Nb-doped TiC ceramic,or (NbyTi1-y) Cx,in which amount of Nb element added is increased from zero to 40Wt. %, synthisized -with self-propagating high temperature synthesis,is studied with SCF-Xa-DV,a quantum chemistry ...Nb-doped TiC ceramic,or (NbyTi1-y) Cx,in which amount of Nb element added is increased from zero to 40Wt. %, synthisized -with self-propagating high temperature synthesis,is studied with SCF-Xa-DV,a quantum chemistry cal-culating method. The chemical bonding is studied to discuss the relation between structrues and properties. Several classes of models in which there is no vacancy,one vacancy or two vacan-cies have been calculated. From the calculated results of bond or-der, a measure of covalent bond strength,and molecule orbital contour map, it is concluded that when Nb element added in-creases, the vacancies increase correspondingly,the covalent com-ponent of chemical bonds of the samples decreases -while the met-al-bonding component increases, so the hardness and resistance of the samples decrease.展开更多
The morphology. orientation relationship and stability of TiC/γ interface in Fe-Cr-Ni base composite synthesized with a liquid state in-situ process have been studied. The TiC/γ interface in as-cast sample is of coh...The morphology. orientation relationship and stability of TiC/γ interface in Fe-Cr-Ni base composite synthesized with a liquid state in-situ process have been studied. The TiC/γ interface in as-cast sample is of coherent feature. Its orientation relationship is (020)γ／／(220)TiC, [001]γ||[001]TiC. During the aging at 1473 K, the TiC/γ interface may dissolve in matrix and lamellar M23C6 compound may precipitate from γ-matrix.展开更多
The conventional melting methods were used to obtain in situ TiC particle-reinforced dual-phase steel,followed by hot rolling and heat treatment processes.The aim was to investigate the effect of TiC particles on the ...The conventional melting methods were used to obtain in situ TiC particle-reinforced dual-phase steel,followed by hot rolling and heat treatment processes.The aim was to investigate the effect of TiC particles on the fracture behavior of dual-phase steel at different annealing temperatures,by analyzing the microstructure and tensile behavior of the multiscale TiC particle-reinforced dual-phase steel.The results showed that TiC particles precipitated in the as-cast microstructure of dual-phase steel were distributed along the grain boundaries.During hot rolling,the grain boundary-like morphology of the micron-sized TiC particles was disrupted,and the particles became more refined and evenly distributed in the matrix.The tensile tests revealed that the strength of the TiC particle-reinforced dual-phase steel increased with increasing martensite content,while the elongation decreased.These results were similar to those of conventional steel.The addition of 1 vol.%multiscale TiC particles improved the strength of the dual-phase steel but did not affect elongation of the steel.Cracks and holes were primarily concentrated around the TiC particles rather than at the interface of martensite and ferrite.The main causes of crack sprouting were TiC particle interface cracking and TiC particle internal fragmentation.Overall,the study demonstrated the potential of multiscale TiC particle-reinforced dual-phase steel as a strong and tough material.The refined distribution of TiC particles in the matrix improved the strength of the material without compromising its elongation.The results also highlighted the importance of careful selection of reinforcement particles to avoid detrimental effects on the fracture behavior of the material.展开更多
The character of structural changes in the surface layer of titanium carbide （TiC） with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The...The character of structural changes in the surface layer of titanium carbide （TiC） with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The thermal influence of the electron-beam irradiation on the surface layer microstructure of the composite fine-grained material was mathematically analyzed. Quantitative estimations of the depth of the zone in microstructural phase transformations were carried out. The microstructure and concentration profile of Ti distribution in the metallic binder over the cross section of the surface layer with microstructural phase transformations after electron-pulse treatment of the hard metal surface were experimentally investigated.展开更多
文摘Nb-doped TiC ceramic,or (NbyTi1-y) Cx,in which amount of Nb element added is increased from zero to 40Wt. %, synthisized -with self-propagating high temperature synthesis,is studied with SCF-Xa-DV,a quantum chemistry cal-culating method. The chemical bonding is studied to discuss the relation between structrues and properties. Several classes of models in which there is no vacancy,one vacancy or two vacan-cies have been calculated. From the calculated results of bond or-der, a measure of covalent bond strength,and molecule orbital contour map, it is concluded that when Nb element added in-creases, the vacancies increase correspondingly,the covalent com-ponent of chemical bonds of the samples decreases -while the met-al-bonding component increases, so the hardness and resistance of the samples decrease.
文摘The morphology. orientation relationship and stability of TiC/γ interface in Fe-Cr-Ni base composite synthesized with a liquid state in-situ process have been studied. The TiC/γ interface in as-cast sample is of coherent feature. Its orientation relationship is (020)γ／／(220)TiC, [001]γ||[001]TiC. During the aging at 1473 K, the TiC/γ interface may dissolve in matrix and lamellar M23C6 compound may precipitate from γ-matrix.
基金the National Basic Research Program,China(No.2022YFB3705300)National Natural Science Foundation of China(Nos.52274380,51874089,and U1960112)LiaoNing Revitalization Talents Program(XLYC2007030).
文摘The conventional melting methods were used to obtain in situ TiC particle-reinforced dual-phase steel,followed by hot rolling and heat treatment processes.The aim was to investigate the effect of TiC particles on the fracture behavior of dual-phase steel at different annealing temperatures,by analyzing the microstructure and tensile behavior of the multiscale TiC particle-reinforced dual-phase steel.The results showed that TiC particles precipitated in the as-cast microstructure of dual-phase steel were distributed along the grain boundaries.During hot rolling,the grain boundary-like morphology of the micron-sized TiC particles was disrupted,and the particles became more refined and evenly distributed in the matrix.The tensile tests revealed that the strength of the TiC particle-reinforced dual-phase steel increased with increasing martensite content,while the elongation decreased.These results were similar to those of conventional steel.The addition of 1 vol.%multiscale TiC particles improved the strength of the dual-phase steel but did not affect elongation of the steel.Cracks and holes were primarily concentrated around the TiC particles rather than at the interface of martensite and ferrite.The main causes of crack sprouting were TiC particle interface cracking and TiC particle internal fragmentation.Overall,the study demonstrated the potential of multiscale TiC particle-reinforced dual-phase steel as a strong and tough material.The refined distribution of TiC particles in the matrix improved the strength of the material without compromising its elongation.The results also highlighted the importance of careful selection of reinforcement particles to avoid detrimental effects on the fracture behavior of the material.
文摘The character of structural changes in the surface layer of titanium carbide （TiC） with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The thermal influence of the electron-beam irradiation on the surface layer microstructure of the composite fine-grained material was mathematically analyzed. Quantitative estimations of the depth of the zone in microstructural phase transformations were carried out. The microstructure and concentration profile of Ti distribution in the metallic binder over the cross section of the surface layer with microstructural phase transformations after electron-pulse treatment of the hard metal surface were experimentally investigated.
