Hydrogenation of Amorphous and Crystalline RE-Ni Alloys

Amorphous alloys with the combination of a rare earth metal(RE=Y, La, Ce, Pr and Sm) and nickel were prepared around the composition at an eutectic point by the melt-quenching technique. Amorphous Y-Ni and Sm-Ni alloys absorbed a large amount of hydrogen even in the amorphous state, while the the other alloys in La-Ni, Ce-Ni and Pr-Ni systems were decomposed to a mixture of crystalline phase and hydride during hydrogenation at 323 K. An amorphous SmNi_2 phase was also synthesized by reaction of hydrogen gas with the crystalline SmNi_2 compound below about 500 K. The hydrogen absorption capacity of the melt-quenched amorphous Sm-Ni alloys was smaller than those of both the corresponding crystalline alloys and the amorphous SmNi_2 alloy obtained by reaction of hydrogen

The Magnetic and Electric Properties of (Co_<1-x> Mn_x)_2B Crystalline compounds and Amorphous Alloys

The manganese concentration x dependence of the average magnetic moment μo, the Curie temperature Tc, the pressure effect on Tc and the electric resistance for the ferromagnetic amorphous alloys (Co_ Mn_x)B were investigated. The Curie temperature decreases linearly with increasing x and μo had a maximum around x=0.15. The magnetic susceptibility vs. temperature curves for all the prepared amorphous alloys obey the Curie-Weiss law above Tc. The pressure effect on Tc is that Tc has a value of 1.06 K/kbar at x=0 and is decreasing with increasing x and becomes zero at x=0.4. These results are analyzed on the basis of the pair interaction model and the local enviroment effect. There arise two kinds of minimum in the resistance vs. temperature curves. That the resistance minimum at high temperature has a strong correlation with Tc is assured by measuring the transverse effect of the resistance with amorphous alloys x=0.4. The resistance minimum for the amorphous alloys and crystalline compounds are found at low temperature under ferromagnetic state

Crystallization and Electrical Properties of Amorphous Cu-Ag-P Alloys

Amorphous Cu-Ag-P alloys (Cu : 79～86, Ag : 6～14, P : 11～14 wt%) were prepared by melt-quenching technique. The crystallization process of these amorphous alloys was examined by electrical resistivity, X-ray diffraction and differential thermal analysis techniques. The T-T-T diagram of the amorphous Cu-Ag-P alloys could be divided into five distinct regions and the electrical resistivity of these alloys decreased in the order of amorphous → metastable-I → supersaturated metastable → metastable-II → stable state. Compared with traditional strain gauge materials, the present amorphous alloys exhibited a higher gauge factor (1.8～3.1), lower thermal electromotive force relative to copper (1.07μv/℃), comparable specific resistivity at room temperature (80μΩ・cm) and higher negative temperature coefficient of specific resistivity (-0.7～-1.2x10^/℃). These values showed to be useful as guage materials below the crystallization temperature

Densities of Metal-Metalloid Amorphous Alloys

Binary, ternary and quaternary Fe-, Co- and Ni-base amorphous alloys containing metalloid elements of B, Si or P were produced by a melt quenching technique. Densities of these amorphous alloys were measured by the liquid displacement method using tetrabromoethane (Br_2CHCHBr_2). The concentration dependence of the densities, in particular the metalloid concentration effect, indicates that the structural features of amorphous alloys with lower metalloid concentration differ slightly from those of higher metalloid concentration alloys. This is consistent with the concept of two amorphous structure recently suggested as a novel picture for the structure of amorphous alloys. The effect of replacing metallic elements on the structural features is less sensitive than the changes as a function of metalloid concentration

Magnetic Properties of Amorphous Fe-Zr-B Alloys

The formation range, magnetic properties and thermal stability for Fe-Zr-B amorphous alloys have been examined. The combination of zirconium and boron as glass formation elements is extremely effective both in expanding the formation range and increasing stability against crystallization for Fe-based amorphous alloys. Both the Curie temperature and saturation magnetization at room temperature decrease with increasing Zr content. Magnetostriction for the present alloys is smaller than that of metal-metalloid alloys possessing the same magnitude of saturation magnetization. There is no variation in coersive force on isothermal aging at 150℃ for time up to 10^4 minutes