Processing of Ni/Al Intermetallic and its Composites Using Particle Coating Route

摘要

In this article, aluminum powder was coated with nickel in atomic ratio of 1:1 by two coating methods, either electrolytic or electroless deposition. Alumina short fibers of Saffile type and SiC powders were also coated with nickel using both coating methods. More details will be given for both coating methods. Ni-coated aluminum powders were divided into four portions, the first one was heat treated at 550℃ in pure hydrogen for 30 min., cold pressed at 600 MPa then sintered at 1000℃. The second portion was directly cold pressed, and sintered at the same conditions. The third and fourth portions were mixed with 10 wt% Ni-coated alumina and 10wt% Ni-coated SiC, cold pressed and sintered, respectively. Ni/Al intermetallic was formed by heating the Ni-coated aluminum powders at 550℃ for 30 min. The compressibility of Ni/Al intermetallic powders (the first portion) was lower than that of the as received Ni-coated aluminum powders. After sintering, the compacts made from the 2nd portion showed high relative density of 98% compared with that of 1st portion which showed relative density of 81%. Moreover, alumina or SiC reinforced Ni/Al intermetallic exhibited good compressibility, higher hardness and good distribution of reinforcements.