High temperature aging behavior of high strength 49%Co-1.9%V-0.3%Nb-Fe soft magnetic alloy

Abstract

The magnetic and mechanical properties of 49%Co-l.9%V-0.3%Nb-Fe high strength (0,=90 ksi) soft magnetic alloy were studied after aging at 450'C for up to 8 0 0 h . The magnetic induction B (H. = 10 and 2 5 Oe respectively) decreases rapidly in the first 100 h and approaches a lower limit at about 3 0 0 h. The coercive field remains constant during aging. Tensile specimens aged for 2 0 0 h a t 4 5 0 ' C did not show any changes in the room temperature yield stress and elongation. Transmission electron microscopy identified two precipitate phases: NbC and a Laves phase (hcp. a=4.7A, c=7.72A) . The Laves phase appears in grain boundaries and triple-points and inhibits the grain growth therefore enhancing the mechanical properties.