The oxidation behaviour of aluminium-rich coatings on the TiAl alloy TNM-B1

A.S. Ulrich, N. Laska, A. Straubel, C. Leyens, R. Braun, M.C. Galetz, M. Schütze

To improve the oxidation resistance of a third generation Ti–Al alloy (TNM-B1) at high temperatures, aluminium rich coatings were deposited using pack cementation and magnetron sputtering. The coatings formed were analysed and compared with respect to phases formed and the containing elements. Oxidation tests were carried out on the additionally fluorine treated and preoxidised samples at 900 C in air. Compared to uncoated samples the beneficial effect of coating deposition was confirmed. Additionally, the concentration of incorporated oxygen in the subsurface zone and its influence on the mechanical properties were investigated using EPMA and microhardness measurements. Oxygen concentrations were determined for the three phases of the substrate material -TiAl, -TiAl, and -Ti(Al), and depended on the previous coating layer deposition.

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