The effects of SiC particles(SiCp)on high temperature oxidation behavior of titanium matrix composites(TMCs)under different powder metallurgy processes were investigated.In situ Ti C+Ti_(5)Si_(3)reinforced titanium ma...The effects of SiC particles(SiCp)on high temperature oxidation behavior of titanium matrix composites(TMCs)under different powder metallurgy processes were investigated.In situ Ti C+Ti_(5)Si_(3)reinforced titanium matrix composites were prepared by discharge plasma sintering(SPS)and argon protective sintering(APS).The results show that the two processes have a negligible effect on the composition and hardness of the samples,but the hardness of the two samples is significantly improved by adding SiCp.The apparent porosity of SPS process is obviously smaller than that of APS process,whereas,the apparent porosity increases slightly with the addition of SiCp.The oxide layer thickness and mass gain of the samples obtained by SPS process are smaller than those obtained by APS process.The oxide thickness and mass gain of both processes are further reduced by adding SiCp.The SPS composites showed the best high temperature oxidation resistance.Therefore,TMCs with Si Cp by SPS can effectively improve the high-temperature oxidation behavior of the materials.展开更多
The formation mechanism of stoichiometry Ti_5Si_3 by mechanical alloying (MA)from elemental powders has been investigated. The results of XRD and SEM analyses of the powdershow that Ti_5Si_3 can be synthesized by MA i...The formation mechanism of stoichiometry Ti_5Si_3 by mechanical alloying (MA)from elemental powders has been investigated. The results of XRD and SEM analyses of the powdershow that Ti_5Si_3 can be synthesized by MA in a planetary mill with two different formationmechanisms. Ti_5Si_3 was formed gradually with the mechanical collusion reaction (MCR) mechanismunder a lower impact energy, and the Ti_5Si_3 was formed abruptly with the self-propagatinghigh-temperature synthesis (SHS) formation mechanism under a higher impact energy.展开更多
First principles study is reported for the band structures, site and angular momentum decomposed density of states. and the electronic charge density distributions in high-temperature structural materials D88-Ti5Si3 w...First principles study is reported for the band structures, site and angular momentum decomposed density of states. and the electronic charge density distributions in high-temperature structural materials D88-Ti5Si3 with the addition of low-rate metalloid: carbon, boron, nitrogen and oxygen. It shows that how the addition of metalloid atoms can stabilize Nowotny phase of Ti,Si3 from the viewpoint of the electron structure.展开更多
By doping gas transport agents (GTA), the combustion process and structural formation of SHS can be significantly varied. In this paper, Ti5Sis was synthesized by SHS method using AICI3·6H2O as GTA. The effect of...By doping gas transport agents (GTA), the combustion process and structural formation of SHS can be significantly varied. In this paper, Ti5Sis was synthesized by SHS method using AICI3·6H2O as GTA. The effect of GTA was studied by measuring combustion process parameters. XRD and SEM were used to determine the phases and microstructures of products. The structural formation of 7V6Si3 with different GTA contents was studied by CFQ method. Three mechanisms were deduced.展开更多
In the present work, in-situ Ti_(5)Si_(3) reinforced special brasses were prepared by melt reaction method. The synthesized Ti_(5)Si_(3) phase shows various morphologies in brasses with different Ti_(5)Si_(3) content,...In the present work, in-situ Ti_(5)Si_(3) reinforced special brasses were prepared by melt reaction method. The synthesized Ti_(5)Si_(3) phase shows various morphologies in brasses with different Ti_(5)Si_(3) content, and the3 D morphological evolution of primary Ti_(5)Si_(3)and its growth mechanism were investigated. The Ti_(5)Si_(3) crystal, which bears D8_(8) hexagonal crystal structure, grows along <0001> direction and is revealed by{1010} faces during growth. With the increase of Ti_(5)Si_(3) content in the brasses, the morphology of primary Ti_(5)Si_(3)significantly changes from fibers to hexagonal prisms to short-rods with hollow. In addition,the influence of Ti_(5)Si_(3) volume fraction and morphology on the wear behavior of special brass was also revealed. It was substantiated that the wear resistance increases with the increasing volume fraction of Ti_(5)Si_(3), and the corresponding wear mechanism changes from delamination to slight adhesive wear and abrasive wear. However, the friction coefficient shows an abnormal increase when most of the Ti_(5)Si_(3) containing hollows appears in the brass. That is mainly due to the fact that the Ti_(5)Si_(3) is easier to break and fall off resulted by the hollow as a crack source, which makes it unable to resist the plastic deformation of the contact surface during the sliding.展开更多
基金the National Natural Science Foundation of China(No.52004342)Innovation-driven Project of Central South University,China(No.150240015)Natural Science Fund for Outstanding Young Scholar of Hunan Province,China(No.2021JJ20065).
