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M: Metallphysik

M 41: Postersitzung

M 41.7: Poster

Donnerstag, 27. März 2003, 14:30–16:30, HSZ

Extraction of boron from Fe₈₀B₂₀ ribbons by annealing under hydrogen flow — •Gabriela Saage, Stefan Roth, Jürgen Eckert, and Ludwig Schultz — IFW Dresden, Institute of Metallic Materials, POB 27 01 16, D-01171 Dresden

Extraction of boron from amorphous melt-spun ribbons is investigated as a method of preparing ribbons of alloys with brittle behavior. The possibility to prepare such alloys as ribbons by melt spinning is relieved by adding to the initial composition a certain amount of glass formers (in our case 2-4 wt. bend ductility. Further, after the preparation of the ribbons in the wanted form, the glass former will be extracted by annealing the ribbons in a reactive atmosphere. In the present study the gas-solid reactions are investigated from a more fundamental point of view. Ribbons Fe₈₀B₂₀ 10 µmm wide and 20-25 µm thick were prepared by melt-spinning. Simultaneous thermogravimetrical and single diffe-rential thermal analysis (sDTA) were performed in a STA 429 Netzsch analyzer The mass loss was measured with heating rates of 2.5, 5 and 10 K/min from room temperature up to 1150 ^∘C. The analysis of these data was performed with the NETSCH Thermokinetics program.After crystallization the extraction is governed by three independent reactions. The first one is the hydrogen absorbtion, which is diffusion controlled and has the lowest activation energy. The second is boron desorption from the borides into the matrix (boride decomposition) and the third reaction is the boron extraction from the α-Fe matrix of the ribbon into the atmosphere.