A quench-treatment technique is used to prepare a high-quality polycrystalline sample of double perovskite Sr2FeMo06 （SFMO）. X-ray powder diffraction analysis reveals that the sample has a single phase and exhibits ...A quench-treatment technique is used to prepare a high-quality polycrystalline sample of double perovskite Sr2FeMo06 （SFMO）. X-ray powder diffraction analysis reveals that the sample has a single phase and exhibits I4/m symmetry. The cation order η of the sample increases to 98.9（2）% from 94.2（3）%, which is prepared by the traditional sol-gel method. The initial magnetization isotherm of the sample is detected at 300 K. Unit-cell magnetization for the current sample is 1.332 #s at 300 K, and the one for the traditional sol-gel method sample is 0.946#9. Unit-cell magnetization is enhanced to 40.80% by the quench-treatment technique. Quench treatment is an effective method of enhancing the Fe/Mo order and magnetic properties of double perovskite SFMO.展开更多
Both the band filling effect and Fe/Mo disorder have a close correlation with the physical properties of the double perovskite Ca2FeMoO6. Two series of Ca2FeMoO6and Nd0.3Ca1.7FeMoO6ceramics sintered at(1050℃, 1200℃,...Both the band filling effect and Fe/Mo disorder have a close correlation with the physical properties of the double perovskite Ca2FeMoO6. Two series of Ca2FeMoO6and Nd0.3Ca1.7FeMoO6ceramics sintered at(1050℃, 1200℃, and 1300℃) were specially designed to comparatively investigate the band-filling effect and Fe/Mo disorder on the physical properties of Ca2FeMoO6. The x-ray diffraction indicates that Fe/Mo disorder is sensitive to the sintering temperature. The magnetization behavior is mainly controlled by the Fe/Mo disorder not by the band filling effect, manifested by a close correlation of saturated magnetization(Ms) with the Fe/Mo disorder. Interestingly, magnetoresistance(MR) property of the same composition is dominantly contributed by the grain boundary strength, which can be expressed by the macroscopic resistivity values. However, the band filling effect caused by the Nd-substitution can decrease the spin polarization, and thus suppress the MR performance fundamentally. Contrary to the MR response, the Curie temperature(TC) shows an obvious optimization due to the band filling effect, which increases the carrier density near the Fermi level responsible for the ferromagnetic coupling interaction strengthen. Maybe, our work can provoke further research interests into the correlation of the band-filling effects and Fe/Mo disorder with the physical properties of other Fe/Mo-based double perovskites.展开更多
A series of AlCoCrFe_(1−x)NiMo_(x)high-entropy alloys(HEAs)were fabricated and characterized by XRD,SEM,EDS mapping,compression test,hardness and electrochemistry measurements.The research results indicate that after ...A series of AlCoCrFe_(1−x)NiMo_(x)high-entropy alloys(HEAs)were fabricated and characterized by XRD,SEM,EDS mapping,compression test,hardness and electrochemistry measurements.The research results indicate that after Mo completely replaces Fe,the compressive strength of the alloys can reach 3181 MPa because the addition of Mo can formσphase beneficial to the grain refinement,thereby improving the strength of the alloys.However,the addition of Mo has a detrimental effect on corrosion resistance as a result of formation of galvanic cell between the substrate andσphases.Although most of AlCoCrFe_(1−x)NiMo_(x)have lower corrosion current densities than pristine alloy,a partial Mo substitution(x=0.25)widens the passivation region of HEAs.The inconsistency of mechanical properties with corrosion resistance is ascribed to different roles of Mo in phase formation and protection of passive film.展开更多
为满足刀具、模具和耐磨件等工具领域的需要,研制了新型TiB2基硬质合金.在TiB2 Fe Mo硬质合金中,利用常规硬质合金生产工艺,研究不同含量的VC对合金晶粒度和性能的影响.与未添加VC的试样相比,添加0.5%VC后,合金中超细TiB2晶粒由38.94%...为满足刀具、模具和耐磨件等工具领域的需要,研制了新型TiB2基硬质合金.在TiB2 Fe Mo硬质合金中,利用常规硬质合金生产工艺,研究不同含量的VC对合金晶粒度和性能的影响.与未添加VC的试样相比,添加0.5%VC后,合金中超细TiB2晶粒由38.94%增加到59.39%;耐磨性提高了53.8%,抗氧化性提高了60%,800℃下抗弯强度比室温抗弯强度仅下降7.3%.表明适量添加VC可以使TiB2 Fe Mo硬质合金的耐磨性、高温强度和高温抗氧化性得到改善;可有效抑制晶粒长大,使硬质相颗粒均匀细化.展开更多
The ductility of TiAl intermetallics can be improved through stabilizing the ductile β phase.New β-stabilized Ti-45Al-xFe-yMo（x,y=1,2,3,4） alloys were designed through adding the β stabilizing elements Fe and Mo....The ductility of TiAl intermetallics can be improved through stabilizing the ductile β phase.New β-stabilized Ti-45Al-xFe-yMo（x,y=1,2,3,4） alloys were designed through adding the β stabilizing elements Fe and Mo.The microstructural evolution and deformation behavior of the Ti-45Al-xFe-yMo alloys were investigated.The results show that the amount of β（B2） phase is increased with the increase of alloying elements.Mo shows a higher capability for stabilizing the β phase than Fe.In the optimized Ti-45Al-3Fe-2Mo alloy,the grains are significantly refined to about 12 μm,and this alloy shows a very good hot ductility at the elevated temperature.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No U1304110the Doctoral Science Foundation of Henan Normal University under Grant No 01026500109
