Fuxing YIN
,
Y. Ohsawa and A.Sato (National Research Institute for Metals
,
Tsukuba
,
Ibaraki 305-0047
,
Japan)K.Aawahara(B.B.Materia Co. Ltd.
,
Chiba-Shi
,
Chiba 267-0066
,
Japan)
材料科学技术（英文）
A high damping condition is easily obtained in Mn-(16~24)Cu-(4~6)Ni-2Fe (at. pct) alloys,when cooling rate is controlled after the solid solution treatment at 1173 K. It is observed that the temperature dependent changes of Iogarithmic decrement in 10 h cooled samples are sensitive to the alloy composition. As compared with water quenching treatment, controlled 10 h cooling improves TN temperature of the alloys extensively by producing a Mn-enriched matrix portion in the alloys. Calcuiations suggest that the relative decreases of Cu and Ni content in the matrix portion be dominated by the Ni content in the original alloys, and therefore, the volume fraction of the Cu, Ni-enriched precipitates is estimated to be about 20% and 10% in the 4Ni and 6Ni alloys, respectively. As a result, the TN temperature fOr each alloy, corresponding to the rising temperature of logarithmic decrement, has been related to the Cu, and Ni content in the Mnenriched matrix. The existence of {110} twinning boundaries is confirmed in the microstructure of both 4Ni and 6Ni alloys. However, the relative lattice strains, which the twinning boundaries act to accommodate, are found largely different in the two alloys. It is considered that boundaries with smaller orientation deviation could coordinate the external Stresses easily by cyclic moving, and therefore, the broader damping peak which occurs in the 10 h cooled 6Ni alloy becomes feasible. Electron diffraction results also indicate possible for mation of many sub-crystals in the matrix phase, which are relatively rotated on some invariant planes. Those sub-crystal boundaries might play some attenuation roles in the temperature range between TN and room temperature.
关键词:
Feifei LI
,
Xiufeng HAN
,
Lixian JIANG
材料科学技术（英文）
Single barrier magnetic-tunnel-junctions (MTJs) with the layer structure of Ta(5)/Cu(30)/Ta(5)/Ni79Fe21(5)/Ir22Mn78(12)/Co60Fe20B20(4)/Al(0.8)-oxide/Co60Fe20B20(4)/Cu(30)/Ta(5) [thickness unit: nm] using the amorphous Co60Fe20B20 alloy as free and pinned layers were micro-fabricated. The experimental investigations showed that the tunnel magnetoresistance (TMR) ratio and the resistance decrease with increasing dc bias voltage from 0 to 500~mV or with increasing temperature from 4.2 K to RT. A high TMR ratio of 86.2% at 4.2 K, which corresponds to the high spin polarization of Co60Fe20B20 55%, was observed in the MTJs after annealing at 270℃ for 1 h. High TMR ratio of 53.1%, low junction resistance-area product RS of 3.56 kΩμm2, small coercivity Hc of ≤4 Oe, and relatively large bias-voltage-at-half-maximum TMR with the value V1/2 of greater than 570 mV at RT have been achieved in such Co-Fe-B MTJs.
关键词:
Tunnel magnetoresistance
,
null
,
null
,
null
,
null
Intermetallics
A new ferromagnetic Co-Fe-Hf-Ti-Mo-B bulk metallic glass was produced by copper mould casting method, using industrial raw materials. The magnetic properties were studied with the high-performance hysteresis loop tracer. The low coercivity, as low as 2 A/m for the as-cast sample, was found in the Co-Fe-based metallic glass rod with a diameter of 1.5 mm, the saturation magnetization is 0.6 T. The thermal stability was characterized by differential thermal analysis, X-ray diffraction was used to confirm the amorphous state of as-cast alloy and to perform the structural analysis of crystallization products. Crystallization temperature exceeding 900 K and supercooled liquid region of 35 K were found in the investigated glass. The high glass forming ability was explained by the slow nucleation rate of intermetallic compounds which are structurally complex in multicomponent system during solidification. High crystallization temperature suggests that the studied bulk metallic glass could be used as high-temperature soft magnetic material. (c) 2006 Elsevier Ltd. All rights reserved.
关键词:
glasses, metallic;thermal stability;rapid solidification processing;calorimetry;magnetic applications;supercooled liquid region;amorphous-alloys;ferromagnetic glasses;ni;transition;system
Journal of Alloys and Compounds
The isothermal section at 700 degrees C in the Co-rich ternary Sm-Co-B system was determined by means of X-ray diffraction. In this range, nine ternary borides were observed: Sm3Co13B2, SmCo4B, Sm3Co11B4, Sm2Co7B3, SmCo3B2, Sm2Co14B, SmCo12B6, SmCo4B4, SmCo2B2. The first five borides are members of the homologous series Smm + nCo5m + 3nB2n formed by alternative stacking m layers of SmCo5 with n layers of SmCo3B2 along the c-axis. The compound Sm3Co13B2 was not reported in previous isothermal sections found in the literature. (C) 2000 Elsevier Science S.A. All rights reserved.
