The dynamic tensile deformation and fracture behavior of the Zr-based metallic glass/porous W phase composite were investigated at room temperature by means of the Split Hopkinson Tension Bar （SHTB）.It was found tha...The dynamic tensile deformation and fracture behavior of the Zr-based metallic glass/porous W phase composite were investigated at room temperature by means of the Split Hopkinson Tension Bar （SHTB）.It was found that the composite exhibited no appreciable macroscopic plastic deformation prior to catastrophic fracture and the fracture surface was perpendicular to the axial direction.Substantive micro cracks were observed along the interface between W grains or the interface between the metallic glass phase and the W phase.Scanning electron microscopy （SEM） observations revealed that vein-like patterns,dimple-like patterns and substantive ridge-like structures were the typical fracture morphologies on the fracture surface for the metallic glass phase and the morphology of the W phase is a mixture of intergranular and transgranular fracture.Based on those results referred above,the dynamic tensile deformation and fracture mechanism of the Zr-based metallic glass/porous W phase composite were discussed in detail.展开更多
Most of the structural alloys’applications are under static,dynamic,and cyclic forms of loading.Ti-5553 alloy in the beta phase field is being investigated to confirm the mechanism of deformation and phase transforma...Most of the structural alloys’applications are under static,dynamic,and cyclic forms of loading.Ti-5553 alloy in the beta phase field is being investigated to confirm the mechanism of deformation and phase transformation upon quasi-static and dynamic compression.The Ti-5553 alloy was heat-treated at 900℃ (almost 50℃ above beta transus temperature)for one hour of soaking time followed by air quenching to achieve a fullyβphase field.After that,Dynamic compression(DC)by Split Hopkinson Pressure Bar(SHPB)and Quasi-static compression(QSC)were performed at a strain rate of~10^3)/s and 10^(-3)/s,respectively.Recovered specimens were thoroughly examined by using different tools,such as an Optical microscope(OM),Scanning electron microscope(SEM),High-resolution transmission electron microscope(HRTEM),and Electron backscatter diffraction(EBSD)to get the reliable data for justification of logical conclusions.It is found that the dominating mode of deformation was dislocation slip along with twinning({332}<113>)to some extent in both of QSC and DC,but sliding&spalling of the grain boundary is observed more in the former.Stress-induced phase transformation,i.e.,βtoα"andβtoω,took place in the grains saturated with dislocation slips,where the former transformation occurred simultaneously with{332}<113>twinning,whileβtoωtransformation was completed when a set of two adjacent(110)_(β)planes covered±1/6th of the total separation distance between two(next to each other)(111)_(β)planes,by equal but opposite shear in(111)_(β)direction,and it caused 3%shrinkage of two closed packed(110)_(β)planes after transformation.展开更多
The study aimed to shed light on the post deformation and damage behavior of an extruded Mg-Zn-Zr alloy under a ballistic impact.The results revealed that the initial microstructure consisted of both{0001}basal and{10...The study aimed to shed light on the post deformation and damage behavior of an extruded Mg-Zn-Zr alloy under a ballistic impact.The results revealed that the initial microstructure consisted of both{0001}basal and{1010}prismatic fiber texture.After impact,adiabatic shear bands,pronounce different twinning in big grains,,<c>,and<c+a>types of dislocations,and grain refinement through twinning induce recrystallization accommodated the strain,and absorbed∼65.7%of the energy during impact carried by a soft steel projectile.Interestingly,the deformation behavior at the top broad sides of the crater was entirely different.The weak basal texture was changed to a strong prismatic texture,which was further proved by typical sigmoidal compressive stress-strain curves.A revised model for the development of the ultra-fine grains adjacent to the crater has been proposed.The microhardness and yield strength was∼33%and∼40%higher and chiefly ascribed to strain hardening in ultra-fine grained near the surface of the perforation path.The exit of the perforation path was severely damaged and forms onion-shaped concentric rings which were comprised of melted zones,dimples,and cracks.Based on the all interesting findings,this study can be a clue for the development of the lightweight Mg alloy for military and aerospace applications.展开更多
基金support of the National Natural Science Foundation of China(Grant No.10872032)
文摘The dynamic tensile deformation and fracture behavior of the Zr-based metallic glass/porous W phase composite were investigated at room temperature by means of the Split Hopkinson Tension Bar （SHTB）.It was found that the composite exhibited no appreciable macroscopic plastic deformation prior to catastrophic fracture and the fracture surface was perpendicular to the axial direction.Substantive micro cracks were observed along the interface between W grains or the interface between the metallic glass phase and the W phase.Scanning electron microscopy （SEM） observations revealed that vein-like patterns,dimple-like patterns and substantive ridge-like structures were the typical fracture morphologies on the fracture surface for the metallic glass phase and the morphology of the W phase is a mixture of intergranular and transgranular fracture.Based on those results referred above,the dynamic tensile deformation and fracture mechanism of the Zr-based metallic glass/porous W phase composite were discussed in detail.
