| 摘要 |
PURPOSE:To permit diffusion bonding with high strength and reliability without generating cracking by interposing Ni or an Ni alloy having a coefft. of thermal expansion resembling to that of a sintered hard alloy and a limited thickness or below as an insert metal between the sintered hard alloy and steel. CONSTITUTION:An insert metal 2 of Ni or an Ni alloy of >=50mum thickness is interposed and combined between a cutting tip 1 of a sintered hard alloy and a stem part 3 of tool steel and while the assembly is held in such a way as not to be disassembled to each piece, the assembly is inserted into a diffusion bonding furnace (not shown) and is subjected to diffusion bonding for about 10-180min at about 950-1,100 deg.C bonding temp. and about 0.5-5.0kg/cm<2> bonding pressure under about 10<-4>torr reduced pressure, whereby the tip 1 and the part 3 are bound to one body through the metal 2, and a cutting tool is obtained. The generation of cracking in the stage of cooling after the bonding is prevented by defining the coeffts. of thermal expansion of the above-mentioned alloy 1, steel 3 and metal 2 as alphaS, alphaK, alphaI respectively and selecting the coeffts. at alphaK>alphaI>=alphaS. |