关键词:
Sm-Co-B;phase diagram;magnetic-properties
Journal of Alloys and Compounds
The isothermal section at 700 degrees C in the Go-rich ternary Gd-Co-B system was determined by means of x-ray diffraction. In this range, nine ternary borides were observed: Gd3Co13B2, GdCo4B, Gd3Co11B4, Gd(2)Go(7)B(3), GdCo3B2 Gd2Co14B, GdCo12B6, GdCo4B4, GdGo(2)B(2). This isothermal section at 700 degrees C is similar to other isothermal sections found in the literatures, but they do not include the compounds Gd3Co13B2 and Gd2Co14B. The first five borides are members of the homologous series Gdm + nCo5m + 3nB2n, which is formed by alternative stacking of m layers of GdCo5 with n layers of GdCo3B2 along the c-axis. (C) 2000 Elsevier Science S.A. All rights reserved.
关键词:
Gd-Co-B;phase diagram;earth
Intermetallics
A new bulk metallic glass Fe56Co7Ni2Zr10Mo5B20 rod with a diameter of 1.5 mm was prepared by copper mould casting from industrial raw materials. The amorphous state and crystallization behaviour were investigated by X-ray diffraction. The thermal stability, such as the glass transition temperature (T-g), the onset temperature of crystallization (T-x), supercooled liquid region (DeltaT(x)) between T-g and T-x, and reduced glass temperature T-rg(T-g/T-m), the ratio of the glass transition temperature (T-g) and the onset temperature of melting (T-m) were measured by differential scanning calorimetry to be 868, 937, 69 K and 0.596, respectively. The crystallization products are determined to be alpha-Fe, ZrFe2, Fe3B, MoB2, and Mo2FeB2 and an unknown phase, as determined by X-ray analysis of the sample annealed for 1.5 ks at 973 K. This bulk metallic alloy exhibits ferromagnetic properties with saturation magnetization (M-s) of 41.6 emu/g, and low coercivity for the as-cast rod of 1.5 mm diameter. (C) 2004 Elsevier Ltd. All rights reserved.
关键词:
glasses;metallic;magnetic properties;thermal stability;high saturation magnetization;ferromagnetic glasses;supercooled;liquid;amorphous-alloys;forming ability;1.5 t;system;strength
曾英
,
唐明林
,
殷辉安
应用化学
doi:10.3969/j.issn.1000-0518.2001.10.007
采用三元体系的溶解度数据,运用多元线性回归法拟合了Li 2CO3(a),Na 2CO3(b),Li 2B4O7(c)的单盐参数、溶解平衡常数及有关的混合离子作用参数.它们的值分别为:β(o)a=-1.235 5,β(1)a=-2.654 6,Cφa=-0.004 660 7,β(0)b=-3.030 6,β(1)b=-3.023 8,Cφb=-0.290 89,β(0)c=-0.293 04,β(1)c=2.155 6,Cφc=-0.004 256 0,θLi,Na=1.041 8,θB.C=-2.630 5,ψLi,Na,C=-0.063 91,ψLi,Na,B=0.493 56,ψLi,B,C=-0.478 42,ΨNa,B,c=0.306 16,In K(Li2CO 3)=-8.962 9,In K(Na2CO3@10H2O)=3.064 6,ln K(Li2B4O 7@3H2O)=-7.356 6,ln K(Na2B4O7@10H2O)=-7.477 8.以盐的溶解平衡常数为判据,运用Pitzer方程计算了四元体系Li+,Na+//CO2-3,B4O2-7-H2O 298 K时的溶解度,并采用等温溶解平衡法,对该体系298 K时溶解度进行了实验测定,同计算值相比,二者基本吻合.
关键词:
Li+
,
Na+//CO2-3
,
B4O2-7-H2O体系
,
溶解度
,
预测
Journal of Applied Physics
The magnetic properties of R2Co14B1-xCx (x=0, 0.5 and R=Y, Sm) compounds have been studied by measuring the temperature dependence of the easy- and hard-magnetization curves on magnetically aligned samples between 1.5 and 300 K for Y2Co14(B,C) and at 4.2 K for Sm2Co14(B,C). The magnetic anisotropy of Y2Co14B increases due to the substitution of C for B, whereas the saturation magnetization decreases. Between 1.5 and 300 K, the anisotropy field of Y2Co14B0.5C0.5 increases about 2 T and the Co moment decreases about 0.05mu(B). The anisotropy field Of Sm2Co14B also increases upon C substitution and the saturation magnetization decreases slightly. The ac susceptibilities of both SM2Co14B and Sm2Co14B0.5C0.5 exhibit anomalies that may arise from a spin reorientation within the basal plane.
关键词:
nd2fe14b;exchange;nd2co14b;r2fe14b;field
Journal of Physics D-Applied Physics
Effects of B addition on the structure and magnetoresistance of as-quenched and annealed Co-Cu granular alloys have been studied. The formation of the Co2B phase reduces the number of small magnetic particles, which are the centres for spin-dependent scattering. The magnetoresistance of Co-Cu-B granular ribbons decreases with increasing B content.
关键词:
alloys;films
王莉萍
,
吴玉程
,
李云
,
张勇
,
李广海
电镀与精饰
doi:10.3969/j.issn.1001-3849.2004.06.001
利用化学镀的方法,以硫酸钴为主盐,二甲基胺硼烷为还原剂,制备纳米晶Co-B合金,研究了在各种条件下沉积速率的变化.结果表明合适的工艺参数的选择,可得到较好的沉积速率,并可由此得到一个化学镀Co-B合金纳米晶的较优配方参数.
关键词:
化学镀
,
Co-B合金
,
纳米晶
,
沉积速率
