Carbon/carbon composites modified by NiAl alloy were prepared using vacuum reactive melt infiltration methods with NiAl and titanium mixed powders as raw materials. The microstructures were investigated by scanning el...Carbon/carbon composites modified by NiAl alloy were prepared using vacuum reactive melt infiltration methods with NiAl and titanium mixed powders as raw materials. The microstructures were investigated by scanning electron microscopy. The fracture behavior, infiltration and oxidation mechanism were further discussed. The results indicated that NiAl alloy exhibited good wettability on the C/C preform because a TiC reaction layer formed at the interface. Multi-layer（PyC/TiC/NiAl＋TiC） coating evenly and compactly distributed on the surface of the carbon fiber in tubular form. The penetration depth of molten NiAl alloys depended on the reaction between the PyC and titanium. The impact fracture was inclined to along the interface between the NiAl permeability layer and C/C matrix. Al_2TiO_5 and TiO_2 formed on the surface, while the interior multi-layer tubular structure partially remained after oxidation at 1773 K for 30 min.展开更多
The interfacial interaction existing in the Ni ZrO 2 composite plating has been investigated. The experimental results show that no new phases were formed in the interfacial regions between matrix Ni and ZrO 2 part...The interfacial interaction existing in the Ni ZrO 2 composite plating has been investigated. The experimental results show that no new phases were formed in the interfacial regions between matrix Ni and ZrO 2 particles, but an orbital interaction through the mutual overlap of the d orbits does exist in the interfacial regions between Ni atoms and Zr 3+ ions.展开更多
Numerical simulation and experiments were introduced to develop AA4045/AA3003 cladding billets with different clad-ratios. The temperature fields, microstructures and mechanical properties near interface were investig...Numerical simulation and experiments were introduced to develop AA4045/AA3003 cladding billets with different clad-ratios. The temperature fields, microstructures and mechanical properties near interface were investigated in detail. The results show that cladding billets with different clad-ratios were fabricated successfully. Si and Mn elements diffused across the bonding interface and formed diffusion layer. With the increase of clad-layer thickness, the interfacial region transforms from semisolid-solid state to liquid-solid state and the diffusion layer increased from 10 to 25 μm. The hardness at interface is higher than that of AA3003 side but lower than that of the other side. The bonding strength increased with the clad-layer thickness, attributing to solution strengthening due to elements diffusion. The cladding billets were extruded into clad pipe by indirect extrusion process after homogenization. The clad pipe remained the interfacial characteristics of as-cast cladding billet and the heredity of clad-ratio during deformation was testified.展开更多
Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different s...Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different samples was observed,and the thermal conductivity of samples was measured by laser flash method.The optimal process parameters for preparing diamond/copper composites with high thermal conductivity were investigated.The results indicated that plating tungsten on diamond could modify the interface bonding.When the diamond was plated for 60 min,the coating appeared intact,uniform and flat,and the thermal conductivity of the sample could reach as high as 486 W/(m·K).The integrity and uniformity were more important than thickness for the coating.When the tungsten-plated diamond was further annealed,the metallurgical bonding between the coating and the diamond was enhanced,and the thermal conductivity rose to 559 W/(m·K).展开更多
In order to improve the mechanical properties and corrosion resistance of Mg alloys,the equal channel angular extrusion (ECAE)was employed to fabricate the Mg-5Gd-5Y/Mg-2Zn-1Gd(GW55/ZG21)laminated composites.After fab...In order to improve the mechanical properties and corrosion resistance of Mg alloys,the equal channel angular extrusion (ECAE)was employed to fabricate the Mg-5Gd-5Y/Mg-2Zn-1Gd(GW55/ZG21)laminated composites.After fabrication and annealing treatment,the microstructural evolution,phase constitution,microhardness,and bonding strength were investigated on the bonding interface zone of GW55/ZG21 laminated composites.The bonding interface zone of GW55/ZG21 laminated composites comprises a lot of Mg3(Y,Gd)2Zn3 particles along the bonding interface,some rod Mg24(Y,Gd)5 phases on GW55 side,and a precipitation free zone(PFZ)on ZG21 side.After annealing treatment,Mg3(Y,Gd)2Zn3 particles along the bonding interface increase, rod Mg24(Y,Gd)5 phases on GW55 side decrease,and PFZ is broadened.Meanwhile,the hardness on the bonding interface zone decreases and the bonding strength increases from 126 MPa to 162 MPa.展开更多
基金Project(2011CB605804) supported by the National Basic Research Development Program of ChinaProject(2015JJ3167) supported by the Natural Science Foundation of Hunan Province,ChinaProject(2013M531810) supported by the Postdoctoral Science Foundation of China
文摘Carbon/carbon composites modified by NiAl alloy were prepared using vacuum reactive melt infiltration methods with NiAl and titanium mixed powders as raw materials. The microstructures were investigated by scanning electron microscopy. The fracture behavior, infiltration and oxidation mechanism were further discussed. The results indicated that NiAl alloy exhibited good wettability on the C/C preform because a TiC reaction layer formed at the interface. Multi-layer（PyC/TiC/NiAl＋TiC） coating evenly and compactly distributed on the surface of the carbon fiber in tubular form. The penetration depth of molten NiAl alloys depended on the reaction between the PyC and titanium. The impact fracture was inclined to along the interface between the NiAl permeability layer and C/C matrix. Al_2TiO_5 and TiO_2 formed on the surface, while the interior multi-layer tubular structure partially remained after oxidation at 1773 K for 30 min.
