Composite sintered body, method of producing the same, and joining material
A first pre-sintered body composed of a powder made of a first Ni-based alloy is prepared, and a second pre-sintered body composed of a powder made of a second Ni-based alloy is prepared. Subsequently, the first and second pre-sintered bodies are positioned to face each other across a predetermined gap, and a joining material made of a Ni-based alloy having a lower liquidus temperature than the first and second Ni-based alloys is placed in a space that adjoins the first and second pre-sintered bodies and to which the gap opens. After the placing of the joining material, the first and second pre-sintered bodies are heated to melt the joining material, fill the gap with the molten joining material, and subsequently turn the first and second pre-sintered bodies into first and second sintered bodies, respectively.
1 . A method for producing a composite sintered body, comprising:
preparing a first pre-sintered body composed of a powder made of a first Ni-based alloy;
preparing a second pre-sintered body composed of a powder made of a second Ni-based alloy;
positioning the first and second pre-sintered bodies such that the first and second pre-sintered bodies face each other across a predetermined gap;
placing a joining material in a space that adjoins the first and second pre-sintered bodies and to which the gap opens, the joining material being made of a Ni-based alloy having a lower liquidus temperature than the first and second Ni-based alloys; and
after the placing of the joining material, heating the first and second pre-sintered bodies to melt the joining material, fill the gap with the molten joining material, and subsequently turn the first and second pre-sintered bodies into first and second sintered bodies, respectively.
2 . The method according to claim 1 , wherein
a first unsintered body is fabricated by shaping the powder made of the first Ni-based alloy into a predetermined shape,
a second unsintered body is fabricated by shaping the powder made of the second Ni-based alloy into a predetermined shape,
the first and second unsintered bodies are positioned to face each other across the gap,
the joining material is placed in a space that adjoins the first and second unsintered bodies and to which the gap opens, and
in a state where the joining material is placed in the space, the first and second unsintered bodies are heated at a temperature lower than the liquidus temperature of the joining material to turn the first and second unsintered bodies into the first and second pre-sintered bodies, respectively.
3 . A method for producing a composite sintered body, comprising:
preparing a first pre-sintered body composed of a powder made of a first Ni-based alloy;
preparing a second pre-sintered body composed of a powder made of a second Ni-based alloy;
positioning the first and second pre-sintered bodies such that the first and second pre-sintered bodies face each other, with a joining material interposed between the first and second pre-sintered bodies, the joining material being made of a Ni-based alloy having a lower liquidus temperature than the first and second Ni-based alloys; and
heating the first and second pre-sintered bodies to melt the joining material and subsequently turn the first and second pre-sintered bodies into first and second sintered bodies, respectively.
4 . The method according to claim 3 , wherein
a first unsintered body is fabricated by shaping the powder made of the first Ni-based alloy into a predetermined shape,
a second unsintered body is fabricated by shaping the powder made of the second Ni-based alloy into a predetermined shape,
the first and second unsintered bodies are positioned to face each other, with the joining material interposed between the first and second unsintered bodies, and
in a state where the joining material is interposed between the first and second unsintered bodies, the first and second unsintered bodies are heated at a temperature lower than the liquidus temperature of the joining material to turn the first and second unsintered bodies into the first and second pre-sintered bodies, respectively.
5 . The method according to claim 2 , wherein the first and second unsintered bodies are fabricated by metal injection molding.
6 . The method according to claim 1 , wherein the first and second Ni-based alloys have the same composition.
7 . The method according to claim 1 , wherein each of the first and second Ni-based alloys contains, in percent by mass, 18.0 to 25.0% Cr, 7.0 to 11.0% Mo, 22.0% or less Fe, 4.5% or less Nb+Ta, and 3.0% or less Co.
8 . The method according to claim 1 , wherein the Ni-based alloy constituting the joining material contains, in percent by mass, 18.0 to 23.0% Cr, 1.5 to 6.5% Mo, 3.5 to 8.5% Si, 13.0% or less Fe, 2.5% or less Nb+Ta, and 1.0% or less Co.
9 . The method according to claim 1 , wherein the joining material is a mixture of a first powder made of a third Ni-based alloy having a lower liquidus temperature than the first and second Ni-based alloys and a second powder made of the first or second Ni-based alloy.
10 . The method according to claim 9 , wherein a mixing ratio of the first powder to the second powder is from 40%:60% to 80%:20% in percent by mass.
11 . The method according to claim 9 , wherein the third Ni-based alloy contains, in percent by mass, 16.0 to 22.0% Cr and 8.0 to 12.0% Si.