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
Effect of different Mn and Mo contents on microstructure and mechanical properties of Al-Si-Cu-Mg-0.6Fe alloy was studied.Results indicate that the increase of Mo and decrease of Mn lead to a decrease in the size of ...Effect of different Mn and Mo contents on microstructure and mechanical properties of Al-Si-Cu-Mg-0.6Fe alloy was studied.Results indicate that the increase of Mo and decrease of Mn lead to a decrease in the size of theα-Al_(15)(FeMnMo)_(3)Si_(2) phase formed during solidification.Theα-Al_(15)(FeMnMo)_(3)Si_(2) phase reaches a minimum value of about 16.3μm at 0.2wt.%Mo and 0.1wt.%Mn addition.After solution treatment,theα-Al(FeMnMo)Si dispersed phase is precipitated.When only Mn is added,theα-Al(FeMnMo)Si dispersed phase mainly distributes near the grain boundaries,while when only Mo is added,it primarily distributes in the central region of the matrix.When both Mn and Mo are added,the dispersed phase has a larger and denser dispersed region and is uniformly distributed near the Al matrix and grain boundaries.Moreover,the best overall mechanical properties of the alloy are obtained with the combined addition of 0.1wt.%Mn and 0.2wt.%Mo,due to the smaller size ofα-Al_(15)(FeMnMo)_(3)Si_(2) phase and the larger area fraction and higher density of theα-Al(FeMnMo)Si dispersed phase.The yield strength,ultimate tensile strength,and elongation are respectively improved 67.7 MPa,48.5 MPa and 5.3%,respectively,compared to that of the alloy with only 0.3wt.%Mn.展开更多
TEM study was made to explore the mechanism of the strain-age hardening of initially-dis- ordered (Co_(78)Fe_(22))_3V,which was found to be attributed to the formation of a special disloca- tion-stacking fault configu...TEM study was made to explore the mechanism of the strain-age hardening of initially-dis- ordered (Co_(78)Fe_(22))_3V,which was found to be attributed to the formation of a special disloca- tion-stacking fault configuration in company with disorder-order transformation-disloca- tions extended to stacking faults on{111}planes and got connected with each other through partial dislocation reaction at intersections of{111}planes,leading to dense networks with cells bounded by stacking fault tetrahedrons.The results also indicated that ordered (Co_(78)Fe_(22))_3V has very low stacking fault energy on{111}planes and relative high and isotropie antiphase boundary energy,which implies that it is most likely to be Lomer-Cottrell locks,not Kear-Wilsdof locks,that are responsible for the high strength at high temperatures of this alloy.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
对应口腔环境中 p H值发生明显变化以及形成龋齿的自然现象 ,采用加速试验法研究了新型钛合金在不同 p H值乳酸中浸泡的耐腐蚀性能。研究表明当 p H=4即酸性略高于龋齿发病时酸性条件下 ,新型牙科钛合金能够完全耐乳酸腐蚀。在乳酸中腐...对应口腔环境中 p H值发生明显变化以及形成龋齿的自然现象 ,采用加速试验法研究了新型钛合金在不同 p H值乳酸中浸泡的耐腐蚀性能。研究表明当 p H=4即酸性略高于龋齿发病时酸性条件下 ,新型牙科钛合金能够完全耐乳酸腐蚀。在乳酸中腐蚀形式以点蚀为主 ,且随酸性增强有向晶间腐蚀转变的趋势。ICP分析表明合金在乳酸中的溶解析出物主要是 Fe,Fe的加入不利于合金的耐腐蚀性能。热力学计算表明设计的新型钛合金氧化膜含有 Mn2 O3、Nb2 O5、Zr O2 和 Ti O2 中的全部或部分 ,XPS分析表明氧化膜中的确含有 Mn2 O3、Nb2 O5和 Ti O2 ,主要是 Ti O2 。这三种氧化物致密且 Ti O2 和 Nb2 O5耐腐蚀 ,有利于合金的耐腐蚀性能。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
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This work was financially supported by the Key Research and Development Program of Shandong Province(No.2021SFGC1001)the National Natural Science Foundation of China(No.U1864209).
文摘Effect of different Mn and Mo contents on microstructure and mechanical properties of Al-Si-Cu-Mg-0.6Fe alloy was studied.Results indicate that the increase of Mo and decrease of Mn lead to a decrease in the size of theα-Al_(15)(FeMnMo)_(3)Si_(2) phase formed during solidification.Theα-Al_(15)(FeMnMo)_(3)Si_(2) phase reaches a minimum value of about 16.3μm at 0.2wt.%Mo and 0.1wt.%Mn addition.After solution treatment,theα-Al(FeMnMo)Si dispersed phase is precipitated.When only Mn is added,theα-Al(FeMnMo)Si dispersed phase mainly distributes near the grain boundaries,while when only Mo is added,it primarily distributes in the central region of the matrix.When both Mn and Mo are added,the dispersed phase has a larger and denser dispersed region and is uniformly distributed near the Al matrix and grain boundaries.Moreover,the best overall mechanical properties of the alloy are obtained with the combined addition of 0.1wt.%Mn and 0.2wt.%Mo,due to the smaller size ofα-Al_(15)(FeMnMo)_(3)Si_(2) phase and the larger area fraction and higher density of theα-Al(FeMnMo)Si dispersed phase.The yield strength,ultimate tensile strength,and elongation are respectively improved 67.7 MPa,48.5 MPa and 5.3%,respectively,compared to that of the alloy with only 0.3wt.%Mn.
文摘TEM study was made to explore the mechanism of the strain-age hardening of initially-dis- ordered (Co_(78)Fe_(22))_3V,which was found to be attributed to the formation of a special disloca- tion-stacking fault configuration in company with disorder-order transformation-disloca- tions extended to stacking faults on{111}planes and got connected with each other through partial dislocation reaction at intersections of{111}planes,leading to dense networks with cells bounded by stacking fault tetrahedrons.The results also indicated that ordered (Co_(78)Fe_(22))_3V has very low stacking fault energy on{111}planes and relative high and isotropie antiphase boundary energy,which implies that it is most likely to be Lomer-Cottrell locks,not Kear-Wilsdof locks,that are responsible for the high strength at high temperatures of this alloy.
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.
文摘对应口腔环境中 p H值发生明显变化以及形成龋齿的自然现象 ,采用加速试验法研究了新型钛合金在不同 p H值乳酸中浸泡的耐腐蚀性能。研究表明当 p H=4即酸性略高于龋齿发病时酸性条件下 ,新型牙科钛合金能够完全耐乳酸腐蚀。在乳酸中腐蚀形式以点蚀为主 ,且随酸性增强有向晶间腐蚀转变的趋势。ICP分析表明合金在乳酸中的溶解析出物主要是 Fe,Fe的加入不利于合金的耐腐蚀性能。热力学计算表明设计的新型钛合金氧化膜含有 Mn2 O3、Nb2 O5、Zr O2 和 Ti O2 中的全部或部分 ,XPS分析表明氧化膜中的确含有 Mn2 O3、Nb2 O5和 Ti O2 ,主要是 Ti O2 。这三种氧化物致密且 Ti O2 和 Nb2 O5耐腐蚀 ,有利于合金的耐腐蚀性能。
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.
