The flow softening is an important phenomenon during hot deformation of metallic materials.In the present work,a more evident flow softening of Ti-6 Al-4 V alloy when deformed in two-phase region was observed in coars...The flow softening is an important phenomenon during hot deformation of metallic materials.In the present work,a more evident flow softening of Ti-6 Al-4 V alloy when deformed in two-phase region was observed in coarser a grain sample,which was attributed to an accelerated dynamic transformation from harder α phase into β phases.Notably,full β microstructure was observed in coarse grain samples at strain of 1.2,while retained a phase was observed in fine a grain specimens.In the views of thermodynamics and crystallographic analysis,the in-depth mechanisms of dynamic transformation were further investigated.展开更多
The metastableα’phase and dislocation characteristics(e.g.,density and constituents)are of vital importance for the mechanical responses of(α+β)titanium alloys.In this work,to reveal the in-depth decomposition mec...The metastableα’phase and dislocation characteristics(e.g.,density and constituents)are of vital importance for the mechanical responses of(α+β)titanium alloys.In this work,to reveal the in-depth decomposition mechanisms of dislocations and metastableα’and their influences on mechanical properties in a Ti-6Al-4V(α+β)alloy,the thermal stability of different microstructures tailored by various cooling approaches were investigated utilizing scanning electron microscope,electron backscattered diffraction,transmission electron microscope and X-ray diffraction line profile analysis.The results showed that the initial characteristics ofα’andαlaths and dislocation density were influenced by the cooling methods remarkably.The thermal stability of Ti-6Al-4V alloy increased with decreasing cooling rate.The improvement in thermal stability can be ascribed by the decrement in dislocations,partitioning of the alloying elements and grain orientations variation of theα’lath andαphase.It is also found that the plastic strain accommodation ofβ→α’transformation was dominated by dislocations.During stabilization annealing treatments,the,and dislocations simultaneously decomposed.The decomposition of dislocations and metastableα’phase during various stabilization annealing and the particular twins and stacking faults microstructures formed during quenching have a great influence on the properties of the studied Ti-6Al-4V alloy.展开更多
基金supported financially by the National Natural Science Foundation of China(Nos.51674111 and 51874127)the Chinese Scholarship Council(No.CSC 201606130102)。
文摘The flow softening is an important phenomenon during hot deformation of metallic materials.In the present work,a more evident flow softening of Ti-6 Al-4 V alloy when deformed in two-phase region was observed in coarser a grain sample,which was attributed to an accelerated dynamic transformation from harder α phase into β phases.Notably,full β microstructure was observed in coarse grain samples at strain of 1.2,while retained a phase was observed in fine a grain specimens.In the views of thermodynamics and crystallographic analysis,the in-depth mechanisms of dynamic transformation were further investigated.
基金supported by the National Natural Science Foundation of China(51774124,52074114)Hunan Provincial Natural Science Foundation of China(2019JJ40017,2020JJ5062)Graduate Training and Innovation Practice Base of Hunan Province。
文摘The metastableα’phase and dislocation characteristics(e.g.,density and constituents)are of vital importance for the mechanical responses of(α+β)titanium alloys.In this work,to reveal the in-depth decomposition mechanisms of dislocations and metastableα’and their influences on mechanical properties in a Ti-6Al-4V(α+β)alloy,the thermal stability of different microstructures tailored by various cooling approaches were investigated utilizing scanning electron microscope,electron backscattered diffraction,transmission electron microscope and X-ray diffraction line profile analysis.The results showed that the initial characteristics ofα’andαlaths and dislocation density were influenced by the cooling methods remarkably.The thermal stability of Ti-6Al-4V alloy increased with decreasing cooling rate.The improvement in thermal stability can be ascribed by the decrement in dislocations,partitioning of the alloying elements and grain orientations variation of theα’lath andαphase.It is also found that the plastic strain accommodation ofβ→α’transformation was dominated by dislocations.During stabilization annealing treatments,the,and dislocations simultaneously decomposed.The decomposition of dislocations and metastableα’phase during various stabilization annealing and the particular twins and stacking faults microstructures formed during quenching have a great influence on the properties of the studied Ti-6Al-4V alloy.
