Effect of porosity on mechanical behaviour of nanocrystalline metals

The understanding of deformation mechanisms in nanocrystalline metals is still not clear. At present, the role of grain boundary is gaining importance. Most of the studies are carried out through simulation methods. Nanocrystalline materials are normally porous in nature. In this work, the effect of porosity on the deformation behaviour (under compression) of nanocrystalline FCC metal (Pd) is investigated by molecular dynamics simulation. The results show that modulus of elasticity and flow stress of the nanocrystalline FCC metals decreases with increase in porosity. The atoms in grains adjacent to the pores are observed to move towards the void space. For a relaxed nanocrystalline metal, the grain boundary atoms are under compressive stress.