SOLID-PHASE SINTERING OF POWDER MIXTURE C OMPACTS WITH COMPLETE SOLUBILITY OF THE COMPONENTS

The influence of interdiffusion (homogenization) on the densification was investigated in the systems Ni - Co and Ni - Cu, whereby the diffu sion coefficients of the single elements differ significantly from eac h other (D(Co) almost-equal-to D(Ni); D(Cu) > D(Ni). Besides the nonis othermal and isothermal shrinkage as well as their velocity, the devel opment of the degree of homogenization and the defect state was determ ined. The shrinkage behaviour of Ni - Co compacts lies between those o f Ni and Co compacts. There is a nearly linear correlation between shr inkage and concentration. Therefore, the densification process of the mixtures is dominated by the same defect-activated material-transport mechanisms like in single-component systems. The interdiffusion exerts only a minor influence. However. in Ni - Cu sintering samples, which have a mean composition as well as a ''Cu < 50 %'' composition, the in terdiffusion leads to a deviating behaviour. This is caused by the res ulting Cu diffusion stream and this again results in a volume increase of the former Ni particles and the diffusion porosity in the former C u particles.