A microscopic model is presented, which describes the sintering of equal-sized spherical particles that differ in phase. A wetting phase diagram of sintering was developed that classifies the equilibrium shapes that can arise during sintering of two spheres with different surface energies. The formation and growth of the interface between the dissimilar phases was studied from the point of view of solid-state wetting. The three-dimensional computer simulation of interface-reaction-controlled sintering was conducted using the Surface Evolver program. The deviation of dynamic contact angle from its equilibrium value was proportional to the contact line velocity and inversely proportional to the triple junction mobility. The stability of particle cluster configuration in equilibrium was also examined using Cahn's concept on grain-boundary energy ratios in two-phase materials.