Blended powder solid-supersolidus liquid phase sintering

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.

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.

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.

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.

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.