文摘A quench-treatment technique is used to prepare a high-quality polycrystalline sample of double perovskite Sr2FeMo06 （SFMO）. X-ray powder diffraction analysis reveals that the sample has a single phase and exhibits I4/m symmetry. The cation order η of the sample increases to 98.9（2）% from 94.2（3）%, which is prepared by the traditional sol-gel method. The initial magnetization isotherm of the sample is detected at 300 K. Unit-cell magnetization for the current sample is 1.332 #s at 300 K, and the one for the traditional sol-gel method sample is 0.946#9. Unit-cell magnetization is enhanced to 40.80% by the quench-treatment technique. Quench treatment is an effective method of enhancing the Fe/Mo order and magnetic properties of double perovskite SFMO.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1504107)the Doctoral Scientific Research Foundation(Grant No.qd15214)
文摘Both the band filling effect and Fe/Mo disorder have a close correlation with the physical properties of the double perovskite Ca2FeMoO6. Two series of Ca2FeMoO6and Nd0.3Ca1.7FeMoO6ceramics sintered at(1050℃, 1200℃, and 1300℃) were specially designed to comparatively investigate the band-filling effect and Fe/Mo disorder on the physical properties of Ca2FeMoO6. The x-ray diffraction indicates that Fe/Mo disorder is sensitive to the sintering temperature. The magnetization behavior is mainly controlled by the Fe/Mo disorder not by the band filling effect, manifested by a close correlation of saturated magnetization(Ms) with the Fe/Mo disorder. Interestingly, magnetoresistance(MR) property of the same composition is dominantly contributed by the grain boundary strength, which can be expressed by the macroscopic resistivity values. However, the band filling effect caused by the Nd-substitution can decrease the spin polarization, and thus suppress the MR performance fundamentally. Contrary to the MR response, the Curie temperature(TC) shows an obvious optimization due to the band filling effect, which increases the carrier density near the Fermi level responsible for the ferromagnetic coupling interaction strengthen. Maybe, our work can provoke further research interests into the correlation of the band-filling effects and Fe/Mo disorder with the physical properties of other Fe/Mo-based double perovskites.
基金supported by Suqian Sci&Tech Program Foundation,China(No.K202130)the National Natural Science Foundation of China(No.52071176)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China.
文摘A series of AlCoCrFe_(1−x)NiMo_(x)high-entropy alloys(HEAs)were fabricated and characterized by XRD,SEM,EDS mapping,compression test,hardness and electrochemistry measurements.The research results indicate that after Mo completely replaces Fe,the compressive strength of the alloys can reach 3181 MPa because the addition of Mo can formσphase beneficial to the grain refinement,thereby improving the strength of the alloys.However,the addition of Mo has a detrimental effect on corrosion resistance as a result of formation of galvanic cell between the substrate andσphases.Although most of AlCoCrFe_(1−x)NiMo_(x)have lower corrosion current densities than pristine alloy,a partial Mo substitution(x=0.25)widens the passivation region of HEAs.The inconsistency of mechanical properties with corrosion resistance is ascribed to different roles of Mo in phase formation and protection of passive film.
文摘为满足刀具、模具和耐磨件等工具领域的需要,研制了新型TiB2基硬质合金.在TiB2 Fe Mo硬质合金中,利用常规硬质合金生产工艺,研究不同含量的VC对合金晶粒度和性能的影响.与未添加VC的试样相比,添加0.5%VC后,合金中超细TiB2晶粒由38.94%增加到59.39%;耐磨性提高了53.8%,抗氧化性提高了60%,800℃下抗弯强度比室温抗弯强度仅下降7.3%.表明适量添加VC可以使TiB2 Fe Mo硬质合金的耐磨性、高温强度和高温抗氧化性得到改善;可有效抑制晶粒长大,使硬质相颗粒均匀细化.
基金Project(2011CB605505) supported by the National Basic Research Program of ChinaProject(2011JQ002) supported by the Fundamental Research Funds for the Central Universities,ChinaProject supported by the Open-End Fund for the Valuable and Precision Instruments of Cental South University,China
文摘The ductility of TiAl intermetallics can be improved through stabilizing the ductile β phase.New β-stabilized Ti-45Al-xFe-yMo（x,y=1,2,3,4） alloys were designed through adding the β stabilizing elements Fe and Mo.The microstructural evolution and deformation behavior of the Ti-45Al-xFe-yMo alloys were investigated.The results show that the amount of β（B2） phase is increased with the increase of alloying elements.Mo shows a higher capability for stabilizing the β phase than Fe.In the optimized Ti-45Al-3Fe-2Mo alloy,the grains are significantly refined to about 12 μm,and this alloy shows a very good hot ductility at the elevated temperature.
