An unusual F_(3)basal stacking fault resulting from twin-dislocation interaction in magnesium is observed in molecular dynamics simulation.The F_(3)fault is produced in the twin lattice from the interaction between a ...An unusual F_(3)basal stacking fault resulting from twin-dislocation interaction in magnesium is observed in molecular dynamics simulation.The F_(3)fault is produced in the twin lattice from the interaction between a migrating(1012)twin boundary and a partial dislocation of either a prismatic<c>edge,or a prismatic<c+a>mixed dislocation in the matrix.The condition is that the partial dislocation needs to have a negative sign and lie on a plane intersecting a compression site of the twin boundary.The F_(3)fault can also be generated when a positive basal<a>mixed dislocation in the twin lattice,with slip plane intersecting a compression site of the twin boundary,interacts with a basal-prismatic twinning disconnection.The F_(3)fault comprises two I_(1) faults that have the same character but are separated by two basal layers.It has one end connected to the twin boundary,and the other end bounded by a lattice defect with a Burgers vector identical to that of a 30°Shockley partial dislocation.The formation frequency of the F_(3)fault is higher at a lower shear stress(below∼400 MPa)and/or a lower temperature(100 K and 200 K).The F_(3)fault can decompose into a glissile 30°Shockley and a T_(2) fault at a temperature above∼400 K.The relationships between the F_(3)fault and other types of basal stacking faults such as I_(2),T_(2) or paired I_(1) faults that are separated by multiple basal layers are discussed.展开更多
Single-atomic-layer-height disconnections that connect with I1stacking faults are produced on{1011}twin boundaries in pure magnesium through transmutation of basalmixed dislocations across the twin boundaries,and thei...Single-atomic-layer-height disconnections that connect with I1stacking faults are produced on{1011}twin boundaries in pure magnesium through transmutation of basalmixed dislocations across the twin boundaries,and their stabilities are examined using molecular dynamics simulations.The stable configuration for a single-atomic-layer-height disconnection is a pyramidal-basal(PyB)disconnection connecting an I1fault associated with a stacking sequence change of ABACA,or a basal-pyramidal(BPy)disconnection connecting an I_(1)fault associated with a stacking sequence change of BABCB.A stable single-atomic-layer-height disconnection can transform to a less stable single-atomiclayer-height disconnection when its step orientation changes solely.A stable single-atomic-layer-height disconnection can also transform to another stable single-atomic-layer-height disconnection,when the step orientation of the disconnection and the type of the I_(1)fault that connects with the disconnection change synchronously,and this process is accompanied with the emission of a Shockley partial dislocation from the twin boundary.展开更多
基金the support from the Australian Research Council (DP200102985)the Monash Graduate ScholarshipInternational Postgraduate Research Scholarship
文摘An unusual F_(3)basal stacking fault resulting from twin-dislocation interaction in magnesium is observed in molecular dynamics simulation.The F_(3)fault is produced in the twin lattice from the interaction between a migrating(1012)twin boundary and a partial dislocation of either a prismatic<c>edge,or a prismatic<c+a>mixed dislocation in the matrix.The condition is that the partial dislocation needs to have a negative sign and lie on a plane intersecting a compression site of the twin boundary.The F_(3)fault can also be generated when a positive basal<a>mixed dislocation in the twin lattice,with slip plane intersecting a compression site of the twin boundary,interacts with a basal-prismatic twinning disconnection.The F_(3)fault comprises two I_(1) faults that have the same character but are separated by two basal layers.It has one end connected to the twin boundary,and the other end bounded by a lattice defect with a Burgers vector identical to that of a 30°Shockley partial dislocation.The formation frequency of the F_(3)fault is higher at a lower shear stress(below∼400 MPa)and/or a lower temperature(100 K and 200 K).The F_(3)fault can decompose into a glissile 30°Shockley and a T_(2) fault at a temperature above∼400 K.The relationships between the F_(3)fault and other types of basal stacking faults such as I_(2),T_(2) or paired I_(1) faults that are separated by multiple basal layers are discussed.
文摘Single-atomic-layer-height disconnections that connect with I1stacking faults are produced on{1011}twin boundaries in pure magnesium through transmutation of basalmixed dislocations across the twin boundaries,and their stabilities are examined using molecular dynamics simulations.The stable configuration for a single-atomic-layer-height disconnection is a pyramidal-basal(PyB)disconnection connecting an I1fault associated with a stacking sequence change of ABACA,or a basal-pyramidal(BPy)disconnection connecting an I_(1)fault associated with a stacking sequence change of BABCB.A stable single-atomic-layer-height disconnection can transform to a less stable single-atomiclayer-height disconnection when its step orientation changes solely.A stable single-atomic-layer-height disconnection can also transform to another stable single-atomic-layer-height disconnection,when the step orientation of the disconnection and the type of the I_(1)fault that connects with the disconnection change synchronously,and this process is accompanied with the emission of a Shockley partial dislocation from the twin boundary.
