Open AccessCATASTROPHIC OXIDATION OF AISI M4 ALLOY
Author(s) -
Gabrijela Čevnik,
Jožef Medved,
Aleš Nagode,
Mirko Gojić,
Borut Kosec,
M. Bizjak
Publication year - 2021
Publication title -
materiali in tehnologije
Language(s) - English
Resource type - Journals
eISSN - 1580-3414
pISSN - 1580-2949
DOI - 10.17222/mit.2021.141
Subject(s) - materials science , alloy , oxide , annealing (glass) , electron microprobe , metallurgy , scanning electron microscope , ferrous , vanadium , optical microscope , oxygen , atmospheric temperature range , chemical engineering , composite material , chemistry , engineering , physics , meteorology , organic chemistry
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 during high-temperature annealing in oxygen atmospheres. The rate of oxidation is so great that it is considered a catastrophic oxidation. In this work, the AISI M4 alloy was investigated. The mechanism and model of the oxidation of alloy AISI M4 were developed on the basis of an analysis of the oxidation in a temperature range of 700–1000 °C. The holding time was 6 h. The alloy was analysed with an optical microscope and scanning electron microscopy equipped with EDS, WDS and EPMA detectors. It was found that below 850 °C, molten oxide is formed, which is predominantly of V2O5 composition. Above 850 °C, the oxide layer is multi-layered. The oxide layer consists of complex oxides, which formed with other elements. The X-ray analysis confirmed the presence of the following oxides in the oxide layer: Fe2O3, Cr2O3, FeVO4, V2O3 and Fe2WO6; and the second oxide may additionally be: V2O5, Cr2O5 and FeWO4.