First-principles calculations were performed to investigate the structures and energetics of {101n} coherent twin boundaries(CTBs) and glide twin boundaries(GTBs) in hexagonal close-packed(hcp) Ti. The formation mecha...First-principles calculations were performed to investigate the structures and energetics of {101n} coherent twin boundaries(CTBs) and glide twin boundaries(GTBs) in hexagonal close-packed(hcp) Ti. The formation mechanism of GTBs and their correlation with twin growth were fundamentally explored. Results suggested that GTBs can form from the gliding of CTBs, through their interaction with basal stacking fault. The gliding eventually restored the CTB structures by forming a pair of single-layer twinning disconnections. The pile-up of twinning disconnections should be responsible for the wide steps at twin boundaries as observed in high-resolution transmission electron microscopy, which can further promote twin growth. Possible effects of various alloying elements on pinning twin boundaries were also evaluated, to guide the strengthening design of Ti alloys.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 financial support from the National MCF Energy R&D Program of China (2018YFE0306100)the National Natural Science Foundation of China (51971249)the State Key Laboratory for Powder Metallurgy,Central South University,Changsha,China
文摘First-principles calculations were performed to investigate the structures and energetics of {101n} coherent twin boundaries(CTBs) and glide twin boundaries(GTBs) in hexagonal close-packed(hcp) Ti. The formation mechanism of GTBs and their correlation with twin growth were fundamentally explored. Results suggested that GTBs can form from the gliding of CTBs, through their interaction with basal stacking fault. The gliding eventually restored the CTB structures by forming a pair of single-layer twinning disconnections. The pile-up of twinning disconnections should be responsible for the wide steps at twin boundaries as observed in high-resolution transmission electron microscopy, which can further promote twin growth. Possible effects of various alloying elements on pinning twin boundaries were also evaluated, to guide the strengthening design of Ti alloys.
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.
