The microstructural evolution of nanocrystalline Cu-10%Nb(mass fraction) alloy during mechanical alloying(MA) was investigated by using X-ray diffraction,optical microscopy(OM),scanning electron microscopy(SEM) and tr...The microstructural evolution of nanocrystalline Cu-10%Nb(mass fraction) alloy during mechanical alloying(MA) was investigated by using X-ray diffraction,optical microscopy(OM),scanning electron microscopy(SEM) and transmission electron microscopy(TEM) observation. Upon milling of Cu-Nb powders with coarse grains,the grain size is found to decrease gradually with lengthening milling time,and reach the minimum value(about 9 nm) after 100 h milling. The microstrain and the microhardness of the powders increase during the grain refinement. And Cu lattice parameter increases steadily over 100 h milling. The mechanisms of solid solution extension during milling were discussed. The results show that up to 10%Nb can be brought into solid solution by MA. The extension of solid solution is found to relate closely with the formation of nanocrystalline.展开更多
Nowadays, most of nanocrystalline materials (NM) are fabricated from the gas phase by an evaporation/condensation process. However, this process is difficult to scale up. Recently, mechanical alloying has become an al...Nowadays, most of nanocrystalline materials (NM) are fabricated from the gas phase by an evaporation/condensation process. However, this process is difficult to scale up. Recently, mechanical alloying has become an alternative route to produce NM of commercial significance. This method, through low temperature solid state reaction, can produce novel phases and structures of alloys which would not be obtained by any other method, and hence, has attracted great attention.展开更多
FeCoN soft magnetic thin films are prepared by using the reactive direct-current magnetron sputtering technique. It is found that the addition of N2 can reduce the coercivity of the FeCoN film, and excellent soft magn...FeCoN soft magnetic thin films are prepared by using the reactive direct-current magnetron sputtering technique. It is found that the addition of N2 can reduce the coercivity of the FeCoN film, and excellent soft magnetic properties can be obtained when the ratio of N2 flow to total gas flow is 10%. The influences of texture, grain size, and stress on the magnetic properties and the high-frequency behaviors of the films are also discussed.展开更多
Amorphous and nanocrystalline (Fe1–xNix)81Nb7B12 (x = 0, 0.25, 0.5, 0.75) alloys were measured by M?ssbauer spectrometry in the weak external magnetic field of 0.5 T. From structural analyses, ferromagnetic bcc-FeNi ...Amorphous and nanocrystalline (Fe1–xNix)81Nb7B12 (x = 0, 0.25, 0.5, 0.75) alloys were measured by M?ssbauer spectrometry in the weak external magnetic field of 0.5 T. From structural analyses, ferromagnetic bcc-FeNi and fcc-FeNi and paramagnetic (Fe-Ni)23B6 phases were identified in the annealed samples. It was shown that in the external magnetic field the intensities of the 2nd and the 5th lines (A23 parameter) are the most sensitive M?ssbauer parameters. Rather small changes were observed in the values of internal magnetic field. Our results showed that the amorphous precursor is more sensitive to the influence of external magnetic field than the nanocrystalline alloy. All spectra of amorphous precursor showed the increase of A23 parameter and decrease of internal magnetic field values of about 1 T (±0.5 T) under influence of external magnetic field. In the case of nanocrystalline samples the tendency for the values of internal magnetic field is similar but the effect is not so pronounced. The measurements confirmed that even weak external magnetic field affected orientation of the net magnetic moments. Our results indicate that effect of the external magnetic field is stronger in the case of amorphous samples due to their disordered structure.展开更多
