A systematic study was made of symmetrical tilt grain boundaries lying about the <110> axis. The results showed that multiple structural phases, some of which incorporated vacancies, competed for the boundary ground state. It was found that, under low external stresses, vacancies preferred to bind to boundaries in high concentrations. An external stress drove structural phase transitions which corresponded to the switching of boundaries on and off as pipe-diffusion pathways for vacancies.

Atomic-Level Physics of Grain Boundaries in BCC Molybdenum. D.Yeşilleten, T.A.Arias: Physical Review B, 2001, 64[17], 174101 (6pp)