The segregation (distribution) of nickel and the composition of its constituents influence the low thermal expansion characteristics (Invar effect) in Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy. The change of coefficient of the thermal expansion and magnetic properties were studied as an aspect of carbon addition causing the segregation of Ni in primary austenite of as-cast Fe-30 wt.% Ni-12.5 wt.% Co Invar alloy. The coefficient of thermal expansion of Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy showed its lowest value at 0.08 wt.% carbon, increased with increasing carbon content in the range of 0.08-1.0 wt.%C, kept constant at 1.0-2.0 wt.%C and decreased at carbon higher than 2.0 wt.%. The effective distribution of the coefficient of nickel in as-cast Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy increased with increasing carbon content. The volume fraction of the γ phase of Fe-30 wt.% Ni-12.5 wt.% Co-xC alloy increased with increasing carbon content. The microstructure of Fe-30 wt.% Ni-12.5 wt.% Co-xC alloy changed with the carbon content was independent of the coefficient of thermal expansion. The Curie temperature changed linearly with the carbon content and was similar to the change of the coefficient of thermal expansion. Moreover, the coefficient of thermal expansion decreased when the ratio of saturation magnetization to Curie temperature (σ s /T c ) increased, decreasing the Curie temperature and showed a specific relationship with the magnetic properties of the Fe-30 wt.% Ni-12.5 wt.% Co-xC Invar alloy.

The effects of deformation on 2nd recrystallization behavior with or without magnetic field for a 1st recrystallized electrical steel sheet have been investigated. Annealing temperatures (800, 1000 o C) and cold-rolling rates (50, 70 %) were experimental parameters. A magnetic field of 5 T using a superconducting magnet at a heating rate of 15 o C/min was applied in a direction parallel to the rolling direction. The intensity of α-fiber was increased due to the deformation and, in particular, the formation of {100}<110> component was tremendous. Considerable formation of {001}<100> component was also found. At 800 o C, α-fiber was developed rapidly due to deformation, and η-fiber was also formed in the components {100}<100> and {110}<100>. The effect of magnetic field annealing was more significant at 800 o C, while the effect at 1000 o C was negligible. These results are discussed in a phenomenological context considering the atomic fluctuation and magnetic induction depending on annealing temperature and magnetic field.

Sputter-quenched SiO2 films containing Pb, which is insoluble to SiO2, have been found to exhibit a remarkably enhanced upper critical field (H~), which is about 90 times higher than that of pure Pb. The sputtered films consisted of an amorphous SiO: matrix and fcc Pb particles, dispersed homogeneously in the amorphous matrix. The particle sizes and interparticle distances were about 5 to 350 nm and 5 to 50 nm, respectively. The superconducting transition temperature (To), upper critical magnetic field (H,2) at 4.2 K, and residual resistivity (13,0) at 10 K were 7.05 K, 4.37 T and 1.4x10 ~" ~,Qm for (SiO2)29PbTl(VOl.%), respectively. Since the l,g evaluated from linearized Ginzburg-Landau equation was 0.524 nm for x=71%, while theof pure Pb at 4.2 K was valued at 2.3x10 ~ nm, it can be concluded that the l,~ of these SiO2-Pb films was drastically reduced owing to the refinement of Pb particles and internal defects (stress) induced by vapor quenching. Therefore the high field superconductivity can be interpreted mainly due to the significant decrease of coherence length, resulting from the large reduction of the effective mean free path length (l,.~) of electrons. The dual phase microstructure also had influence on the increase of the fluxoid pinning force and behaved like a type-II superconductor.Key words : insoluble system, upper critical field, coherence length, mean free path length, interface, type-I1 superconductor TRODUCTIONDuring the last several years, Inoue et al. have performed a series of studies [1-8] on preparation of the duplex structure alloys with finely and homogeneously dispersed immiscible phase particles, by taking advantage of the phase-separation phenomena in equilibrium solid and/or liquid states. They have found [3,4,[6][7][8] that rapidly quenched Ge-Pb, Ge-Pb-Bi and Ge-Pb-Bi-Sn alloys consisting of fcc Pb, hcp e (Pb-Bi) or e+bct Sn+hexagonal Bi particles embedded in cubic Ge matrix, and exhibiting unique magnetic and electrical properties, i.e. upper critical magnetic field 10 times or more higher than that of pure Pb [9] or e-Pb~0Bi,0 [ 10] alloy, and with an extremely high electrical resistivity of 7,000 to 10,000 ~Om at 250 K combined with a positive and linear temperature variation as large as about 70 to 90% in the range from 10 to 273 K. These anomalous electrical properties have been attributed to the duplex structures composed of a semiconductor and a metal. This new information suggests the possibility that other types of duplex structure alloys, consisting of superconducting metallic pfiases embedded in an oxide or a nitride matrix, also may exhibit electrical properties with more enhanced anomaly, because the difference in electrical properties between an oxide (or a nitride) and a metal is more significant than that between a semiconductor and a metal.The purpose of the present study is to examine the microstructures and superconducting properties of sputtered SiO2-Pb films, and to investigate the fitness of the general concept derived from pervious results [3,4,[6][7][8] on...

Electric conducting behavior, sectional residual stress and texture in deformed Al-Zr alloy were investigated in order to investigate effect of deformation on electric conductance. {111} textures were developed in the wire of deformed Al-Zr alloy and most strong intensity of {111} texture was observed at the core in the cross section of the wire. Residual stress was mainly measured at the surface and , especially, measured at the core in the case of 4.5Φ wire, also, electric conductance was higher at the surface than at the core. This means that electric conductance might be affected by distribution of the residual stress.

As a way to expand electric capacity in power line with hovering of electric power demand, STACIR/AW (super thermal-resistant Al alloy conductors Al-clad Invar-reinforced) overhead conductor which cans double ampacity has been developed. The STACIR/AW power line is mechanically composite stranded wire composed of INVAR/AW stranded wire as core for sag control and heat-resistant aluminum alloy for delivering doubled electric current. Recently, in order to ensure stable line operation and to predict its span of life, the changes of thermal properties for STACIR/AW have been investigated. In the present work, the changes of strain with temperature and the creep behavior as important factors in sag control will be presented. The transition temperature of STACIR/AW 410sqmm was estimated approximately 130°C and the creep rates were decreased with temperatures.