The microstructure evolution and deformation mechanism of a DZ125 superalloy during high-temperature creep were studied by means of microstructure observation and creep-property tests.The results show that at the init...The microstructure evolution and deformation mechanism of a DZ125 superalloy during high-temperature creep were studied by means of microstructure observation and creep-property tests.The results show that at the initial stage of high-temperature creep,two sets of dislocations with different Burgers vectors move and meet inγmatrix channels,and react to form a quadrilateral dislocation network.Andγ′phases with raft-like microstructure are generated after the formation of dislocation networks.As creep progresses,the quadrilateral dislocation network is gradually transformed into hexagonal and quadrilateral dislocation networks.During steady stage of creep,the superalloy undergoes deformation with the mechanism that a great number of dislocations slip and climb in the matrix across the raft-likeγ′phases.At the later stage of creep,the raft-likeγ′phases are sheared by dislocations at the breakage of dislocation networks,and then alternate slip occurs,which distorts and breaks the raft-likeγ′/γphases,resulting in the accumulation of micropores at the raft-likeγ′/γinterfaces and the formation of microcracks.As creep continues,the microcracks continue to expand until creep fracture occurs,which is the damage and fracture mechanism of the alloy at the later stage of creep at high temperature.展开更多
The melting and solidification process of DZ411 superalloy at different cooling rates(50,200,500°C/min)was observed in situ by high-temperature confocal laser scanning microscopy.The solidification behaviour of t...The melting and solidification process of DZ411 superalloy at different cooling rates(50,200,500°C/min)was observed in situ by high-temperature confocal laser scanning microscopy.The solidification behaviour of this alloy was also studied through other methods such as differential scanning calorimetry and scanning electron microscopy.The results show that the precipitation sequence of the main phases during the solidification of DZ411 alloy isγmatrix phase,carbide phase and Laves phase.Besides,during the solidification process of DZ411 alloy,both the dendrite thickness and dendrite spacing decreased with the increasing of cooling rate.In addition,a large amount of Ta is enriched in the dendrite stems at the end of solidification,which is the main reason for the formation of Laves phase.As the cooling rate increases,the size of the Laves phase becomes smaller and the distribution becomes more dispersed,which effectively inhibits the segregation of the alloy.展开更多
基金Guizhou Province Science and Technology Plan Project(QKHJC-ZK[2024]yiban604)Guizhou Province Science and Technology Plan Project(CXTD[2021]008)+4 种基金Bijie City Science and Technology Project(BKLH[2023]9)Technology Project of Bijie City(BKLH[2023]36)Natural Science Research Project of Guizhou Higher Education Institutions of China(QJJ[2023]047)Science and Technology Project of Guizhou Department of Transportation(2022-121-011)Sanmenxia City Science and Technology Bureau Science and Technology Research Project(2022002005)。
文摘The microstructure evolution and deformation mechanism of a DZ125 superalloy during high-temperature creep were studied by means of microstructure observation and creep-property tests.The results show that at the initial stage of high-temperature creep,two sets of dislocations with different Burgers vectors move and meet inγmatrix channels,and react to form a quadrilateral dislocation network.Andγ′phases with raft-like microstructure are generated after the formation of dislocation networks.As creep progresses,the quadrilateral dislocation network is gradually transformed into hexagonal and quadrilateral dislocation networks.During steady stage of creep,the superalloy undergoes deformation with the mechanism that a great number of dislocations slip and climb in the matrix across the raft-likeγ′phases.At the later stage of creep,the raft-likeγ′phases are sheared by dislocations at the breakage of dislocation networks,and then alternate slip occurs,which distorts and breaks the raft-likeγ′/γphases,resulting in the accumulation of micropores at the raft-likeγ′/γinterfaces and the formation of microcracks.As creep continues,the microcracks continue to expand until creep fracture occurs,which is the damage and fracture mechanism of the alloy at the later stage of creep at high temperature.
基金funded by the Key Science and Technology Projects of Gansu Province(Grant No.252DGA006)Central Fund for Guiding Local Science and Technology Development Projects(Grant No.25ZYJB001)+3 种基金Gansu Key Research and Development Project(Grant No.23YFGA0003)Gansu Provincial Joint Research Fund(Grant No.24JRRB004)the Industry support plan of Gansu Universities(Grant No.2024CYZC-01)the Science and Technology Projects of Jiayuguan City(No.24-10,QKJ24-01,QKJ24-10).
文摘The melting and solidification process of DZ411 superalloy at different cooling rates(50,200,500°C/min)was observed in situ by high-temperature confocal laser scanning microscopy.The solidification behaviour of this alloy was also studied through other methods such as differential scanning calorimetry and scanning electron microscopy.The results show that the precipitation sequence of the main phases during the solidification of DZ411 alloy isγmatrix phase,carbide phase and Laves phase.Besides,during the solidification process of DZ411 alloy,both the dendrite thickness and dendrite spacing decreased with the increasing of cooling rate.In addition,a large amount of Ta is enriched in the dendrite stems at the end of solidification,which is the main reason for the formation of Laves phase.As the cooling rate increases,the size of the Laves phase becomes smaller and the distribution becomes more dispersed,which effectively inhibits the segregation of the alloy.
