| 摘要 |
1,265,343. Powder metallurgy. INTERNATIONAL NICKEL Ltd. Feb.21, 1969 [March 1, 1968], No.9567/69. Heading C7D. Wrought homogeneous composite powder containing at least 15% volume of a compressively deformable metal is made by dry impact milling the powder mixture below the recrystallization temperature of the deformable metal until the metal particles are reduced to less than half their original thickness and the composite particles are work hardened to at least the mean of the base and saturation hardness of the composite. Milling is preferably effected in a ball mill, vibrator mill, shaker mill, planetory mill or stirred attritor ball mill in which the volume ratio balls: powder > 10 e.g. 12:1 to 50:1. The ball diameter is at least 50 times, preferably 250 times the powder size and the milling energy input is such as to give the required hardness in 24 hours or less. The ball mill may have a cooling jacket to keep the temperature below 65‹ C. and milling may be effected in an atmosphere of air, N 2 , H 2 , Co 2 , A or He. The original metal powder size may be up to 1000Á, preferably 3-200Á. Refractory borides, carbides, oxides and nitrides < 2Á size may be added to the metal powder e.g. those of Th, Zn, Hf, Ti and also the oxides of Si, Al, Y, Ce, U, Mg, Ca, Be. Alloys, super alloys, dispensionhardened alloys, cemented WC-Co, and cement powders may be formed as well as particles of a metal which reacts with a less stable metal oxide to form a stable dispersed oxide phase in a metal matrix. The uniform composite particle size may be up to 500Á e.g. 20-200Á and they are compacted e.g. pressed, rolled or extruded, and sintered. Simple alloys based on Pb, Zn, Al, Mg, Cu, Ni, Co, Fe, Cr, Mo or W, heat resistant alloys based on Ni-Cr, Co-Cr, Fe-Cr with additions such as Mo, W, Nb, Ta, Al, Ti, Zr may be produced. A large number of examples are included such as Ni-Tho 2 ; stainless steel; tool steel 20W, 4Cr, 2V, 0À8C; managing steel 18À5Ni, 7À5 Co, 4À8 Mo 0À1 Al, 0À4 Ti, 0À03 max. C; 80 Fe-20 Cu; 50Cu-50Pb; Fe-15Al; 60Ni, 20W, 20vol % ZrO 2 ; Pb or Fe with 1-95 Cu; W with 5-98 Cu or 2-98 Ag; Cr with 5-95 Cu. |
