Influence of thermal treatments on the mechanical properties of an FeCoV alloy (remendur)

Effect of heat-treatment on the room temperature ductility of an ordered intermetallic Fe–Co–V alloy

“…3a). This is typical of an alloy undergoing martensitic transformation [2]. The average grain size of the alloy is 35 m. In addition, the mi- crostructure contains precipitates, rich in niobium (Fig.…”

“…Thornburg [19], and Stoloff and Dillamore [20] reported that the room temperature yield strength of a cold worked FeCo alloy, with 1.5-2.0% V, decreases with increasing annealing temperature, while the ductility peaks in the ordered region. On the other hand, the ductility peak was observed in the disordered region when the vanadium content is 3 wt.% [2]. In addition, the higher vanadium alloy also exhibited a peak in yield strength when annealed at 600-625 • C. Factors such as high dislocation density, fine precipitation, and fine grain size increase yield strength, while recrystallization, grain growth, dissolution of precipitates, and change in texture lead to a loss in strength [2].…”

“…Similar microstructure is also observed in samples water quenched after heat-treating at 950 • C for 1 h. Additional ordering treatment at 600 • C did not cause any appreciable change in microstructure when examined by SEM. When the quenched alloy is aged at temperatures below the order-disorder transformation temperature, the disordered ␣ 2 transforms to equilibrium ␣ and precipitates of ␥ 2 phase [2,13]. However, we did not observe any changes in the SEM microstructure of the alloy (heat-treated at 950 • C/1 h/AC) after the ordering treatment at 600 • C. Further TEM examination of the samples may be necessary to reveal the fine (␣ + ␥ 2 ) product formed during the decomposition of metastable ␣ 2 .…”

“…The addition of vanadium enhanced the room temperature ductility. Ternary FeCo-V alloys were found to be cold workable up to 90% in the disordered state [2][3][4]. Cold rolled sheets of commercial FeCo-V alloys are heat-treated between 600 and 900 • C to achieve a balance between the mechanical and magnetic properties.…”

“…Introduction of order in the binary and in the FeCo-V alloys results in ductility loss at room temperature [2,5,6]. However, Kawahara [3,4] has shown that the ductility of the FeCo-V alloys in the ordered condition can be improved by cold rolling the alloys above 70%.…”