Abstract
The relative density of the H2 gas-sintered compact (Ds) from Cu-10.8 mass%Sn or Cu-10.8 mass%Ni alloy fine powder of 5-15 μm in grain size and the effect of the addition of iron powder on Ds were investigated, compared with the previous result on Cu fine powder.
The results obtained were as follows: (1) The Ds of both alloy sintered compacts did not reach 100%, irrespective of the fabrication condition, as in the case of the Cu sintered compact. The reason was attributed to the high equilibrium gas pressure ratio of H2O/H2 in the reduction reaction of Cu or Ni oxide with H2. (2) The addition of iron powder to the Cu-Sn alloy powder was effective for the complete densification of the sintered compact in the same way as that of Cu powder, but not effective for the Cu-Ni alloy powder. This difference was thought to be due to the fact that unlike Cu and Sn, Ni dissolved in large quantities in the iron phase of the sintered compact and oxides with high equilibrium gas pressure ratio of H2O/H2 were formed in the Cu-Ni-Fe compact. (3) Therefore, the H2O/H2 equilibrium gas pressure ratio which is used as the criterion for the reduction of the oxide in the powder was considered to be a key parameter for the densification of the sintered compact after the isolation of pores.
