Particle rearrangement during sintering of heterogeneous powder mixtures: A combined experimental and theoretical study

We studied the morphology evolution of individual three-particle W-Cu-W agglomerates during sintering anneals at 1000 °C. The angle between the lines connecting the centers of W and Cu particles decreased during annealing, provided its initial value was different from 180°. While the W particles retained their spherical shape during sintering, the shape of Cu particles changed significantly after long sintering times. Both the rate of the particles' rearrangement and the linear shrinkage of the particle pairs determined in the experiments increased with decreasing initial angle between the particles. We proposed an analytical model of sintering of cylindrical three-wire agglomerates controlled by self-diffusion of Cu atoms along the surface of Cu wire and along the W-Cu interphase boundary. The proposed model incorporates a thermodynamic method for calculating the distribution of chemical potential of metal atoms moving along the rigid cylindrical interphase boundary. The predictions of the model were in good agreement with the experimental data, underlying an important role played by capillary-driven diffusion in rearrangement of particles during sintering.