基金the financial assistance of the State Key Laboratory of explosion science and technology China (Grant No.YBKT17-06)
文摘Most of the structural alloys’applications are under static,dynamic,and cyclic forms of loading.Ti-5553 alloy in the beta phase field is being investigated to confirm the mechanism of deformation and phase transformation upon quasi-static and dynamic compression.The Ti-5553 alloy was heat-treated at 900℃ (almost 50℃ above beta transus temperature)for one hour of soaking time followed by air quenching to achieve a fullyβphase field.After that,Dynamic compression(DC)by Split Hopkinson Pressure Bar(SHPB)and Quasi-static compression(QSC)were performed at a strain rate of~10^3)/s and 10^(-3)/s,respectively.Recovered specimens were thoroughly examined by using different tools,such as an Optical microscope(OM),Scanning electron microscope(SEM),High-resolution transmission electron microscope(HRTEM),and Electron backscatter diffraction(EBSD)to get the reliable data for justification of logical conclusions.It is found that the dominating mode of deformation was dislocation slip along with twinning({332}<113>)to some extent in both of QSC and DC,but sliding&spalling of the grain boundary is observed more in the former.Stress-induced phase transformation,i.e.,βtoα"andβtoω,took place in the grains saturated with dislocation slips,where the former transformation occurred simultaneously with{332}<113>twinning,whileβtoωtransformation was completed when a set of two adjacent(110)_(β)planes covered±1/6th of the total separation distance between two(next to each other)(111)_(β)planes,by equal but opposite shear in(111)_(β)direction,and it caused 3%shrinkage of two closed packed(110)_(β)planes after transformation.
基金This project was financially supported by the National Natural Science Foundation of China(No.51702015)。
文摘The study aimed to shed light on the post deformation and damage behavior of an extruded Mg-Zn-Zr alloy under a ballistic impact.The results revealed that the initial microstructure consisted of both{0001}basal and{1010}prismatic fiber texture.After impact,adiabatic shear bands,pronounce different twinning in big grains,,<c>,and<c+a>types of dislocations,and grain refinement through twinning induce recrystallization accommodated the strain,and absorbed∼65.7%of the energy during impact carried by a soft steel projectile.Interestingly,the deformation behavior at the top broad sides of the crater was entirely different.The weak basal texture was changed to a strong prismatic texture,which was further proved by typical sigmoidal compressive stress-strain curves.A revised model for the development of the ultra-fine grains adjacent to the crater has been proposed.The microhardness and yield strength was∼33%and∼40%higher and chiefly ascribed to strain hardening in ultra-fine grained near the surface of the perforation path.The exit of the perforation path was severely damaged and forms onion-shaped concentric rings which were comprised of melted zones,dimples,and cracks.Based on the all interesting findings,this study can be a clue for the development of the lightweight Mg alloy for military and aerospace applications.
