B4Cp/6061Al composites have become important structural and functional materials and can be fabricated by powder metallurgy and subsequent hot rolling. In this work, the effects of the hot-pressing temperature on micr...B4Cp/6061Al composites have become important structural and functional materials and can be fabricated by powder metallurgy and subsequent hot rolling. In this work, the effects of the hot-pressing temperature on microstructures and mechanical behaviors of the B4Cp/6061Al composites were investigated. The results showed that compared with the T4 heat treated B4Cp/6061Al composite hot pressed at 560℃, the yield strength and failure strain of the composites hot pressed at 580℃ were increased to 235 MPa and 18.4%, respectively. This was associated with the interface bonding strength between the B4C particles and the matrix. However, the reaction products, identified to be MgAl2O4 phases, were detected in the composites hot pressed at 600℃. The formation of the MgAl2O4 phases resulted in the Mg depletion, thus reducing the yield strength to 203.5 MPa after the T4 heat treatment due to the effect of the solid solution strengthening being weakened. In addition, the variation of hardness and electrical conductivity was mainly related to the Mg content in the matrix. Based on the as-rolled microstructures observed by SEM, SR-μCT and fracture surfaces, the deformation schematic diagram was depicted to reflect the tensile deformation process of the composites.展开更多
Aluminum-matrix boron carbide (B4Cp/Al) is a kind of neutron absorbing material widely used in nuclear spent fuel storage. In order to improve the tensile property of B4Cp/Al composites, a new type of nano-Al2O3 parti...Aluminum-matrix boron carbide (B4Cp/Al) is a kind of neutron absorbing material widely used in nuclear spent fuel storage. In order to improve the tensile property of B4Cp/Al composites, a new type of nano-Al2O3 particle (Al2O3np) reinforced B4Cp/Al + Al2O3np composites were prepared by powder metallurgy method. The Monte Carlo particle transport program (MCNP) was used to determine the influence of Al2O3np on the thermal neutron absorptivity of composites. The universal material testing machine and scanning electron microscope (SEM) were used to study the mechanical properties, microstructure and fracture morphology of B4Cp/Al composites. The results indicated that the neutron absorption properties of B4Cp/Al composites were not affected by the addition of nano-Al2O3 particles in the range of 1 wt%-15 wt%. The addition of Al2O3np can obviously reduce the grain size of B4Cp/Al matrix metals thus improve the tensile strength of the composites. The addition threshold of Al2O3np is about 2.5 wt%. Both B4Cp and Al2O3np change the fracture characteristics of the composites from toughness to brittleness, and the latter is more important.展开更多
In this study, electrochemical corrosion tests, full-soak corrosion tests and associated microstructure analysis were conducted to investigate the corrosion behaviors of B4C/6061Al neutron absorber composites（NACs） ...In this study, electrochemical corrosion tests, full-soak corrosion tests and associated microstructure analysis were conducted to investigate the corrosion behaviors of B4C/6061Al neutron absorber composites（NACs） manufactured by powder metallurgy method in solutions having different boric acid（H3BO3） concentrations（500, 2500 and 10,000 ppm）. In electrochemical corrosion tests, B4C/6061Al NACs demonstrate the highest（short-term） corrosion resistance in the 2500 ppm H3BO3 solution. While for full-soak corrosion tests, the B4C/6061Al NACs show the highest（long-term） corrosion resistance in the 500 ppm H3BO3 solution. This difference is found to be mainly due to the formation of different surface morphologies during these two different corrosion tests. As noticed, a layer of Al（OH）3was formed on the composite surface during full-soak corrosion tests, but it cannot be found in the electrochemical corrosion tests. The full-soak corrosion mechanism of the B4C/6061Al NACs in the H3BO3 solution is found to be primarily determined by the dynamic balance between the formation and dissolution rates of the oxide film, which is mainly controlled by the density of H~＋ ions in the solution.展开更多
