The properties of the combustion and deflagration to detonation transition(DDT)of Al/Fe_(2)O_(3)/RDX hybrid nanocomposites,a type of potentially novel lead-free primary explosives,were tested in weakly confined condit...The properties of the combustion and deflagration to detonation transition(DDT)of Al/Fe_(2)O_(3)/RDX hybrid nanocomposites,a type of potentially novel lead-free primary explosives,were tested in weakly confined conditions,and the interaction of Al/Fe_(2)O_(3)nanothermite and RDX in the DDT process was studied in detail.Results show that the amount of the Al/Fe_(2)O_(3)nanothermite has a great effect on the DDT properties of Al/Fe_(2)O_(3)/RDX nanocomposites.The addition of Al/Fe_(2)O_(3)nanothermite to RDX apparently improves the firing properties of RDX.A small amount of Al/Fe_(2)O_(3)nanothermite greatly increases the initial combustion velocity of Al/Fe_(2)O_(3)/RDX nanocomposites,accelerating their DDT process.When the contents of Al/Fe_(2)O_(3)nanothermite are less than 20 wt%,the DDT mechanisms of Al/Fe_(2)O_(3)/RDX nanocomposites follow the distinct abrupt mode,and are consistent with that of RDX,though their DDT processes are different.The RDX added into the Al/Fe_(2)O_(3)nanothermite increases the latter's peak combustion velocity and makes it generate the DDT when the RDX content is at least 10 wt%.RDX plays a key role in the shock compressive combustion,the formation and the properties of the DDT in the flame propagation of nanocomposites.Compared with RDX,the fast DDT of Al/Fe_(2)O_(3)/RDX nanocomposites could be obtained by adjusting the chemical constituents of nanocomposites.展开更多
The superplasticity behavior of Fe-28Al, Fe-28Al-2Ti, Fe-28Al-4Ti (all composition reported in this paper are in atomic percent) alloys has been investigated by tensile testing.optical microscopy and transmission elec...The superplasticity behavior of Fe-28Al, Fe-28Al-2Ti, Fe-28Al-4Ti (all composition reported in this paper are in atomic percent) alloys has been investigated by tensile testing.optical microscopy and transmission electron mocroscopy.Tensile test were performed at 700 to 900℃ under a strain rate range of about 10-5/s to 10-2/s. Maximum strain rate sensitivity index m was found to be 0.5 and the largest elongation reached 620%. The flow activation energy was measured to be 263kJ/mol for Fe-28Al and 191kJ/ mol for Fe-28Al-2Ti, which are much lower than the creep activation energy generally observed in Fe3Al alloys. After deformation grain size became much finer from about 100 μm to 20-30μm.As combined with TEM observations, we suggested that a continuous recrystallization process took place and superplasticity may arise from this process.展开更多
Based on YU’s solids and molecules emperical electron theory(EET), interface valence electron structure of TiC-Fe3Al composites was set up, and the valence electron density of different atomic states TiC and Fe3Al co...Based on YU’s solids and molecules emperical electron theory(EET), interface valence electron structure of TiC-Fe3Al composites was set up, and the valence electron density of different atomic states TiC and Fe3Al composites in various planes was determined. The results indicate that the electron density of (1 00)Fe3Al is consistent with that of (110)TiC in the first-class a pproximation, the absolute value of minimum electron density difference along the interface is 0.007 37 nm?2, and the relative value is 0.759%. (1 10)TiC //(100)Fe3Al preferred orientation is believed to benefit the formation of the cuboidal shape TiC. In the other hand, it shows that the particle growth is accompanied by the transport of electron, the deviation continuity of electron density intrinsically hinders the grain growth. The electron density of (100)TiC is not consistent with Fe3Al arbitrary crystallographic plane, thus it well explains that the increased titanium and carbon contents do not increase the size of large particles. The crystallographic orientation of (1 10)TiC //(100)Fe3Al will improve the mechanical properties. Therefore interface electron theory is an effective theoretical implement for designing excellent property of composites.展开更多
基金supported by National Nature Science Foundation of China(No.22075230)the financial support of the doctoral research foundation(No.19ZX7102)from Southwest University of Science and Technology。
文摘The properties of the combustion and deflagration to detonation transition(DDT)of Al/Fe_(2)O_(3)/RDX hybrid nanocomposites,a type of potentially novel lead-free primary explosives,were tested in weakly confined conditions,and the interaction of Al/Fe_(2)O_(3)nanothermite and RDX in the DDT process was studied in detail.Results show that the amount of the Al/Fe_(2)O_(3)nanothermite has a great effect on the DDT properties of Al/Fe_(2)O_(3)/RDX nanocomposites.The addition of Al/Fe_(2)O_(3)nanothermite to RDX apparently improves the firing properties of RDX.A small amount of Al/Fe_(2)O_(3)nanothermite greatly increases the initial combustion velocity of Al/Fe_(2)O_(3)/RDX nanocomposites,accelerating their DDT process.When the contents of Al/Fe_(2)O_(3)nanothermite are less than 20 wt%,the DDT mechanisms of Al/Fe_(2)O_(3)/RDX nanocomposites follow the distinct abrupt mode,and are consistent with that of RDX,though their DDT processes are different.The RDX added into the Al/Fe_(2)O_(3)nanothermite increases the latter's peak combustion velocity and makes it generate the DDT when the RDX content is at least 10 wt%.RDX plays a key role in the shock compressive combustion,the formation and the properties of the DDT in the flame propagation of nanocomposites.Compared with RDX,the fast DDT of Al/Fe_(2)O_(3)/RDX nanocomposites could be obtained by adjusting the chemical constituents of nanocomposites.
文摘The superplasticity behavior of Fe-28Al, Fe-28Al-2Ti, Fe-28Al-4Ti (all composition reported in this paper are in atomic percent) alloys has been investigated by tensile testing.optical microscopy and transmission electron mocroscopy.Tensile test were performed at 700 to 900℃ under a strain rate range of about 10-5/s to 10-2/s. Maximum strain rate sensitivity index m was found to be 0.5 and the largest elongation reached 620%. The flow activation energy was measured to be 263kJ/mol for Fe-28Al and 191kJ/ mol for Fe-28Al-2Ti, which are much lower than the creep activation energy generally observed in Fe3Al alloys. After deformation grain size became much finer from about 100 μm to 20-30μm.As combined with TEM observations, we suggested that a continuous recrystallization process took place and superplasticity may arise from this process.
基金Project(Q99F01) supported by the Natural Science Foundation of Shandong Province, China
文摘Based on YU’s solids and molecules emperical electron theory(EET), interface valence electron structure of TiC-Fe3Al composites was set up, and the valence electron density of different atomic states TiC and Fe3Al composites in various planes was determined. The results indicate that the electron density of (1 00)Fe3Al is consistent with that of (110)TiC in the first-class a pproximation, the absolute value of minimum electron density difference along the interface is 0.007 37 nm?2, and the relative value is 0.759%. (1 10)TiC //(100)Fe3Al preferred orientation is believed to benefit the formation of the cuboidal shape TiC. In the other hand, it shows that the particle growth is accompanied by the transport of electron, the deviation continuity of electron density intrinsically hinders the grain growth. The electron density of (100)TiC is not consistent with Fe3Al arbitrary crystallographic plane, thus it well explains that the increased titanium and carbon contents do not increase the size of large particles. The crystallographic orientation of (1 10)TiC //(100)Fe3Al will improve the mechanical properties. Therefore interface electron theory is an effective theoretical implement for designing excellent property of composites.
