MOLECULAR-DYNAMICS SIMULATION OF HYDROGEN ENHANCING DISLOCATION EMISSION

The interactive pair potential between Al and H is obtained based on t he ab initio calculation and the Chen-Mobius 3D lattice inversion form ula. By utilizing the pair potentials calculated, the effects oi hydro gen on the dislocation emission from crack tip have been studied. The simulated result shows that hydrogen can reduce the cohesive strength for Al single crystal, and then the critical stress intensity factor f or partial dislocation emission decreases from 0.11 MPa root m (C-H = 0) to 0.075 MPa root m (C-H=0.72%) and 0.06 MPa root m (C-H = 1.44%). This indicates thar hydrogen can enhance the dislocation emission. The simulation also shows that atoms oi hydrogen can gather and turn into small bubbles, resulting in enhancement of the equilibrium vacancy co ncentration.