基金financial support of National Key Research and Development Program of China (No. 2017YFA0403803)the National Natural Science Foundation of China (Nos.51525401, 51774065, 51601028, 51690163)+1 种基金Dalian Support Plan for Innovation of High-level Talents (Top and Leading Talents, 2015R013)fundamental research funds for the central universities (Nos. DUT18RC(3)042, DUT17RC(3)108)
文摘B4Cp/6061Al composites have become important structural and functional materials and can be fabricated by powder metallurgy and subsequent hot rolling. In this work, the effects of the hot-pressing temperature on microstructures and mechanical behaviors of the B4Cp/6061Al composites were investigated. The results showed that compared with the T4 heat treated B4Cp/6061Al composite hot pressed at 560℃, the yield strength and failure strain of the composites hot pressed at 580℃ were increased to 235 MPa and 18.4%, respectively. This was associated with the interface bonding strength between the B4C particles and the matrix. However, the reaction products, identified to be MgAl2O4 phases, were detected in the composites hot pressed at 600℃. The formation of the MgAl2O4 phases resulted in the Mg depletion, thus reducing the yield strength to 203.5 MPa after the T4 heat treatment due to the effect of the solid solution strengthening being weakened. In addition, the variation of hardness and electrical conductivity was mainly related to the Mg content in the matrix. Based on the as-rolled microstructures observed by SEM, SR-μCT and fracture surfaces, the deformation schematic diagram was depicted to reflect the tensile deformation process of the composites.
基金Funded by Natural National Science Foundation of China(NSFC)(No.11305149)National High-Tech R&D Program(863 Program)(No.2013AA030704)。
文摘Aluminum-matrix boron carbide (B4Cp/Al) is a kind of neutron absorbing material widely used in nuclear spent fuel storage. In order to improve the tensile property of B4Cp/Al composites, a new type of nano-Al2O3 particle (Al2O3np) reinforced B4Cp/Al + Al2O3np composites were prepared by powder metallurgy method. The Monte Carlo particle transport program (MCNP) was used to determine the influence of Al2O3np on the thermal neutron absorptivity of composites. The universal material testing machine and scanning electron microscope (SEM) were used to study the mechanical properties, microstructure and fracture morphology of B4Cp/Al composites. The results indicated that the neutron absorption properties of B4Cp/Al composites were not affected by the addition of nano-Al2O3 particles in the range of 1 wt%-15 wt%. The addition of Al2O3np can obviously reduce the grain size of B4Cp/Al matrix metals thus improve the tensile strength of the composites. The addition threshold of Al2O3np is about 2.5 wt%. Both B4Cp and Al2O3np change the fracture characteristics of the composites from toughness to brittleness, and the latter is more important.
基金the financial support provided by ‘‘The Key Science and Technology Program of Shanxi Province, China’’ (Grant No. 20130321024)the College of Materials Science and Engineering at Taiyuan University of TechnologyShanxi Zhongtong High-Tech Co. Ltd
文摘In this study, electrochemical corrosion tests, full-soak corrosion tests and associated microstructure analysis were conducted to investigate the corrosion behaviors of B4C/6061Al neutron absorber composites（NACs） manufactured by powder metallurgy method in solutions having different boric acid（H3BO3） concentrations（500, 2500 and 10,000 ppm）. In electrochemical corrosion tests, B4C/6061Al NACs demonstrate the highest（short-term） corrosion resistance in the 2500 ppm H3BO3 solution. While for full-soak corrosion tests, the B4C/6061Al NACs show the highest（long-term） corrosion resistance in the 500 ppm H3BO3 solution. This difference is found to be mainly due to the formation of different surface morphologies during these two different corrosion tests. As noticed, a layer of Al（OH）3was formed on the composite surface during full-soak corrosion tests, but it cannot be found in the electrochemical corrosion tests. The full-soak corrosion mechanism of the B4C/6061Al NACs in the H3BO3 solution is found to be primarily determined by the dynamic balance between the formation and dissolution rates of the oxide film, which is mainly controlled by the density of H~＋ ions in the solution.
