The A1 to L1 transformation in FePt films with ternary alloying additions of Mg, V, Mn, and B

Abstract

The impact of ternary additions of Mg, V, Mn, and B on the A1 [face centered cubic (fcc)] to L10 phase transformation has been studied. The films were cosputter deposited from elemental targets at room temperature and annealed after deposition. The films had Mg additions in the range ∼0–2.6 at.%, V additions in the range 0.7–12.2 at.%, Mn additions in the range 2.2–16.3 at.%, and B additions in the range 1.2–12.9 at.%. For all four ternary alloy systems, annealing resulted in the formation of no other phases than the L10 phase. Ternary additions of <1.8 at.% Mg, <5.8 at.% V, <6.0 at.% Mn, and <4.8 at.% B had little or no impact on the kinetic ordering temperature (KOT). The behavior of the activation energy for the transformation mirrored that for the KOT, except for Mg additions, which showed no measurable impact for the compositions studied. The transformation enthalpies for the ternary alloys were similar to those for binary FePt films. Only four of the films (with additions of 2.6 at.% Mg, 2.2 at.% and 6.0 at.% Mn, and 4.8 at.% B) for which the Curie transition was observed had lower TC than the binary FePt films with the same Pt content.