Nanostructured Hypoeutectic Fe-B Alloy Prepared by a Self-propagating High Temperature Synthesis Combining a Rapid Cooling Technique.

We have successfully synthesized bulk nanostructured Fe94.3B5.7 alloy using the one-step approach of a self-propagating high temperature synthesis (SHS) combining a rapid cooling technique. This method is convenient, low in cost, and capable of being scaled up for processing the bulk nanostructured materials. The solidification microstructure is composed of a relatively coarse, uniformly distributed dendriteto a nanostructured eutectic matrix with α-Fe(B) and t-Fe2B phases. The fine eutectic structure is disorganized, and the precipitation Fe2B is found in the α-Fe(B) phase of the eutectic. The dendrite phase has the t-Fe2B structure rather than α-Fe(B) in the Fe94.3B5.7 alloy, because the growth velocity of t-Fe2B is faster than that of the α-Fe with the deeply super-cooling degree. The coercivity (Hc) and saturation magnetization (Ms) values of the Fe94.3B5.7 alloy are 11 A/m and 1.74T, respectively. Moreover, the Fe94.3B5.7 alloy yields at 1430 MPa and fractures at 1710 MPa with a large ductility of 19.8% at compressive test.