通过机械合金化制备了 Al-15%Pb-4%Si-1%Sn-1.5%Cu(质量分数)纳米晶粉末。采用 X 射线衍射(XRD),扫描电镜(SEM)和透射电镜(TEM)对不同球磨时间的混合粉末的组织结构、晶粒大小、微观形貌以及颗粒中化学成分分布情况进行了研究。结果表...通过机械合金化制备了 Al-15%Pb-4%Si-1%Sn-1.5%Cu(质量分数)纳米晶粉末。采用 X 射线衍射(XRD),扫描电镜(SEM)和透射电镜(TEM)对不同球磨时间的混合粉末的组织结构、晶粒大小、微观形貌以及颗粒中化学成分分布情况进行了研究。结果表明混合粉末经过球磨后形成了纳米晶,其组织非常均匀。球磨对 Pb 的作用效果明显大于对 Al 的作用效果,经过 40 h 球磨后 Pb 粒子达到 40 nm,而 Al 在球磨 60 h 后晶粒为 65 nm;经球磨后,Cu 和 Si 固溶于 Al 的晶格中,而 Sn 则固溶于 Pb 晶格中,并且 Al 和 Pb 发生了互溶,形成了 Pb(Al)超饱和固溶体;在球磨过程中硬度高的脆性粒子 Si 难于完全实现合金化。展开更多
基金Project(2006AA03Z517) supported by the National High-Tech Research and Development Program of China
文摘The microstructural evolution of nanocrystalline Cu-10%Nb(mass fraction) alloy during mechanical alloying(MA) was investigated by using X-ray diffraction,optical microscopy(OM),scanning electron microscopy(SEM) and transmission electron microscopy(TEM) observation. Upon milling of Cu-Nb powders with coarse grains,the grain size is found to decrease gradually with lengthening milling time,and reach the minimum value(about 9 nm) after 100 h milling. The microstrain and the microhardness of the powders increase during the grain refinement. And Cu lattice parameter increases steadily over 100 h milling. The mechanisms of solid solution extension during milling were discussed. The results show that up to 10%Nb can be brought into solid solution by MA. The extension of solid solution is found to relate closely with the formation of nanocrystalline.
基金Project supported by the National Natural Science Foundation of China
文摘Nowadays, most of nanocrystalline materials (NM) are fabricated from the gas phase by an evaporation/condensation process. However, this process is difficult to scale up. Recently, mechanical alloying has become an alternative route to produce NM of commercial significance. This method, through low temperature solid state reaction, can produce novel phases and structures of alloys which would not be obtained by any other method, and hence, has attracted great attention.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10874060 and 60803035)
文摘FeCoN soft magnetic thin films are prepared by using the reactive direct-current magnetron sputtering technique. It is found that the addition of N2 can reduce the coercivity of the FeCoN film, and excellent soft magnetic properties can be obtained when the ratio of N2 flow to total gas flow is 10%. The influences of texture, grain size, and stress on the magnetic properties and the high-frequency behaviors of the films are also discussed.
文摘Amorphous and nanocrystalline (Fe1–xNix)81Nb7B12 (x = 0, 0.25, 0.5, 0.75) alloys were measured by M?ssbauer spectrometry in the weak external magnetic field of 0.5 T. From structural analyses, ferromagnetic bcc-FeNi and fcc-FeNi and paramagnetic (Fe-Ni)23B6 phases were identified in the annealed samples. It was shown that in the external magnetic field the intensities of the 2nd and the 5th lines (A23 parameter) are the most sensitive M?ssbauer parameters. Rather small changes were observed in the values of internal magnetic field. Our results showed that the amorphous precursor is more sensitive to the influence of external magnetic field than the nanocrystalline alloy. All spectra of amorphous precursor showed the increase of A23 parameter and decrease of internal magnetic field values of about 1 T (±0.5 T) under influence of external magnetic field. In the case of nanocrystalline samples the tendency for the values of internal magnetic field is similar but the effect is not so pronounced. The measurements confirmed that even weak external magnetic field affected orientation of the net magnetic moments. Our results indicate that effect of the external magnetic field is stronger in the case of amorphous samples due to their disordered structure.
文摘通过机械合金化制备了 Al-15%Pb-4%Si-1%Sn-1.5%Cu(质量分数)纳米晶粉末。采用 X 射线衍射(XRD),扫描电镜(SEM)和透射电镜(TEM)对不同球磨时间的混合粉末的组织结构、晶粒大小、微观形貌以及颗粒中化学成分分布情况进行了研究。结果表明混合粉末经过球磨后形成了纳米晶,其组织非常均匀。球磨对 Pb 的作用效果明显大于对 Al 的作用效果,经过 40 h 球磨后 Pb 粒子达到 40 nm,而 Al 在球磨 60 h 后晶粒为 65 nm;经球磨后,Cu 和 Si 固溶于 Al 的晶格中,而 Sn 则固溶于 Pb 晶格中,并且 Al 和 Pb 发生了互溶,形成了 Pb(Al)超饱和固溶体;在球磨过程中硬度高的脆性粒子 Si 难于完全实现合金化。
