Variation in electrical conductivity of metal powders during sintering

Conclusions

• 1. The drop in electrical resistance of compacts made from copper powder when the compacting pressure is increased is basically governed by plastic deformation; the latter may increase the contact surfaces by the same amount as sintering for 3 hr at 900°C.

• 2. The smaller the particle size of the powder, the higher the electrical resistances of green compacts; specimens made from highly dispersed powders have lower as-sintered electrical resistances than specimens made from powders of large particle sizes.

• 3. The Arrhenius equation holds good for the temperature relationship for the rate of change in the electrical resistances of specimens when sintered in the temperature ranges concerned; the calculated heats of activation for the sintering processes for copper and nickel are 17000 and 34000 cal/mol respectively; this coincides with the heats of activation of surface self-diffusion for copper and nickel.

• 4. The variation in the electrical resistances of Cu−Ni system alloys in relation to their compositions is similar to the same variation for cast alloys. The comparatively small deviation of the electrical resistances of the sintered Cu−Mo system alloys from the comparison values shows that the solubility of the components is not high.