International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators

4-8 May 2009, Vienna

Application of Accelerators in High Temperature Materials Research

H.E. Zschau and M. Schütze

DECHEMA e. V., Karl-Winnacker-Institut, Frankfurt am Main, Germany

Corresponding Author: zschau@dechema.de

The paper focuses on the application of ion beams in the field of oxidation protection of materials developed for high temperature environments. Turbine blades in aircraft engines and gas-fired power generation turbines are often manufactured of Ni-base superalloys because of their good mechanical properties. In contrast to this their oxidation resistance may be insufficient particularly at temperatures above 1000°C. Oxidation of these Ni-base alloys does not form a pure continuous protective alumina scale on the surface, but rather a complex layered structure. This structure is characterized by a non-continuous alumina scale. However the formation of a dense continuous alumina scale without significant internal oxidation would theoretically be possible, if a “critical” Al-concentration is realized by a surface modification by using the halogen effect. After fluorine ion implantation of specimens of the alloy IN 939 with fluences between 1 x 10¹⁶ Fcm^-2 and 4 x 10¹⁷ Fcm^-2 the fluorine depth profiles were measured with PIGE by using nuclear reactions of protons with the F-nucleus. The fluorine implantation profiles were in good agreement with the calculated profiles by using the Monte Carlo software T-DYN. After the subsequent oxidation (60 h/1050°C/air) metallographic cross-sections were prepared. A distinct dense and protective alumina scale was formed on the surface indicating that a change of the oxidation mechanism was achieved. The best results were found for fluences between 5 x 10¹⁶ and 1 x 10¹⁷F cm^-2. The time behaviour of the implanted fluorine during heating and the early stages of oxidation was studied by using PIGE. The results show the technical potential of the fluorine effect in high temperature applications.

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