Β2 Phases Research Articles

18: Critical evaluation of constitution of cobalt-iron-silicon and iron-nickel-silicon alloys

The phase equilibria in the Co-Fe-Si and Fe-Ni-Si systems are reviewed in the light of available experimental data. The projection of the liquidus surface of the Co-Fe-Si system up to 35%Si contains five ternary invariant reactions (two eutectics and three other ternary transitions), and surfaces of primary crystallization for the phases αδFe, γFe, Fe2Si, β-Co2Si, α-Co2Si, α-Co2Si, and Co3Si. At higher Si contents a pseudo-binary eutectic section (experimental) between FeSi2 and CoSi2 suggests the existence of two ternary eutectic reactions and four primary surfaces corresponding to (Co, Fe)Si, FeSi2, CoSi2, and Si. For the solid state two experimental isothermal sections exist, at 1160°C (up to 25%Si) and at 800°C (over the whole composition range). In each case modifications have been introduced to achieve conformity with later work on the binary systems. The equilibria are well established and consistent with what is known of the liquid-solid equilibria. Experimental data for the liquid-solid equilibria in the Fe-Ni-Si system are too limited for the definition of an experimental projection. Detailed studies at 600°C show that a ternary cubic phase τ1 occurs at ~35% Ni, and comes into equilibrium with αδFe, γFe, Ni5Si2, and Ni2Si, and probably with the ordered bcc phases derived from the β1h and β2 phases of the Fe-Si system. Data for more Ni-rich alloys between 1000 and 450°C show that at the lowest of these temperatures ordered FeNi3 containing ~4%Si comes into equilibrium with Ni3Si containing ~7% Fe. Equilibria calculated thermodynamically at 1127 and 727°C are broadly consistent with the experimental isothermal sections. From available general information the nature of the liquid-solid equilibria may be suggested, interpreting the solid-state triangulations observed experimentally. These suggestions may be summarized by a hypothetical liquidus projection analogous to that recommended for the Co-Fe-Si system.

地震発生前の異常地殻変動継続時間とマグニチュードとの関係

Based on some examples of the vertical crustal movenent accompanied with earthquakes, the detailed phases of a cycle of seismic crustal movement are formulated as follows, α: steady state movementβ1: state of dilatancyβ2: unstable movement following β1 phaseγ1: pre-seismic slipγ2: co-seismic slipγ3: post-seismic slipδ: transient state movement.The crust is deformed lineary with time under tectonic stress field (α phase). After the accumulation of strain, the multiplication of cracks starts (β1 phase). The unstable and pulsative movement follows to the β1 phase (β2 phase). The β1 and β2 phases might correspond to the stress concentration around the future slip plane. Just before the earthquake, the pre-seismic slow slip may be caused on the fault plane (γ1 phase). At the time of earthquake, rapid slip on the fault plane emits the elastic waves(γ2 phase). Following the earthquake movement of β and γ phases, the transient phase may be caused under tectonic stress (δ phase).Analysing the selected eight examples of precursoy crustal movement, duration period of β1 and β2 phases, that is, the period from the start of anomalous crustal movement to the occurence of earthquake, are estimated. There exists a relation between the estimated duration period t and the magnitude of earthquakes M:logt(year)=0.52M-2.80.On the other hand, the equated radius r of anomalous crustal movement is expressed aslogr(km)=0.51M-2.27(Dambara, 1966).Then, the duration period of anomalous crustal movement and the radius of anomalous area seems to be in linear relation, r=3.4km/year·t.This fact can be interpreted as follows. As anomalous crustal movement appears, the dilatancy starts from nucleus points or lines in the area and grows out with the constant velocity of several kilometers per year. The existence of this kind of propagation can be assumed from the equation of diffusion in the theory of porous medium. Finally the dilatancy will fill up some volume, which may correspond to the earthquake volume. The author discussed in other paper the horizontal propagation of precursory movement in case of the Niigata earthquake of 1964, and found that the velocity of expansion is 2-3km/year in its beginning and 10km/year in the last. This observed velocity shows a good coincidence with the derived value mentioned above.

The magnetic properties and structure of alloy YuNDK15 with tin, indium, and gallium

1. Alloying the YuNDK15 alloy with 2% Sn, 1% In, or 0.6% Ga increases the maximum magnetic energy of the alloy by 30–40%. 2. Tin, indium, and gallium increase the resistance of the β2 solid solution to high-temperature decomposition, which makes it possible to reduce the thermomagnetic treatment temperature to 900–950°C. 3. X-ray structural analysis indicates that tin, indium, and gallium enter into the composition of the β and β and β2 phases.

THE CHEMISORPTION OF NITROGEN ON POLYCRYSTALLIN TUNGSTEN WIRES

Desorption spectra have been obtained for successively increasing amounts of nitrogen adsorbed on three polycrystalline tungsten wires at room temperature. Two β phases were desorbed, β1 with first-order kinetics and an activation energy of 73 kcal/mole and β2with second-order kinetics and an activation energy of 75 kcal/mole. Surface impurities such as carbon or thorium reduced the size of the β1 phase. Mass spectrometric evidence showed that the small α phase was adsorbed as molecules, and the β1 and β2 phases were adsorbed as atoms.