Numerical investigation into pressure-assisted sintering using fully coupled mechano-diffusional phase-field model

Abstract

To investigate the effect of contact stress between particles on the evolution of microstructure in pressure-assisted sintering, an improved fully coupled mechano-diffusional phase-field model (PFM) was presented, in which the design of the interpolation method for elastic modulus ensured that the normalised contact stress distribution was approximated to that in conventional contact problems. The immediate advantage was that the consequent strain energy in the contact and neck area could be directly characterised without additional approximate treatment.The simulation results showed that the sintering neck evolved under the joint action of the mechanical mechanism of elastic contact and the mass diffusion mechanism for pressure-assisted sintering. Elastic contact played a dominant role before significant neck growth in the early stage of sintering. As the neck grew, mass diffusion became the dominant factor, but the normalised contact stress distribution in the contact area always satisfied that of the elastic contact problem. Owing to the additional contribution of strain energy, the greater the pressure, the faster the sintering neck growth. Further study showed that the diffusion-induced stress hindered the growth of the sintering neck according to the presented fully coupled model presented, and that the strain energy stored within the contact area will accelerate the sintering process.