Microstructure stability of in situ synthesized Ti2AlN/Ti-48Al-2Cr-2Nb composite during aging at 900 ℃ was investigated by XRD, OM and TEM, and the unreinforced Ti-48Al-2Cr-2Nb alloy was also examined for comparison....Microstructure stability of in situ synthesized Ti2AlN/Ti-48Al-2Cr-2Nb composite during aging at 900 ℃ was investigated by XRD, OM and TEM, and the unreinforced Ti-48Al-2Cr-2Nb alloy was also examined for comparison. The result showed that in the TiAl alloy,α2 lamellae thinned and were broken down, and became discontinuous with increasing aging time. The decomposition ofα2 lamella toγ which was characterized by parallel decomposition and breakdown ofα2 lamellae led to the degradation of the lamellar structure. While in the composite, lamellar structure remained relatively stable even after aging at 900 ℃ for 100 h. No breakdown ofα2 lamellae except parallel decomposition and precipitation of fine nitride particles was observed. The better microstructural stability of the composite was mainly attributed to the precipitation of Ti2AlN particles at theα2/γ interface which played an important role in retarding the coarsening of lamellar microstructure in the matrix of composite.展开更多
This study develops a method for the full-size structural design of blade,involving the optimal layer thickness configuration of the blade to maximize its bending stiffness using a genetic algorithm.Numerical differen...This study develops a method for the full-size structural design of blade,involving the optimal layer thickness configuration of the blade to maximize its bending stiffness using a genetic algorithm.Numerical differentiation is employed to solve the sensitivity of blade modal frequency to the layer thickness of each part of blade.The natural frequencies of first-order flapwise and edgewise modes are selected as the optimal objectives.Based on the modal sensitivity analysis of all design variables,the effect of discretized layer thickness on bending stiffness of the blade is explored,and 14 significant design variables are filtered to drive the structural optimization.The best solution predicts an increase in natural frequencies of first-order flapwise and edgewise blade modes by up to 12%and 10.4%,respectively.The results show that the structural optimization method based on modal sensitivity is more effective to improve the structural performance.展开更多
基金Project(2011CB605502)supported by the National Basic Research Program of ChinaProject(B08040)supported by Introducing Talents of Discipline to Universities,China
文摘Microstructure stability of in situ synthesized Ti2AlN/Ti-48Al-2Cr-2Nb composite during aging at 900 ℃ was investigated by XRD, OM and TEM, and the unreinforced Ti-48Al-2Cr-2Nb alloy was also examined for comparison. The result showed that in the TiAl alloy,α2 lamellae thinned and were broken down, and became discontinuous with increasing aging time. The decomposition ofα2 lamella toγ which was characterized by parallel decomposition and breakdown ofα2 lamellae led to the degradation of the lamellar structure. While in the composite, lamellar structure remained relatively stable even after aging at 900 ℃ for 100 h. No breakdown ofα2 lamellae except parallel decomposition and precipitation of fine nitride particles was observed. The better microstructural stability of the composite was mainly attributed to the precipitation of Ti2AlN particles at theα2/γ interface which played an important role in retarding the coarsening of lamellar microstructure in the matrix of composite.
基金supported by the National Natural Science Foundation of China(Nos.51965034,51565028)the Lanzhou City Innovation and Entrepreneurship Project(No.2018-RC-25)。
文摘This study develops a method for the full-size structural design of blade,involving the optimal layer thickness configuration of the blade to maximize its bending stiffness using a genetic algorithm.Numerical differentiation is employed to solve the sensitivity of blade modal frequency to the layer thickness of each part of blade.The natural frequencies of first-order flapwise and edgewise modes are selected as the optimal objectives.Based on the modal sensitivity analysis of all design variables,the effect of discretized layer thickness on bending stiffness of the blade is explored,and 14 significant design variables are filtered to drive the structural optimization.The best solution predicts an increase in natural frequencies of first-order flapwise and edgewise blade modes by up to 12%and 10.4%,respectively.The results show that the structural optimization method based on modal sensitivity is more effective to improve the structural performance.
