Composite sintered body, method of producing the same, and joining material

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.