Influence of alloy additions on oxidation

Abstract

Some of the i~portant principles of alloy oxidation are discussed, with emphasis on the formatIOn of protective Cr 2 0 J , AI 2 0 J , and Si0 2 scales on iron and nickel base alloys. The competition between internal and external oxidation is consid~red and it is sho~n how establishment of the protective layer is influenced by va~lOus. p'ar~meters, Including alloy interdiffusion coefficient, oxygen solubility and~iffUSlVltym the alloy, and the relative growth rates of the various oxides. The lmportance of the t~ansient stage of oxidation is emphasised, with particular reference to the populatwn densities of the initial nuclei of the protective oxide and~herates of gr~wth~nd c:oa~escence of these particles to develop the healing barr~erlay'er. ConslderatlOn lS glven to the effectiveness of the protective scales iñ ervlce, wah respect to transport processes and mechanical integrity. The mfluence of the minor alloying elements, manganese, titanium, aluminium, silicon molybdenum, and niobium, on oxidation of Cr 2 0 J forming alloys is discussed. ' MST/1017

Oxidation of Al-Co Alloys at High Temperatures

“…Irving et al found that a protective alumina scale can be formed when Al concentration 24 at.% at 1173 K is reached. Comparable minimum Al concentrations required to form the external alumina scale were also found for the Ni-Al and Fe-Al alloys [89].…”

“…13, x FOR PEER REVIEW 12 of 18minimum Al concentrations required to form the external alumina scale were also found for the Ni-Al and Fe-Al alloys[89].…”

High Temperature Corrosion of Cast Alloys in Exhaust Environments. II—Cast Stainless Steels

“…Silica acts here as a diffusion barrier and reduces therefore the cation diffusion rate through the oxide [12,33,[35][36][37]. Since silica forms fairly slowly [38,39], the establishment of a continuous layer is a lot more difficult under the fast growing pits than elsewhere. Actually, even after 200 h, a continuous healing layer was still not fully established in Diesel at 850°C.…”

Materials Selection for the Lead-Bismuth Corrosion and Erosion Tests in DELTA Loop

“…The presence of Cr, Si, as well as Al, is known to improve steels corrosion resistance. Al as minor alloying element in steels have been shown to enhance corrosion resistance [11,12] The following sections discuss the materials selection for the DELTA loop test matrix, as well as corrosion specimen loading in a redesigned holder that allows high LBE velocity and more specimens simultaneous testing. As mentioned previously, Section 3 will describe corrosion specimen preparation and loading.…”