This study presents the fabrication of 14CrFe-Cr-Al oxide dispersion strengthened(ODS)alloy by a direct oxidation process.In order to explain how oxide nanoparticles are formed in the consolidation process,the powders...This study presents the fabrication of 14CrFe-Cr-Al oxide dispersion strengthened(ODS)alloy by a direct oxidation process.In order to explain how oxide nanoparticles are formed in the consolidation process,the powders after oxidation are subjected to vacuum thermal treatment at high temperatures.Differential scanning calorimeter,X-ray photoelectron spectroscopy,scanning electron microscopy and transmission electron microscopy techniques are used to detect the generation,evolution of oxides on both the surface and interior of the powder,as well as the type of oxide nanoparticles in the fabricated ODS alloy.It is found that an iron oxide layer is formed on the surface of the powder during low temperature oxidation.And the iron oxide layer would be decomposed after thermal treatment at high temperature.In the consolidation process,the oxygen required by the reaction of alumina and yttrium oxide to produce nano scale Y-Al-O particles mainly derives from the decomposition of iron oxide layer at elevated temperature and the inward diffusion of oxygen.Using the direct oxidation process,YAlO_(3) nanoparticles are dispersed in the grains and at the grain boundaries of Fe-Cr-Al ODS alloy.展开更多
This is a paper for the sub-solidus phase relationships in the full system Si_3N_4-A1NAl_2O_3-SiO_2-Y_2O_3-YN. Within this system there exist seventy-six compatibility tetrahedra.
Dense Y-TZP ceramics and Y-TZP/Al_2O_3 composite ceramics are prepared successfully by microwave sintering using rectangle single mode (TE_(10n)) applicator. The heating characteristcs by microwave of the materials ar...Dense Y-TZP ceramics and Y-TZP/Al_2O_3 composite ceramics are prepared successfully by microwave sintering using rectangle single mode (TE_(10n)) applicator. The heating characteristcs by microwave of the materials are related to the sample compositions. Higher Y-TZP content leads to a higher heating-up rate and a shorter time period needed for heating-up. The input power, short circuit plug position and the opening size of adjustable coupling iris are adjusted timely to maintain the resonance and the optimum coupling condition, and therefore a certain heating-up rate and final stable sintering temperature could be achieved. Relative densities above 98% TD are obtained for Y-TZP and 20 Vol% Al_2O_3-Y-TZP composite ceramics, with their grain sizes of about 0.4 and 1.0 μm, respectively. It is also found that the sample center can be over-sintered when the temperature is too high since a higher temperature at the sample center is usually reached than that at the surface.展开更多
基金supported by the National Defense Science and Technology Industry Nuclear Material Technology Innovation Center Project(No.ICNM-2020-ZH-17)。
文摘This study presents the fabrication of 14CrFe-Cr-Al oxide dispersion strengthened(ODS)alloy by a direct oxidation process.In order to explain how oxide nanoparticles are formed in the consolidation process,the powders after oxidation are subjected to vacuum thermal treatment at high temperatures.Differential scanning calorimeter,X-ray photoelectron spectroscopy,scanning electron microscopy and transmission electron microscopy techniques are used to detect the generation,evolution of oxides on both the surface and interior of the powder,as well as the type of oxide nanoparticles in the fabricated ODS alloy.It is found that an iron oxide layer is formed on the surface of the powder during low temperature oxidation.And the iron oxide layer would be decomposed after thermal treatment at high temperature.In the consolidation process,the oxygen required by the reaction of alumina and yttrium oxide to produce nano scale Y-Al-O particles mainly derives from the decomposition of iron oxide layer at elevated temperature and the inward diffusion of oxygen.Using the direct oxidation process,YAlO_(3) nanoparticles are dispersed in the grains and at the grain boundaries of Fe-Cr-Al ODS alloy.
基金Materials Science and Engineering Department, The University of Michigan, U. S. A
文摘This is a paper for the sub-solidus phase relationships in the full system Si_3N_4-A1NAl_2O_3-SiO_2-Y_2O_3-YN. Within this system there exist seventy-six compatibility tetrahedra.
文摘Dense Y-TZP ceramics and Y-TZP/Al_2O_3 composite ceramics are prepared successfully by microwave sintering using rectangle single mode (TE_(10n)) applicator. The heating characteristcs by microwave of the materials are related to the sample compositions. Higher Y-TZP content leads to a higher heating-up rate and a shorter time period needed for heating-up. The input power, short circuit plug position and the opening size of adjustable coupling iris are adjusted timely to maintain the resonance and the optimum coupling condition, and therefore a certain heating-up rate and final stable sintering temperature could be achieved. Relative densities above 98% TD are obtained for Y-TZP and 20 Vol% Al_2O_3-Y-TZP composite ceramics, with their grain sizes of about 0.4 and 1.0 μm, respectively. It is also found that the sample center can be over-sintered when the temperature is too high since a higher temperature at the sample center is usually reached than that at the surface.
