Mechanical Properties of Melt-Spun Amorphous Ni-Nb-Zr Alloys after Hydrogen Charging

The effect of pre-charged hydrogen on the mechanical behavior of melt-spun amorphous Ni-Nb-Zr alloys was investigated. A substantial increase in the tensile fracture strength is observed even in hydrogen content up to about 46 at%. The Vickers hardness gradually increases with an increase in hydrogen content up to about 27 at%, and keeps almost the same value in the higher content more than 46 at%. It might be said that the amorphous (Ni0.6Nb0.4)70Zr30 alloy is not embrittled distinctly even in the high hydrogen content at room temperature. The amorphous alloy ribbons always curled during hydrogenation and the outer side of the curled ribbon corresponds to the roll side due to preferential absorption of hydrogen. XPS study revealed that the zirconium content in the surface film of the roll side surface is lower than that of the top side surface. The difference in surface composition as well as higher surface roughness of the roll side surface seems responsible for the preferential hydrogen absorption.