EMBRITTLEMENT OF NANOCRYSTALLINE NICKEL BY LIQUID-METALS

Metallographic and fractographic tests of liquid metal embrittlement a re performed for nanocrystalline Ni-Hg systems. It is shown that the b ehaviour of nanocrystalline nickel under these conditions is close to that of ordinary polycrystalline materials. The presence of a stage of subcritical crack growth is demonstrated. As nanocrystalline grains h ave none of their own intrinsic dislocations, it is assumed that subcr itical crack growth in liquid metal environment can be realized throug h the mechanism of dissolution of atoms from the crack tip. This disso lution-condensation model of liquid metal embrittlement, developed for polycrystals, can also be applied to nanocrystals.