The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification pro...The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification process of Ti3AlC2. The effects of Sm2O2 doped CeO2 nano particles on mechanical properties of Ti3AlC2 were investigated. It was found that the presence of 20SDC nano particles in Ti3AlC2 was very effective to improve the mechanical properties of Ti3AlC2 without spoiling the unique characteristics of Ti3AlC2temary carbide.展开更多
Improving the plasticity of TiAl alloys at room temperature has been a longstanding challenge for the de-velopment of next-generation aerospace engines.By adopting the nacre-like architecture design strategy,we have o...Improving the plasticity of TiAl alloys at room temperature has been a longstanding challenge for the de-velopment of next-generation aerospace engines.By adopting the nacre-like architecture design strategy,we have obtained a novel heterogeneous lamellar Ti_(2)AlC/TiAl composite with superior strength-plasticity synergy,i.e.,compressive strength of∼2065 MPa and fracture strain of∼27%.A combination of micropil-lar compression and large-scale atomistic simulation has revealed that the superior strength-plasticity synergy is attributed to the collaboration of Ti_(2)AlC reinforcement,lamellar architecture and heteroge-neous interface.More specifically,multiple deformation modes in Ti_(2)AlC,i.e.,basal-plane dislocations,atomic-scale ripples and kink bands,could be activated during the compression,thus promoting the plas-tic deformation capability of composite.Meanwhile,the lamellar architecture could not only induce sig-nificant stress redistribution and crack deflection between Ti_(2)AlC and TiAl,but also generate high-density SFs and DTs interactions in TiAl,leading to an improved strength and strain hardening ability.In addi-tion,profuse unique Ti_(2)AlC(1¯10¯3)/TiAl(111)interfaces in the composite could dramatically contribute to the strength and plasticity due to the interface-mediated dislocation nucleation and obstruction mecha-nisms.These findings offer a promising paradigm for tailoring microstructure of TiAl matrix composites with extraordinary strength and plasticity at ambient temperature.展开更多
Textured Ti2AlC lamellar composites have been successfully fabricated by a new method in the present work.The composites exhibit high compressive strength of ca 2 GPa,fracture toughness of 8.5 MPa m1/2(//c-axis),flexu...Textured Ti2AlC lamellar composites have been successfully fabricated by a new method in the present work.The composites exhibit high compressive strength of ca 2 GPa,fracture toughness of 8.5 MPa m1/2(//c-axis),flexural strength of 735 MPa(//c-axis)and high hardness of 7.9 GPa(//c-axis).The strengthening mechanisms were discussed.The sintering and densification process was investigated and crystal orientation and microstructure were studied by electron backscattered diffraction techniques.The synthesis temperature is reduced to 1200?C by using high surface-to-volume ratio Ti2AlC nano flakes.The Lotgering orientation factor of Ti2 AlC and Ti3 AlC2{00 l}planes in the textured top surface reaches 0.74 and 0.49,respectively.This new route may shed light on resolving the difficulties encountered in large scale fabrication of textured MAX phases.展开更多
The oxidation behavior of Ti_3AlC_2-20 TiB_2 composite was studied at 500℃–900℃ in air. The composite showed a very low oxidation rate and followed a logarithmic oxidation law. The in-situ incorporation of TiB_2 su...The oxidation behavior of Ti_3AlC_2-20 TiB_2 composite was studied at 500℃–900℃ in air. The composite showed a very low oxidation rate and followed a logarithmic oxidation law. The in-situ incorporation of TiB_2 suppressed the anomalous rapid oxidation of the substrate Ti_3AlC_2 occurred near 600℃ by forming a protective B_2O_3 glass layer, and also improved the oxidation resistance of the MAX phase at intermediatetemperature.展开更多
Presents the investigation of as cast microstructures of high temperature α+α 2 titanium alloys matrix composites reinforced by particles and fabricated using a reaction synthesis method by XRD, OM and SEM which rev...Presents the investigation of as cast microstructures of high temperature α+α 2 titanium alloys matrix composites reinforced by particles and fabricated using a reaction synthesis method by XRD, OM and SEM which reveals that the matrix transformed into single phase α 2 from two phases α+α 2 and reinforcing phases become Ti 3AlC and TiC from single phase TiC as C content increases to a critical value, and Ti 3AlC precipitates during solidification processing and points out that the morphologies of TiC and Ti 3AlC are of short lath shape and near spherical shape, respectively, and lattice parameters of matrix α 2 increase with the increasing of C content, but the lattice parameter of reinforcing phase TiC is lower than standard lattice parameter of TiC due to the C defection in TiC.展开更多
文摘The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification process of Ti3AlC2. The effects of Sm2O2 doped CeO2 nano particles on mechanical properties of Ti3AlC2 were investigated. It was found that the presence of 20SDC nano particles in Ti3AlC2 was very effective to improve the mechanical properties of Ti3AlC2 without spoiling the unique characteristics of Ti3AlC2temary carbide.
