Abstract: A graphite-copper composite material that contains a copper layer and scaly graphite particles stacked via the copper layer. A volume fraction of copper is from 3 to 30%. A number of intra-particle gaps N obtained by the following (1a) to (1c) is five pieces or less in a stacked cross-sectional surface. (1a) Five measurement visual fields of 930 ?m×1230 ?m are defined in the stacked cross-sectional surface. (1b) The number of gaps having a width of 2 to 5 ?m in the scaly graphite particles is counted in each of the five measurement visual fields, and N1 to N5 are assigned for the five measurement visual fields. (1c) An average value of the number of gaps ((N1+N2+N3+N4+N5)/5) is calculated to obtain the number of intra-particle gaps N.

Abstract: A graphite-copper composite material that includes a copper layer having an average thickness of 15 ?m or less and scaly graphite particles laminated with the copper layer interposed therebetween. The graphite-copper composite material has a copper volume fraction of 3 to 20%. The graphite-copper composite material further has: (A) copper crystal grains of the copper layer having an average grain size of 2.8 ?m or less, a mass fraction of Al of less than 0.02%, and a mass fraction of Si of less than 0.04%, or (B) an interfacial gap of the copper layer and the scaly graphite particles of 150 nm or less.

Abstract: A powder material is put into a cylindrical mold and electrodes are brought into contact with the side surface of the mold and a current is applied to sinter the material in the mold while a pressure is applied to the material. In this process, local temperature difference is kept as small as possible. A pair of electrodes are brought into contact with the side circumferential surface of a cylindrical mold (25) filled with a powder material (28) to which a pressure is applied and a current is applied to the mold (25) to heat the powder material (28) in the mold (25) and a sintered body is obtained. In order to sinter the material by the current application through the pair of electrodes, two pairs of electrodes (19a, 19b, 19c, 19d) which face each other are all brought into contact with the side surface of the mold (25) and the current is supplied through the electrodes (19) alternately.

Abstract: A method of joining a first electroconductive plate member made of metal to a second electroconductive plate member made of metal dissimilar to the metal for the first plate member by the use of at least one anchor peg made of the same metal as the second plate member. The first and second plate members are initially overlapped one above the other to provide a plate assembly which is subsequently clamped under pressure between welding electrodes with the anchor peg positioned between one of the welding electrodes and the first plate member. Thereafter, an electric current is supplied to the welding electrodes to initially cause a portion of the first plate member held in contact with the anchor peg to melt by resistance-heating of the anchor peg to thereby allow the anchor peg to be pierced through the first plate member and then to cause the anchor peg extending completely across a thickness of the first plate member to be welded to the second plate member.