Aspects of phase equilibria in Fe/Co/2.5 to 3.0% V alloys

Near equiatomic FeCo alloys: Constitution, mechanical and magnetic properties

“…They also estimated the composition of the precipitate phase to 22V-65Co-15Fe (wt%). Bennett and Pinnel [7] noted the inconsistency between the composition proposed in [25] and the isotherm section of Fe-Co-V proposed by Koster and Schmidt [21], which places the c formed at low temperature in the a + c + c 2 field. However, the problem remained discussed in terms of a + c equilibrium (for example [8,26] of Ashby et al [10], who proposed that the phase precipitating at low temperature is not c but a Fe-substituted variant of the Co 3 V compound, (Fe,Co) 3 V, with LI 2 structure (ordered f.c.c.…”

“…However, it appears that the exact stoichiometry has sometimes been neglected in comparisons. For example, while some of the values obtained by Martin and Geisler [16], or Ashby et al [10] are for equiatomic content in Fe and Co, other values are for alloys with identical wt% of Fe and Co, which corresponds to an excess of Fe in at% (for example, [7]. [21,22]; s are points identified as single-phased regions and d as two-phases regions.…”

“…phase has been referred to as c, the disordered b.c.c. phase as a 1 , and its ordered state as a 0 1 (for example [7]). …”

“…A number of studies have focused on the determination of the a/a + c and a + c/c boundary [7][8][9][10][16][17][18]. It is undisputed that vanadium additions reduce both the a/ a + c and a + c/c transition temperatures (further denoted T a/a+c and T a+c/c ).…”

“…4. The a/a + c and a + c/c boundaries as a function of vanadium content in an equiatomic FeCo alloy, as measured by Martin and Geisler[16] by thermal analysis (lines, dotted lines are average of values measured during cooling and heating), and comparison with other published data[7,10,16]. Filled points represent values for equiatomic compositions, empty points indicate alloys with excess Fe (addition of V at the expense of Co) and crossed points indicate alloys with excess Co (addition of V at the expense of Fe).…”