In this article, the quenched Nd_4.5Fe_75Co_1Si_l B_18.5 ribbons were prepared, and the structures and properties were investigated. The results show that the change of structures of Nd_4.5 Fe_75 Co_1 Si_1 B_18.5 qu...In this article, the quenched Nd_4.5Fe_75Co_1Si_l B_18.5 ribbons were prepared, and the structures and properties were investigated. The results show that the change of structures of Nd_4.5 Fe_75 Co_1 Si_1 B_18.5 quenched amorphous ribbons is Am→Am'+Fe_3B+Nd_2Fe_23B_3+Nd_2Fe_14B→Nd_2- Fe_14B when it is heated. The effect of crystallizing treatment temperature and time on the magnetic properties of the quenched alloy was studied. The magnetic properties of 16 m/s quenched ribbons for 710℃×1200 s crystallizing treatment reach _iH_c=238.6 hA/m, B_r=0.8987 T and (BH)max=51.39 kJ/m^3. The grain size is about DFe3=32 nm and DNd2Fe14B=22 nm.展开更多
The creep behaviour of β-Si3N4 whisker reinforced Al-8.5Fe-1.3V-1.7Si composite has been investigated at the temperature 773 and 823 K. The results are characterized by high stress exponent and high apparent creep ac...The creep behaviour of β-Si3N4 whisker reinforced Al-8.5Fe-1.3V-1.7Si composite has been investigated at the temperature 773 and 823 K. The results are characterized by high stress exponent and high apparent creep activation energy The creep data can be interpreted based on the incorporation of a threshold Stress and a load transfer coefficient into the power-law creep equation. A good correlation between the normalized creep rate and normalized effective stress is available which demonstrates that the creep behaviour of both the alloy and the composite is controlled by the matrix lattice self-diffusion in AI. EXamination on microstructure shows that edge dislocations exist at the interfaces between two adjacent whiskers and the intedeces emit edge dislocations in parallel paired-columns.展开更多
A metallic crystalline/amorphous （c/a） bulk composite was prepared by the slow cooling method after remelting the amorphous Fe78Si9B13 ribbon. By X-ray diffraction （XRD）, differential scanning calorimetry （DSC） ...A metallic crystalline/amorphous （c/a） bulk composite was prepared by the slow cooling method after remelting the amorphous Fe78Si9B13 ribbon. By X-ray diffraction （XRD）, differential scanning calorimetry （DSC） and scanning electron microscope （SEM）, the composite consists of the primary dendrite α-Ee （without Si） as well as the amorphous matrix. After being anneal at 800 K, the uniform spheroid particles are formed in the c/a composite, which does not form in the amorphous ribbon under the various annealing process. Energy dispersive analysis of X-rays （EDAX）, SEM and XRD were applied to give more detailed information. The formation and evolution of the particle may stimulate the possible application of the Fe-matrix amorphous alloy.展开更多
为有效提升吸波材料的电磁吸收强度和有效吸收带宽,采用球磨法对球状Fe-Si-Cr进行扁平化处理,通过机械共混法将不同形貌Fe-Si-Cr和羰基铁粉(Carbonyl iron powder,CIP)复合,研究不同质量比对复合材料电磁参数和微波吸收性能的影响。实...为有效提升吸波材料的电磁吸收强度和有效吸收带宽,采用球磨法对球状Fe-Si-Cr进行扁平化处理,通过机械共混法将不同形貌Fe-Si-Cr和羰基铁粉(Carbonyl iron powder,CIP)复合,研究不同质量比对复合材料电磁参数和微波吸收性能的影响。实验结果表明,大长径比可以提高材料的介电常数和磁导率,并使反射率峰值向低频移动。片状Fe-Si-Cr和CIP的低频吸波性能优于球形粒子。实验制备的复合材料中,样品I的最大反射损耗为-45.92 dB,有效吸收带宽为1.5 GHz。样品L的最大反射损耗为-22.11 dB,有效吸收带宽大于6.2 GHz。吸波剂的形貌对材料的电磁吸收性能有显著影响。将不同形貌的CIP和Fe-Si-Cr按不同配比复合后,可以得到不同频率下性能优良的吸波体。利用阻抗匹配函数可以从理论上预测出反射损耗峰值对应的吸波剂厚度和频率。双层吸波材料相比于单层吸波材料,其有效吸收带宽更大,可以通过改变匹配层、吸收层的厚度来获得不同频率下吸波性能优良的吸波体,更易满足新型吸波材料“薄、轻、宽、强”的要求。展开更多
基金Commission of Science and Technology of Province Liaoning !(No.962154).
文摘In this article, the quenched Nd_4.5Fe_75Co_1Si_l B_18.5 ribbons were prepared, and the structures and properties were investigated. The results show that the change of structures of Nd_4.5 Fe_75 Co_1 Si_1 B_18.5 quenched amorphous ribbons is Am→Am'+Fe_3B+Nd_2Fe_23B_3+Nd_2Fe_14B→Nd_2- Fe_14B when it is heated. The effect of crystallizing treatment temperature and time on the magnetic properties of the quenched alloy was studied. The magnetic properties of 16 m/s quenched ribbons for 710℃×1200 s crystallizing treatment reach _iH_c=238.6 hA/m, B_r=0.8987 T and (BH)max=51.39 kJ/m^3. The grain size is about DFe3=32 nm and DNd2Fe14B=22 nm.
文摘The creep behaviour of β-Si3N4 whisker reinforced Al-8.5Fe-1.3V-1.7Si composite has been investigated at the temperature 773 and 823 K. The results are characterized by high stress exponent and high apparent creep activation energy The creep data can be interpreted based on the incorporation of a threshold Stress and a load transfer coefficient into the power-law creep equation. A good correlation between the normalized creep rate and normalized effective stress is available which demonstrates that the creep behaviour of both the alloy and the composite is controlled by the matrix lattice self-diffusion in AI. EXamination on microstructure shows that edge dislocations exist at the interfaces between two adjacent whiskers and the intedeces emit edge dislocations in parallel paired-columns.
基金the National Natural Science Foundation of China(No. 50871061 and 50471052)the Shandong Science and Research Foundation (No. Y2005F02)+1 种基金the Project for New Century Talent of Ministry of Education (No. NCET-06-584)Alexander von Humboldt Foundation
文摘A metallic crystalline/amorphous （c/a） bulk composite was prepared by the slow cooling method after remelting the amorphous Fe78Si9B13 ribbon. By X-ray diffraction （XRD）, differential scanning calorimetry （DSC） and scanning electron microscope （SEM）, the composite consists of the primary dendrite α-Ee （without Si） as well as the amorphous matrix. After being anneal at 800 K, the uniform spheroid particles are formed in the c/a composite, which does not form in the amorphous ribbon under the various annealing process. Energy dispersive analysis of X-rays （EDAX）, SEM and XRD were applied to give more detailed information. The formation and evolution of the particle may stimulate the possible application of the Fe-matrix amorphous alloy.
