The Mo alloys reinforced by Al2O3 particles were fabricated by hydrothermal synthesis and powder metallurgy. The microstructures of Mo-Al2O3 alloys were studied by using XRD, SEM and TEM. The results show that Al2O3 p...The Mo alloys reinforced by Al2O3 particles were fabricated by hydrothermal synthesis and powder metallurgy. The microstructures of Mo-Al2O3 alloys were studied by using XRD, SEM and TEM. The results show that Al2O3 particles, existing as a stable hexagonal phase(α-Al2O3), are uniformly dispersed in Mo matrix. The ultrafine α-Al2O3 particles remarkably refine grain size and increase dislocation density of Mo alloys. Moreover, a good interfacial bonding zone between α-Al2O3 and Mo grain is obtained. The crystallographic orientations of the interface of the Al2O3 particles and Mo matrix are [111]a-Al2O3//[111]Mo and(112)a-Al2O3//(0 11)Mo. Due to the effect of secondary phase and dislocation strengthening, the yield strength of Mo-2.0 vol.%Al2O3 alloy annealed at 1200 ℃ is approximately 56.0% higher than that of pure Mo. The results confirm that the addition of Al2O3 particles is a promising method to improve the mechanical properties of Mo alloys.展开更多
Microstructure evolution and hardening effect of pure tungsten and W-1.5%ZrO_(2) alloy under carbon ion irradiation are investigated by using transmission electron microscopy and nano-indentation.Carbon ion irradiatio...Microstructure evolution and hardening effect of pure tungsten and W-1.5%ZrO_(2) alloy under carbon ion irradiation are investigated by using transmission electron microscopy and nano-indentation.Carbon ion irradiation is performed at 700℃ with irradiation damages ranging from 0.25 dpa to 2.0 dpa.The results show that the irradiation defect clusters are mainly in the form of dislocation loop.The size and density of dislocation loops increase with irradiation damages intensifying.The W-1.5%ZrO_(2) alloy has a smaller dislocation loop size than that of pure tungsten.It is proposed that the phase boundaries have the ability to absorb and annihilate defects and the addition of ZrO_(2) phase improves the sink strength for irradiation defects.It is confirmed that the W-1.5% ZrO_(2) alloy shows a smaller change in hardness than the pure tungsten after being irradiated.From the above results,we conclude that the addition of ZrO_(2) into tungsten can significantly reduce the accumulation of irradiated defects and improve the irradiation resistance behaviors of the tungsten materials.展开更多
Surface modification is a fascinating way to improve the compounding effect between inorganic fillers and polymers.In this study,zirconium tungsten phosphate(ZWP) with negative thermal expansion was surface modified b...Surface modification is a fascinating way to improve the compounding effect between inorganic fillers and polymers.In this study,zirconium tungsten phosphate(ZWP) with negative thermal expansion was surface modified by silane coupling agent 3-(Trimethoxysilyl)propyl methacrylate.The effects of surface modification and the modification mechanism were analyzed in detail by X-ray diffractometer,scanning electron microscopy,Fourier transform infrared spectroscopy and thermal mechanical analysis.The surface modification could effectively reduce the thermal expansion properties of the composite.When the added amount of 3-methacryloxypropyl trimethoxysilaneSilane(trade name:KH570) is 0.50 wt%,the thermal expansion coefficient of ZWP/Aromatic polyimide composite decreased by 9.76%.The surface modification also can effectively improve the dielectric performance of aromatic polyimides.The present work provides one new way to improve the thermal expansion behavior of composites.展开更多
The addition of the second phase into tungsten can significantly refine the grain size of tungsten alloys,and also play a role in dispersion strengthening,thus improving the properties of tungsten alloy.As a preparati...The addition of the second phase into tungsten can significantly refine the grain size of tungsten alloys,and also play a role in dispersion strengthening,thus improving the properties of tungsten alloy.As a preparation method of tungsten alloy powder,liquid-phase method avoids the disadvantage of mechanical alloying,and the obtained powder composition is accurate and controllable,with high purity and excellent uniformity.At present,the second phase particles used for dispersion strengthening tungsten alloys are mainly composed of oxides.Oxide particles can be synthesized and precipitated in nitrate solution through in situ chemical reaction,and are uniformly distributed in composite powder by mixing and stirring.Finally,the oxide dispersion strengthened tungsten alloy(ODS-W)was obtained by reduction and sintering.Liquid-phase methods for preparing ODS-W alloys include azeotropic distillation,sol-gel methods,freeze-drying,hydrothermal synthesis,spray-drying,etc.In this paper,several liquid-phase methods for preparing tungsten alloy composite powder precursors are reviewed,and their latest research progresses are discussed.In addition,the morphologies and properties of tungsten alloys prepared by different methods are compared,which provides guidance for preparing high-performance tungsten alloys.展开更多
基金Projects(U1704152,U1804124)supported by the National Natural Science Foundation of ChinaProject(174100510012)supported by Plan for Scientific Innovation Talent of Henan Province,China。
文摘The Mo alloys reinforced by Al2O3 particles were fabricated by hydrothermal synthesis and powder metallurgy. The microstructures of Mo-Al2O3 alloys were studied by using XRD, SEM and TEM. The results show that Al2O3 particles, existing as a stable hexagonal phase(α-Al2O3), are uniformly dispersed in Mo matrix. The ultrafine α-Al2O3 particles remarkably refine grain size and increase dislocation density of Mo alloys. Moreover, a good interfacial bonding zone between α-Al2O3 and Mo grain is obtained. The crystallographic orientations of the interface of the Al2O3 particles and Mo matrix are [111]a-Al2O3//[111]Mo and(112)a-Al2O3//(0 11)Mo. Due to the effect of secondary phase and dislocation strengthening, the yield strength of Mo-2.0 vol.%Al2O3 alloy annealed at 1200 ℃ is approximately 56.0% higher than that of pure Mo. The results confirm that the addition of Al2O3 particles is a promising method to improve the mechanical properties of Mo alloys.
