Grain Boundary Wetting in Metals: 'Self Indentation-Internal Solution' Mechanism

Abstract

Under the thermodynamic condition of grain boundary wetting (GBW), the imbalance between GB and solid -liquid interphase surface tensions γ GB and γ SL creates a linear force applying at the root of the GB groove and pointing into the solid. The indentation action of this force is suggested to cause stress- driven self diffusion (diffusional creep) into the GB slab. This process drains the groove and leads to the deposition of the solid atoms along the GB (internal solution ). Assuming that the GB acts as a perfect sink, this self indentation -internal solution (SIIS) mechanism can account for the non-Mullins morphology and linear kinetics of GBW, the origin of the singular stress field at the wetting front, the expansion of the solid under GBW, the role of external stress, and the GBW transitions with temperature. The mechanism is considered in more detail in [1 ] where a summary of GBW observations in metals is also given.