Untersuchung über Zustandsänderungen von Eisen‐Vanadin‐Legierungen

Abstract

Untersuchungen über die Temperaturabhängigkeit des Elastizitätsmoduls, der Magnetisierung, des elektrischen Widerstandes und der Wärmeausdehnung von Eisen‐Vanadin‐Legierungen mit 14, 27 und 45% V zwischen 350 und 1100°. Bildungsdauer von Keimen der Sigmaphase unterhalb 700° bei den Legierungen mit 27 und 45% V. Entstehung metastabiler Ordnungsvorgänge auf Grund der Instabilität des Mischkristalles. Fernordnung bei der Legierung mit 45% V, Nahordnung bei der Legierung mit 27% V. Nach längerer Glühdauer bei höheren Temperaturen Übergang in Sigmaphase.

Phase transformations in alloys of the Fe–V system

“…As mentioned above, it is agreed that the existence region of the -phase in the Fe-V system does not close at low temperatures [1,2]. At the same time, some other authors [4,5] believe that at 650 • C and below the ordered B2-phase is formed but not the -phase.…”

“…However, there is no agreement among the authors regarding the mechanism and temperature of the -phase formation. For example, it is believed [2,3] that prior to the formation of the stablephase, the equiatomic bcc Fe(V) solid solution transforms to a metastable ordered phase having a B2 type structure and thereafter the B2 → -phase transition takes place in the alloy. Seki et al [4] have estimated the metastable CsCl-type order-disorder transition temperature as equal to 850-880 • C for the equiatomic composition.…”

“…At present there is no report which has dealt in particular with the mechanism of the -phase formation. To this, we can add one more conflicting conclusion: it turns out that a solid solution, which can be retained by rapid cooling from the homogeneity range, transforms to the CsCl-type ordered phase (B2) on staying at temperatures below 650 • C [2,3]. The "650 • C anomaly", which corresponds to the 550 • C anomaly in Fe-Co alloys and the 730 • C anomaly in V-Mn alloys, is observed in the ordered Fe-V alloys after prolonged heating [4,5].…”

Sigma-Phase in Fe-Cr and Fe-V Alloy Systems and its Physical Properties

“…The reason for such behaviour is not clear but it may reflect the effect of size of grains of σ or some re-arrangement of atoms within the new crystallographic structure in the course of its growth. The occurrence of the ordered superstructure (B2) is also possible, as it is known to happen in the Fe-V system [46].…”