基金the supports of the National Natural Science Foundation of China (No. 51901153)Natural Science Foundation of Shanxi Province,China (No. 201901D211096)。
基金Funded by the Key Projects of Equipment Pre-research Foundation of the Ministry of Equipment Development of the Central Military Commission of China(No.6140922010201)the Key R&D Plan of Zhenjiang in 2018(No.GY2018021)。
文摘The effects of SiC particles(SiCp)on high temperature oxidation behavior of titanium matrix composites(TMCs)under different powder metallurgy processes were investigated.In situ Ti C+Ti_(5)Si_(3)reinforced titanium matrix composites were prepared by discharge plasma sintering(SPS)and argon protective sintering(APS).The results show that the two processes have a negligible effect on the composition and hardness of the samples,but the hardness of the two samples is significantly improved by adding SiCp.The apparent porosity of SPS process is obviously smaller than that of APS process,whereas,the apparent porosity increases slightly with the addition of SiCp.The oxide layer thickness and mass gain of the samples obtained by SPS process are smaller than those obtained by APS process.The oxide thickness and mass gain of both processes are further reduced by adding SiCp.The SPS composites showed the best high temperature oxidation resistance.Therefore,TMCs with Si Cp by SPS can effectively improve the high-temperature oxidation behavior of the materials.
文摘The formation mechanism of stoichiometry Ti_5Si_3 by mechanical alloying (MA)from elemental powders has been investigated. The results of XRD and SEM analyses of the powdershow that Ti_5Si_3 can be synthesized by MA in a planetary mill with two different formationmechanisms. Ti_5Si_3 was formed gradually with the mechanical collusion reaction (MCR) mechanismunder a lower impact energy, and the Ti_5Si_3 was formed abruptly with the self-propagatinghigh-temperature synthesis (SHS) formation mechanism under a higher impact energy.
文摘First principles study is reported for the band structures, site and angular momentum decomposed density of states. and the electronic charge density distributions in high-temperature structural materials D88-Ti5Si3 with the addition of low-rate metalloid: carbon, boron, nitrogen and oxygen. It shows that how the addition of metalloid atoms can stabilize Nowotny phase of Ti,Si3 from the viewpoint of the electron structure.
基金Supported by the National Natural Science Fund (No. 59872024) and the National Excellent Young Scientist Fund of China(No. 59925207).
文摘By doping gas transport agents (GTA), the combustion process and structural formation of SHS can be significantly varied. In this paper, Ti5Sis was synthesized by SHS method using AICI3·6H2O as GTA. The effect of GTA was studied by measuring combustion process parameters. XRD and SEM were used to determine the phases and microstructures of products. The structural formation of 7V6Si3 with different GTA contents was studied by CFQ method. Three mechanisms were deduced.
基金supported financially by the National Key Research and Development Program of China(Nos.2018YFE0306103 and 2017YFB0306105)the National Natural Science Foundation of China(Nos.51771040,51690163 and51525401)The Science and Technology Innovation Project of Ningbo(No.2018B10030)。
文摘In the present work, in-situ Ti_(5)Si_(3) reinforced special brasses were prepared by melt reaction method. The synthesized Ti_(5)Si_(3) phase shows various morphologies in brasses with different Ti_(5)Si_(3) content, and the3 D morphological evolution of primary Ti_(5)Si_(3)and its growth mechanism were investigated. The Ti_(5)Si_(3) crystal, which bears D8_(8) hexagonal crystal structure, grows along <0001> direction and is revealed by{1010} faces during growth. With the increase of Ti_(5)Si_(3) content in the brasses, the morphology of primary Ti_(5)Si_(3)significantly changes from fibers to hexagonal prisms to short-rods with hollow. In addition,the influence of Ti_(5)Si_(3) volume fraction and morphology on the wear behavior of special brass was also revealed. It was substantiated that the wear resistance increases with the increasing volume fraction of Ti_(5)Si_(3), and the corresponding wear mechanism changes from delamination to slight adhesive wear and abrasive wear. However, the friction coefficient shows an abnormal increase when most of the Ti_(5)Si_(3) containing hollows appears in the brass. That is mainly due to the fact that the Ti_(5)Si_(3) is easier to break and fall off resulted by the hollow as a crack source, which makes it unable to resist the plastic deformation of the contact surface during the sliding.
