Naslov
Catastrophic oxidation of AISI M4 alloy

Autori
Čevnik, Gabrijela ; Medved, Jožef, Nagode, Aleš ; Gojić, Mirko ; Kosec, Borut ; Bizjak, Milan

Izvornik
Materiali in tehnologije (1580-2949) 55 (2021), 4; 585-590

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
catastrophic oxidation, internal oxidation, vanadium, iron alloys, diffusion, kinetics

Sažetak
In the annealing of some pure metals and various alloys, the phenomenon of accelerated oxidation is known, which is due to the fact that the resulting surface oxides fail to inhibit or completely stop the oxidation process. Vanadium ferrous alloys are rapidly oxidized under high temperature annealing in oxygen atmospheres. The rate of oxidation is so great that it is considered a catastrophic oxidation group. In this work the AISI M4 alloy was investigated. The mechanism and model of oxidation of alloy AISI M4 were developed on the basis of the analysis of oxidation in the temperature range from 700oC to 1000oC. The holding times was 6 hours. The alloy analysed with an optical microscope and scanning electron microscopy equipped with EDS, WDS and EPMA detectors. It was found that below 850oC, molten oxide is formed, which is predominantly of V2O5 composition. Above 850oC, the oxide layer is multi-layered. The oxide layer is consisted from complex oxides which are formed with other elements. X-ray analysis confirmed the presence of the following oxides in the oxide layer: Fe2O3, Cr2O3, FeVO4, V2O3 and Fe2WO6, and in the second oxide additionally: V2O5, Cr2O5 and FeWO4.

Izvorni jezik
Engleski

Znanstvena područja
Metalurgija

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