基金Project supported by the President's Foundation of the ChinaAcademy of Engineering Physics(Grant No.YZJJLX2018003)the National Natural Science Foundation of China(Grant Nos.U2004180 and 12105261)the Program for Changjiang Scholars and Innovative Research Team in Universities,China(Grant No.IRT1234).
文摘Microstructure evolution and hardening effect of pure tungsten and W-1.5%ZrO_(2) alloy under carbon ion irradiation are investigated by using transmission electron microscopy and nano-indentation.Carbon ion irradiation is performed at 700℃ with irradiation damages ranging from 0.25 dpa to 2.0 dpa.The results show that the irradiation defect clusters are mainly in the form of dislocation loop.The size and density of dislocation loops increase with irradiation damages intensifying.The W-1.5%ZrO_(2) alloy has a smaller dislocation loop size than that of pure tungsten.It is proposed that the phase boundaries have the ability to absorb and annihilate defects and the addition of ZrO_(2) phase improves the sink strength for irradiation defects.It is confirmed that the W-1.5% ZrO_(2) alloy shows a smaller change in hardness than the pure tungsten after being irradiated.From the above results,we conclude that the addition of ZrO_(2) into tungsten can significantly reduce the accumulation of irradiated defects and improve the irradiation resistance behaviors of the tungsten materials.
基金supported by the national science foundation of china (Nos. 22071221, 21905252)the natural science foundation of Henan province (Nos. 182300410192, 212300410086)。
文摘Surface modification is a fascinating way to improve the compounding effect between inorganic fillers and polymers.In this study,zirconium tungsten phosphate(ZWP) with negative thermal expansion was surface modified by silane coupling agent 3-(Trimethoxysilyl)propyl methacrylate.The effects of surface modification and the modification mechanism were analyzed in detail by X-ray diffractometer,scanning electron microscopy,Fourier transform infrared spectroscopy and thermal mechanical analysis.The surface modification could effectively reduce the thermal expansion properties of the composite.When the added amount of 3-methacryloxypropyl trimethoxysilaneSilane(trade name:KH570) is 0.50 wt%,the thermal expansion coefficient of ZWP/Aromatic polyimide composite decreased by 9.76%.The surface modification also can effectively improve the dielectric performance of aromatic polyimides.The present work provides one new way to improve the thermal expansion behavior of composites.
基金supported by National Natural Science Foundation of China(no.U2004180)。
文摘The addition of the second phase into tungsten can significantly refine the grain size of tungsten alloys,and also play a role in dispersion strengthening,thus improving the properties of tungsten alloy.As a preparation method of tungsten alloy powder,liquid-phase method avoids the disadvantage of mechanical alloying,and the obtained powder composition is accurate and controllable,with high purity and excellent uniformity.At present,the second phase particles used for dispersion strengthening tungsten alloys are mainly composed of oxides.Oxide particles can be synthesized and precipitated in nitrate solution through in situ chemical reaction,and are uniformly distributed in composite powder by mixing and stirring.Finally,the oxide dispersion strengthened tungsten alloy(ODS-W)was obtained by reduction and sintering.Liquid-phase methods for preparing ODS-W alloys include azeotropic distillation,sol-gel methods,freeze-drying,hydrothermal synthesis,spray-drying,etc.In this paper,several liquid-phase methods for preparing tungsten alloy composite powder precursors are reviewed,and their latest research progresses are discussed.In addition,the morphologies and properties of tungsten alloys prepared by different methods are compared,which provides guidance for preparing high-performance tungsten alloys.