文摘The interfacial interaction existing in the Ni ZrO 2 composite plating has been investigated. The experimental results show that no new phases were formed in the interfacial regions between matrix Ni and ZrO 2 particles, but an orbital interaction through the mutual overlap of the d orbits does exist in the interfacial regions between Ni atoms and Zr 3+ ions.
基金Project(2015B090926013)supported by the Science and Technology Program of Guangdong Province,ChinaProject(20170540307)supported by the Natural Science Foundation of Liaoning Province,China
文摘Numerical simulation and experiments were introduced to develop AA4045/AA3003 cladding billets with different clad-ratios. The temperature fields, microstructures and mechanical properties near interface were investigated in detail. The results show that cladding billets with different clad-ratios were fabricated successfully. Si and Mn elements diffused across the bonding interface and formed diffusion layer. With the increase of clad-layer thickness, the interfacial region transforms from semisolid-solid state to liquid-solid state and the diffusion layer increased from 10 to 25 μm. The hardness at interface is higher than that of AA3003 side but lower than that of the other side. The bonding strength increased with the clad-layer thickness, attributing to solution strengthening due to elements diffusion. The cladding billets were extruded into clad pipe by indirect extrusion process after homogenization. The clad pipe remained the interfacial characteristics of as-cast cladding billet and the heredity of clad-ratio during deformation was testified.
基金supported by the National Natural Science Foundation of China(No.11802125)。
文摘Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different samples was observed,and the thermal conductivity of samples was measured by laser flash method.The optimal process parameters for preparing diamond/copper composites with high thermal conductivity were investigated.The results indicated that plating tungsten on diamond could modify the interface bonding.When the diamond was plated for 60 min,the coating appeared intact,uniform and flat,and the thermal conductivity of the sample could reach as high as 486 W/(m·K).The integrity and uniformity were more important than thickness for the coating.When the tungsten-plated diamond was further annealed,the metallurgical bonding between the coating and the diamond was enhanced,and the thermal conductivity rose to 559 W/(m·K).
基金Project(2007CB613704)supported by the National Basic Research Program of ChinaProject(50874100)supported by the National Natural Science Foundation of China
文摘In order to improve the mechanical properties and corrosion resistance of Mg alloys,the equal channel angular extrusion (ECAE)was employed to fabricate the Mg-5Gd-5Y/Mg-2Zn-1Gd(GW55/ZG21)laminated composites.After fabrication and annealing treatment,the microstructural evolution,phase constitution,microhardness,and bonding strength were investigated on the bonding interface zone of GW55/ZG21 laminated composites.The bonding interface zone of GW55/ZG21 laminated composites comprises a lot of Mg3(Y,Gd)2Zn3 particles along the bonding interface,some rod Mg24(Y,Gd)5 phases on GW55 side,and a precipitation free zone(PFZ)on ZG21 side.After annealing treatment,Mg3(Y,Gd)2Zn3 particles along the bonding interface increase, rod Mg24(Y,Gd)5 phases on GW55 side decrease,and PFZ is broadened.Meanwhile,the hardness on the bonding interface zone decreases and the bonding strength increases from 126 MPa to 162 MPa.
