Atomistic simulation of the effect of the dissolution and adsorption of hydrogen atoms on the fracture of α-Fe single crystal under tensile load

The local hydrogen distribution has significant influences on hydrogen embrittlement. In this work, mode-I fractures of (010)[100] pre-cracked α-Fe single crystal containing dissolved and absorbed hydrogen atoms are simulated by molecular dynamics and the time-stamped force-bias Monte Carlo methods. Statistics show that when located near the {112} plane, hydrogen atoms accelerate cleavage fracture and suppress the slip of {112}<111>; when located on the {110} plane, they promote martensite transformation and increase {110}<111> slip. Most adsorbed hydrogen atoms are concentrated near the inside of the crack surface and suppress fracture early by stress relaxation; therein concentrates stresses inside the matrix, and causes microvoid-coalescence fracture.