High-angle annular dark-field scanning transmission electron microscopy and selected area electron diffraction techniques were used to study the mechanism that underlies the influence of rapid cold-stamping deformatio...High-angle annular dark-field scanning transmission electron microscopy and selected area electron diffraction techniques were used to study the mechanism that underlies the influence of rapid cold-stamping deformation on the fracture behavior of the elongated nanoprecipitated phase in extruded Al−Cu−Mg alloy.Results show that the interface between the long strip-shaped S′phase and the aluminum matrix in the extruded Al−Cu−Mg alloy is flat and breaks during rapid cold-stamping deformation.The breaking mechanisms are distortion and brittle failure,redissolution,and necking.The breakage of the long strip S′phase increases the contact surface between the S′phase and the aluminum matrix and improves the interfacial distortion energy.This effect accounts for the higher free energy of the S′phase than that of the matrix and creates conditions for the redissolution of solute atoms back into the aluminum matrix.The brittle S′phase produces a resolved step during rapid cold-stamping deformation.This step further accelerates the diffusion of solute atoms and promotes the redissolution of the S′phase.Thus,the S′phase necks and separates,and the long strip-shaped S′phase in the extruded Al−Cu−Mg alloy is broken into a short and thin S′phase.展开更多
The M8.0 Wenchuan earthquake occurred on the Longmenshan fault zone. Based on field investigation of the surface rupture and focal mechanism study of the aftershocks, we discuss the geological relationship of the main...The M8.0 Wenchuan earthquake occurred on the Longmenshan fault zone. Based on field investigation of the surface rupture and focal mechanism study of the aftershocks, we discuss the geological relationship of the main, secondary and triggered ruptures. The main rupture is about 200km long and can be divided into the south part and the north part. The south part consists of two parallel fault zones characterized by reverse faulting, with several parallel secondary ruptures on the hanging wall of the main fault, and the north part is a single main fault zone characterized by lateral strike-slip and reverse faulting. Compared to a 300km long aftershock distribution, the surface rupture only occupies 200km, and the remaining lOOkm on the northeast of the main rupture was triggered by aftershocks. Study on the ruptures of this earthquake will be useful for studying the earthquake risk evolution on the Longmenshan fault system.展开更多
The May 12, 2008, Ms8.0 Wenchuan earthquake was the outcome of a recent movement of an active intra-continental thrust fault zone. The seismogenic fault of this earthquake underwent oblique-slip faulting along the cen...The May 12, 2008, Ms8.0 Wenchuan earthquake was the outcome of a recent movement of an active intra-continental thrust fault zone. The seismogenic fault of this earthquake underwent oblique-slip faulting along the central fault and pure thrust faulting along the range-front fault of the Longmenshan fault zone. The former had a steep dip and large vertical displacement, and the latter had a gentle dip and little vertical displacement. The fault zone consisted of compressive double fault ramps rup turing with right-lateral strike-slip components resulting from strain partitioning of a deep oblique slip fault in the brittle zone of the upper crust. The kinematic pattern and rupture mechanisms are complex for the seismogenic fault, as indicated by the geometric pattern of its surface ruptures, the coseismic displacement distribution and focal mechanisms of the main shock and aftershocks. As a tear fault, the NW-trending, left-lateral, strike-slip Xiaoyudong fault zone has accommodated NE-trending displacements with different shortening amounts. However, because of intense compression on the southwestern segment of the seismogenic fault, the left-lateral, strike-slip Xiaoyudong fault also carries a clear compression component. Normal faulting with a strike-slip component controls the formation of a fault-trough along the central fault, which is characterized by thrusting with a strike-slip component and strike-slip with thrusting. The fault-troughs are the product of the interaction of slip and grav ity on the seismogenic fault under specific geological and geomorphic conditions. Gravitational force exaggerated the vertical component of fault displacement, which by no means represents the actual maximum vertical displacement of the seismogenic fault.展开更多
