ISSN:
1573-4889
Keywords:
Ni–8Cr–3.5Al
;
nanocrystallization
;
oxidation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Magnetron-sputter deposition was used to produce a Ni–8Cr–3.5Al(wt.%) nanocrystalline coating on substrates of the same alloy. Theoxidation behavior of the cast Ni–8Cr–3.5Al alloy and itssputtered coating were investigated at 1000°C in air. Complex,layered-oxide scales composed of Cr2O3 outer layer,mixed spinel NiAl2O4 and NiCr2O4middle layer, and α-Al2O3 inner layer were formedon the Ni–8Cr–3.5Al nanocrystalline coating during 200-hroxidation, whereas Cr2O3, with some NiCr2O4external layer with internal Al2O3, formed on the castalloy. Because of the formation of this α-Al2O3inner layer on the coating, the sputtered Ni–8Cr–3.5Al coatingshowed better oxidation resistance than the cast alloy. The effect ofnanocrystallization on oxide formation is discussed. It was indicated thatthe formation of this α-Al2O3 inner layer was closely related to therapid diffusion of Al through grain boundaries in the nanocrystallinecoating and the relatively high Cr content in Ni–8Cr–3.5Al.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1004610931447
