Effect of a small addition of Cr on soft magnetic and mechanical properties of Fe–49Co–2V alloy

Fe–49Co–2V–0.5Cr and Fe–49Co–2V alloys were prepared by hot and cold rollings combined with subsequent annealing at temperatures ranging from 550 to 850 °C. The Fe–49Co–2V–0.5Cr alloy annealed under an appropriate condition shows low coercivity of 2.6 Oe as well as an enhanced tensile strength of 912 MPa and elongation of 10.9% as compared to Fe–49Co–2V. The improved mechanical properties are consistent with fracture morphologies which demonstrate a quasi-cleavage feature for the annealed Cr-added alloy, which is revealed to be relevant to a precipitation process that is facilitated by the Cr addition occurring prior along grain boundaries and even in the grain interiors when annealed at higher temperatures. Transmission electron microscopy combined with electron probe micro-analyzer is applied to identify the precipitates and reveals that they are comprised by numerous small-sized particles enriched with V and Cr, which suggests be beneficial for a good combination of magnetic and mechanical properties.

► Annealing dependent strength and elongation is greatly affected by the Cr addition.
► Good mechanical properties are shown along with low coercivity for Fe–49Co–2V–0.5Cr.
► A small addition of Cr facilitates precipitation for the annealed alloy.
► TEM observation reveals that the precipitates are comprised of small-sized particles.