基金Project(19A131)supported by Key Scientific Research Project of Hunan Province,ChinaProject(2019JJ60050)supported by the Natural Science Foundation of Hunan Province,China。
文摘High-angle annular dark-field scanning transmission electron microscopy and selected area electron diffraction techniques were used to study the mechanism that underlies the influence of rapid cold-stamping deformation on the fracture behavior of the elongated nanoprecipitated phase in extruded Al−Cu−Mg alloy.Results show that the interface between the long strip-shaped S′phase and the aluminum matrix in the extruded Al−Cu−Mg alloy is flat and breaks during rapid cold-stamping deformation.The breaking mechanisms are distortion and brittle failure,redissolution,and necking.The breakage of the long strip S′phase increases the contact surface between the S′phase and the aluminum matrix and improves the interfacial distortion energy.This effect accounts for the higher free energy of the S′phase than that of the matrix and creates conditions for the redissolution of solute atoms back into the aluminum matrix.The brittle S′phase produces a resolved step during rapid cold-stamping deformation.This step further accelerates the diffusion of solute atoms and promotes the redissolution of the S′phase.Thus,the S′phase necks and separates,and the long strip-shaped S′phase in the extruded Al−Cu−Mg alloy is broken into a short and thin S′phase.
基金sponsored by the Special Earthquake Research Program(20070851)National Key Basic Research Development Planning grogram(2004CB418401)+1 种基金Basic Science Research Professional of Institute of Crustal Dynamics (2008)National Science and Technology Support Program(2006BAC13B01 -0202),China
文摘The M8.0 Wenchuan earthquake occurred on the Longmenshan fault zone. Based on field investigation of the surface rupture and focal mechanism study of the aftershocks, we discuss the geological relationship of the main, secondary and triggered ruptures. The main rupture is about 200km long and can be divided into the south part and the north part. The south part consists of two parallel fault zones characterized by reverse faulting, with several parallel secondary ruptures on the hanging wall of the main fault, and the north part is a single main fault zone characterized by lateral strike-slip and reverse faulting. Compared to a 300km long aftershock distribution, the surface rupture only occupies 200km, and the remaining lOOkm on the northeast of the main rupture was triggered by aftershocks. Study on the ruptures of this earthquake will be useful for studying the earthquake risk evolution on the Longmenshan fault system.
基金supported by Wenchuan Fault Scientific Drilling Program
文摘The May 12, 2008, Ms8.0 Wenchuan earthquake was the outcome of a recent movement of an active intra-continental thrust fault zone. The seismogenic fault of this earthquake underwent oblique-slip faulting along the central fault and pure thrust faulting along the range-front fault of the Longmenshan fault zone. The former had a steep dip and large vertical displacement, and the latter had a gentle dip and little vertical displacement. The fault zone consisted of compressive double fault ramps rup turing with right-lateral strike-slip components resulting from strain partitioning of a deep oblique slip fault in the brittle zone of the upper crust. The kinematic pattern and rupture mechanisms are complex for the seismogenic fault, as indicated by the geometric pattern of its surface ruptures, the coseismic displacement distribution and focal mechanisms of the main shock and aftershocks. As a tear fault, the NW-trending, left-lateral, strike-slip Xiaoyudong fault zone has accommodated NE-trending displacements with different shortening amounts. However, because of intense compression on the southwestern segment of the seismogenic fault, the left-lateral, strike-slip Xiaoyudong fault also carries a clear compression component. Normal faulting with a strike-slip component controls the formation of a fault-trough along the central fault, which is characterized by thrusting with a strike-slip component and strike-slip with thrusting. The fault-troughs are the product of the interaction of slip and grav ity on the seismogenic fault under specific geological and geomorphic conditions. Gravitational force exaggerated the vertical component of fault displacement, which by no means represents the actual maximum vertical displacement of the seismogenic fault.
