Segregation of Alkali and Alkaline Earth Metals at ∑11(113)[110] Grain Boundary in Aluminum from First-Principles Calculations

摘要

The grain boundary segregation energies of Mg, Na, Ca, K and Sr at a symmetric tilt ∑11(113)[110] grain boundary were investigated in aluminum using the first-principles calculation. The relationship between the grain boundary segregation energies and the volume size factors were examined to understand the role of elastic strain energy in the grain boundary segregation energy. The grain boundary segregation energy decreased with the increase in the volume size factor. It has been explained that the solute atom larger in size than Al, which stores greater strain energy in the bulk, prefers the looser site at the grain boundary plane rather than in the bulk, to release the elastic strain energy. Furthermore, on the basis of the Rice-Wang model, the effects of grain boundary segregation on the embrittlement at the grain boundary were studied. The embrittlement potency indicates that the Mg, Na, Ca, K and Sr atoms serve as embrittler in the grain boundary.