Mössbauer spectroscopy and X-ray diffraction studies of ball-milling-induced transformations of a near-equiatomic FeV sigma phase: Influence of oxygen

Abstract

Abstract57 Fe Mo¨ssbauer spectroscopy and X-ray diffraction were used to study the structural changes induced by ball milling a coarse-grained Fe 48.1 V 51.9 at% sigma phase in a vibratory mill in argon with a frequent gas renewal. The sigma phase transforms into a bcc alpha phase till 140 h of milling. Mo¨ssbauer spectroscopy also shows the presence of an amorphous phase. Further, X-ray diffraction and Mo¨ssbauer spectroscopy reveals the presence of a corundum type oxide (V 1-x Fe x ) 2 O 3 and of a spinel FeV 2 O 4 in samples milled for 140 h and longer. Mo¨ssbauer spectroscopy clearly shows that the spinel phase starts to form after 140 h of milling. Oxidation is progressive and occurs first via an unmixing process which deprives the Fe-V bcc matrix of vanadium atoms. r

Suppression of σ-phase in nanocrystalline CoCrFeMnNiV high entropy alloy by unsolicited contamination during mechanical alloying and spark plasma sintering

“…Since, more V gets into this oxide, the experimentally observed carbide phase is not dominated V, but the next strong carbide former namely, Cr. The preferential oxidation of V during MA and its adverse effect on σ-phase stability has also been exemplified for binary alloys such as Fe 48.1 V 51.9 [24][25][26].…”