Thermodynamic Assessment of V-Rare Earth Systems

Abstract

Vanadium is a refractory metal with high melting point (1910°C) that has good structural strength, good room-temperature corrosion resistance, and low thermal neutron-absorption cross section. Vanadium is primarily used as a steel additive to improve the strength of steels by forming stable nitrides and carbides. Addition of yttrium to vanadium alloys can improve the oxidation resistance and mechanical properties. In this work, three binary systems, V-Ce, V-La, and V-Y, were thermodynamically assessed based on the ASM Binary Alloy Phase Diagrams using CALPHAD approach. Self-consistent thermodynamic descriptions for all three systems were obtained.

Coexisting superconductivity and ferromagnetism in the (V0.60Ti0.40)-Gd alloys

“…However, there is a solubility of rare earths in the liquid vanadium when the solute concentration is low [6,7,24,26]. The range over which a homogeneous liquid forms increases with increasing temperature [7,23,6]. Similar behaviour is also observed in Ti-rare earth alloys [7].…”

“…The rare earth elements are immiscible in solid vanadium [6,7,22,23,24,25,26,27]. It was predicted theoretically that no binary Ti-rare earth and V-rare earth compounds will form [27].…”

“…It was predicted theoretically that no binary Ti-rare earth and V-rare earth compounds will form [27]. However, there is a solubility of rare earths in the liquid vanadium when the solute concentration is low [6,7,24,26]. The range over which a homogeneous liquid forms increases with increasing temperature [7,23,6].…”

“…The phase diagram of the (V 0.60 Ti 0.40 )-Gd alloys up to 2 at.% Gd shown in Fig. 2 is constructed by comparing the phase diagrams of V-Gd [6,7] and Ti-rare earth [7] with the metallography images of the present alloys. The V 0.60 Ti 0.40 alloy melts at about 1940 K above which the (V 0.60 Ti 0.40 )-Gd alloys up to 2 at.% of Gd form homogeneous liquid phase.…”

“…Earlier, we have shown that the low of the V 1− Ti alloys is due to the low grain boundary (GB) density [2,4]. Rare earth elements are immiscible in the transition metal elements such as titanium and vanadium [6,7]. Recently, we have shown that the addition of Gd to the V 0.60 Ti 0.40 alloy increases the GB density [8].…”