基金the financial supports from the National Natural Science Foundation of China(No.52065009)the Joint Funds of the Science and Technology Foundation of Guizhou Province,China(No.20157219)the Science and Technology Planning Project of Guizhou Province,China(No.20191069).
基金the National Natural Science Foundation of China(Grant No.52101174)the State Key Lab of Advanced Metals and Materials(No.2022-Z15).
文摘Improving the plasticity of TiAl alloys at room temperature has been a longstanding challenge for the de-velopment of next-generation aerospace engines.By adopting the nacre-like architecture design strategy,we have obtained a novel heterogeneous lamellar Ti_(2)AlC/TiAl composite with superior strength-plasticity synergy,i.e.,compressive strength of∼2065 MPa and fracture strain of∼27%.A combination of micropil-lar compression and large-scale atomistic simulation has revealed that the superior strength-plasticity synergy is attributed to the collaboration of Ti_(2)AlC reinforcement,lamellar architecture and heteroge-neous interface.More specifically,multiple deformation modes in Ti_(2)AlC,i.e.,basal-plane dislocations,atomic-scale ripples and kink bands,could be activated during the compression,thus promoting the plas-tic deformation capability of composite.Meanwhile,the lamellar architecture could not only induce sig-nificant stress redistribution and crack deflection between Ti_(2)AlC and TiAl,but also generate high-density SFs and DTs interactions in TiAl,leading to an improved strength and strain hardening ability.In addi-tion,profuse unique Ti_(2)AlC(1¯10¯3)/TiAl(111)interfaces in the composite could dramatically contribute to the strength and plasticity due to the interface-mediated dislocation nucleation and obstruction mecha-nisms.These findings offer a promising paradigm for tailoring microstructure of TiAl matrix composites with extraordinary strength and plasticity at ambient temperature.
基金financially supported by the National Key R&D Program of China(Nos.2017YFB0306201 and 2016YFB0701303).
文摘Textured Ti2AlC lamellar composites have been successfully fabricated by a new method in the present work.The composites exhibit high compressive strength of ca 2 GPa,fracture toughness of 8.5 MPa m1/2(//c-axis),flexural strength of 735 MPa(//c-axis)and high hardness of 7.9 GPa(//c-axis).The strengthening mechanisms were discussed.The sintering and densification process was investigated and crystal orientation and microstructure were studied by electron backscattered diffraction techniques.The synthesis temperature is reduced to 1200?C by using high surface-to-volume ratio Ti2AlC nano flakes.The Lotgering orientation factor of Ti2 AlC and Ti3 AlC2{00 l}planes in the textured top surface reaches 0.74 and 0.49,respectively.This new route may shed light on resolving the difficulties encountered in large scale fabrication of textured MAX phases.
基金partially supported by the National Natural Science Foundation of China (No. 51102125, No. 51571205 and 51602140)the Foundation of Liaoning Educational Committee of China (No. LYB201618)partially by Foundation of Liaoning Province of China (No. 20170520130)
文摘The oxidation behavior of Ti_3AlC_2-20 TiB_2 composite was studied at 500℃–900℃ in air. The composite showed a very low oxidation rate and followed a logarithmic oxidation law. The in-situ incorporation of TiB_2 suppressed the anomalous rapid oxidation of the substrate Ti_3AlC_2 occurred near 600℃ by forming a protective B_2O_3 glass layer, and also improved the oxidation resistance of the MAX phase at intermediatetemperature.
文摘Presents the investigation of as cast microstructures of high temperature α+α 2 titanium alloys matrix composites reinforced by particles and fabricated using a reaction synthesis method by XRD, OM and SEM which reveals that the matrix transformed into single phase α 2 from two phases α+α 2 and reinforcing phases become Ti 3AlC and TiC from single phase TiC as C content increases to a critical value, and Ti 3AlC precipitates during solidification processing and points out that the morphologies of TiC and Ti 3AlC are of short lath shape and near spherical shape, respectively, and lattice parameters of matrix α 2 increase with the increasing of C content, but the lattice parameter of reinforcing phase TiC is lower than standard lattice parameter of TiC due to the C defection in TiC.
