Stress fields at boundaries between contacting particles

Small metal particles in the size range 0.1 lm sometimes exhibit stress fringes near the contacting boundary as observed in the transmission electron microscope. The possible causes for these stress fields are investigated in terms of different models: adhesion, external forces (possibly magnetic), dislocations in the grain boundary area or ‘‘squeezed-in’’ extra material in the grain boundary zone. In all these cases high stresses are expected near the contacting area. Adhesion between particles becomes more apparent the smaller they are and is thus very important in nanotechnology.