Limitations on the use of ion implantation for the study of the reactive element effect in [beta]-NiAl

• Published in: Journal of the Electrochemical Society 1994-09, Vol.141:9
• Main Authors: Pint, B.A., Hobbs, L.W.
• Format: Article
• Language: English
• Subjects: 360105 > Metals & Alloys-- Corrosion & Erosion; ALLOYS; ALUMINIUM ALLOYS; ALUMINIUM COMPOUNDS; ALUMINIUM OXIDES; CERIUM; CHALCOGENIDES; COATINGS; DATA; ELEMENTS; EXPERIMENTAL DATA; INFORMATION; INTERMETALLIC COMPOUNDS; ION IMPLANTATION; MATERIALS SCIENCE; METALS; NICKEL ALLOYS; NUMERICAL DATA; OXIDES; OXYGEN COMPOUNDS; PASSIVATION; PROTECTIVE COATINGS; RARE EARTHS; STABILITY; TRANSITION ELEMENTS 360106 > Metals & Alloys-- Radiation Effects; YTTRIUM
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.2055140

Numerous investigations have used the ion implantation of reactive elements (RE) such as Y or Ce, to study their effect on the growth of external oxide scales on alloys. Ion implantation has, nevertheless, some specific limitations, especially in Al[sub 2]O[sub 3]-forming alloys. The most notable limitation occurs at temperatures > 1,000 C where, owing to the shallowness of implantation, any effects of the ion-implanted RE are short-lived and differ significantly from those observed for an RE alloy addition or an RE oxide dispersion. Additionally, in alumina-forming alloy systems, particularly [beta]-NiAl, implanted Y stabilizes the first-forming, metastable [theta]-Al[sub 2]O[sub 3]. The retention of the [theta]-Al[sub 2]O[sub 3] scale on Y-implanted substrates is a chemical effect of the high concentration of Y near the substrate surface and is not a result of the implantation process itself. The loss of the RE effect at high temperatures and long times for implanted alloys is related to the outward diffusion of the RE and the information of RE-rich oxides near the gas interface of the scale.