Computational study on the microstructural evolution and the change of electrical resistivity of sintered materials

The change of electrical resistivity of materials during sintering has been investigated. The evolution of two-dimensional microstructures during sintering was evaluated using Monte Carlo simulation featuring neck formation, grain growth, and contraction of the powder compacts. The overall electrical resistivity of the sintered microstructure, calculated by Kirchhoff's first law, was related to the microstructure development during sintering, depending on microstructural parameters such as size and distribution of grains and pores. The solid-state sintering process of monosized particles was divided into three regimes: neck formation, densification, and grain growth. The resistivity dropped significantly at the very initial stage due to neck formation, and decreased slowly as pores were annihilated, while it remained almost unchanged after complete pore removal. For the sintering of randomly packed random-sized particles, the electrical resistivity dropped at the initial stage due to the neck formation, and then continuously decreased by a combined effect of compact densification and grain growth.