HYDROGEN SORPTION BY SOME EARLY-LATE TRANSITION METAL GLASSES

Abstract
The hydrogen sorption behaviour of amorphous Cu₅₀Zr₅₀, Ni₅₀ Ti₅₀, Ni₆₁Ti₃₉, Ni₆₂Ti₂₉Zr₉, Ni₆₄Zr₃₆, Ni₆₀Nb₄₀ and Ni₅₀Nb₅₀ obtained by melt spinning is described. The first three alloys have a relatively low crystallization temperature and these alloys either could not be made completely amorphous or crystallized during hydrogen sorption. The highest absorption occurs in Ni₆₄Zr₃₆ : about 0.6 hydrogen atom per metal atom at a temperature of 333 K and a hydrogen pressure of 30 bar. Pressure-composition isotherms of Ni₆₄Zr₃₆ show no pressure plateau in the range of temperatures and pressures investigated. The isotherms of crystalline Ni₆₄Zr₃₆ and the intermetallic compound Ni₁₀Zr₇ do show such a plateau. During 100 cycles of hydration and dehydration of amorphous Ni₆₄Zr₃₆ splinters, of 0.1 mm spalled off from the pieces of ribbon, but disintegration into still smaller particles was not observed. The X-ray diffraction and DSC-scan after 100 cycles are similar to those of as-quenched material. Magnetization and Rutherford-back-scattering results indicate surface segregation of Ni in a 100 times cycled sample.