Inflammability of Melt-Spun Zr-Based Metallic Glasses

摘要

Zr-based metallic glasses can be produced by melt-spinning as thin ribbons, in a number of cases also by more conventional casting methods as bulk material. For any application, as a structural material, a material for hydrogen or deuterium storage as well as for heterogeneous catalysis, adequate oxidation and corrosion resistance have to be ensured. Some Zr-based metallic glasses, however, are known to oxidize even at very low temperatures. Therefore, it is urgent to verify whether these materials are combustible or even exhibits spontaneous ignition. The inflammability of several melt-spun ribbons, in particular Zr_(67)Fe_(33) was studied by heating with an increasing electrical current or by insertion into a flame. The microstructures produced during the burning was analyzed by optical as well as electron microscopy and X-ray diffraction. These results allow conclusions on the proceeding oxidation processes which will be compared to those during controlled isothermal oxidation at lower temperatures. Oxidation resistance near T_g and ignition resistance was observed to increase in the sequence of the late transition metals: Fe→Ni→Cu. Glowing or ignition of the ribbons is correlated with their melting as confirmed by microstructural analysis. The scale consists of broad monoclinic ZrO_2 columns on top of a very thick (molten) matrix enriched with the late transition metal.