Abstract
We study the coalescence of two particles with different sizes by surface diffusion, in the presence of a grain boundary, through mathematical modelling, numerical computation and physical experiment. We propose a proper set of joining conditions at the triple junctions and show computationally the development of a curved grain boundary. A unique experiment for the sintering of two microscale particles using focused ion beam machining is designed and implemented with thin Cu foils. The evolution of the sintering couples found after different annealing times agrees qualitatively with the simulation results based on the model and the proposed joining conditions.