metal powder mixture within each metal powder layer of a sequentially applied series of metal powder layers to form the green article; wherein step a) is performed prior to step b), the relatively fine metal is essentially solid at the highest sintering temperature at which the green article can be sintered without slumping, the relatively coarse prealloyed metal powder is amenable to supersolidus liquid phase sintering, and the ratio of the mean particle size of the relatively fine metal powder to the mean particle size of the relatively coarse prealloyed metal powder is at least about 1:5. ### Claim 46 (depends on 45) The method of claim 45, wherein the step of selectively binding together metal powder particles includes selectively jet-spraying a fugitive binder onto the metal powder particles. ### Claim 47 (depends on 45) The method of claim 45, wherein the step of selectively binding together metal powder particles includes selectively scanning the metal powder particles with a laser beam. ### Claim 48 (depends on 45) The method of claim 45, further comprising the step of providing the relatively fine metal powder, wherein the relatively fine metal powder consists of more than one elemental metal or metal alloy, each of said elemental metals or metal alloys being essentially solid at the highest sintering temperature at which the green article can be sintered without slumping. ### Claim 49 (depends on 45) The method of claim 45, further comprising the step of providing the relatively coarse prealloyed metal powder, wherein the relatively coarse prealloyed metal powder consists of more than one metal alloy, each of said metal alloys being amenable to supersolidus liquid phase sintering. ### Claim 50 (depends on 45) The method of claim 45, wherein the step of selectively binding together metal powder particles includes using a mask to selectively expose the metal powder particles to light. ### Claim 51 (depends on 50) The method of claim 50, wherein the step of mixing includes making a slurry of the metal powder mixture and a volatile liquid, and wherein at least one metal layer of said sequentially applied series of metal powder layers is applied in the form of said slurry. ### Claim 52 A method of layer-wise free-forming a green article, said method comprising the steps of: a) mixing together a minor volume fraction of a relatively fine metal powder and a complementary major volume fraction of a relatively coarse prealloyed metal powder to produce a metal powder mixture; and b) selectively binding together metal powder particles of the metal powder mixture within each metal powder layer of a sequentially applied series of metal powder layers to form the green article; wherein step a) is performed prior to step b), said minor volume fraction of a relatively fine metal powder consists of at least two sub-fractions of successively finer mean particle size, each of said successive sub-fractions consists of metal powder that is essentially solid at the highest sintering temperature at which the green article can be sintered without slumping, the relatively coarse prealloyed metal powder is amenable to supersolidus liquid phase sintering, the ratio of the mean particle size of the coarsest of said successive sub-fractions to the mean particle size of the relatively coarse prealloyed metal powder is at least about 1:5, and the ratio of the mean particle size of each finer successive sub-fraction to the mean particle size of an immediately preceding coarser successive sub-fraction is at least about 1:5. ### Claim 53 (depends on 52) The method of claim 52, wherein the step of selectively binding together metal powder particles includes selectively jet-spraying a fugitive binder onto the metal powder particles. ### Claim 54 (depends on 52) The method of claim 52, wherein the step of selectively binding together metal powder particles includes selectively scanning the metal powder particles with a laser beam. ### Claim 55 (depends on 52) The method of claim 52, further comprising the step of providing the relatively fine metal powder, wherein at least one of the successive sub-fractions consists of two or more elemental metals or metal alloys, each of said elemental metals or metal alloys being essentially solid at the highest sintering temperature at which the green article can be sintered without slumping. ### Claim 56 (depends on 52) The method of claim 52, further comprising the step of providing the relatively coarse prealloyed metal powder, wherein the relatively coarse prealloyed metal powder consists of more than one metal alloy, each of said metal alloys being amenable to supersolidus liquid phase sintering. ### Claim 57 (depends on 52) The method of claim 52, wherein the step of selectively binding together metal powder particles includes using a mask to selectively expose the metal powder particles to light. ### Claim 58 (depends on 57) The method of claim 57, wherein the step of mixing includes making a slurry of the metal powder mixture and a volatile liquid, and wherein at least one metal layer of said sequentially applied series of metal powder layers is applied in the form of said slurry.