Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Titanium alloys cannot be used at elevated temperatures above approximately 500°C because of their limited environmental stability. Several ways have been investigated so far to improve the environmental stability of Ti-alloys e.g. coatings but these attempts in a majority of cases have not been really successful. A new way to improve the performance of these alloys is the combination of Al-enrichment in the surface zone plus additional fluorine treatment. The Al-enrichment leads to the formation of intermetallic phases. These phases improve the oxidation resistance of Ti-alloys but not to a sufficient extent. An additional fluorine treatment on top of the Al-enriched surface leads to the formation of a stable alumina scale due to the fluorine effect. In this paper results from oxidation and other tests performed on Ti-samples without any treatment, with single Al- or F-treatment and with a combination of both are presented and the results are discussed.