The mechanical and electrical properties of 6.5 wt.%Si steel for advanced electric components

Fracture behavior and electrical resistance of poly crystals and single crystals of Fe-6.5wt%Si alloy were studied. Electrical resistivities were measured versus temperatures from room temperature to 1000°C. Single crystals were prepared using the floating zone (FZ) method, which melts the alloy using a high temperature electron beam in pure argon gas. The single crystals were annealed at 500°C and 700°C respectively and tensile tests and high-strain-rate deformation tests were performed at room temperature. Disordered body-centered cubic α-iron (A2), ordered bcc α₂-iron (B2), and ordered hexagonal close-packed α₁-iron (DO₃) phases were formed in samples annealed at 1000°C/1 h, 700°C/1 h, and 500°C/1 h, respectively. The main results are as follows: (1) B2 and A2 phase have elongations of 0.58% and 0.57%, respectively. The DO₃ phase has a lower elongation of 0.49%. It is shown that B2 and A2 phase have better elongations. (2) The electrical resistance of the single crystal is better than that of the polycrystal. (3) Fe-6.5wt.%Si alloy has higher strength at high-strain-rate tensile. SHPB results of polycrystal are twice as high as the static results. (4) From the fractography, the cleavage steps are remarkably reduced in the SHPB (split Hopkinson pressure bar) test compared with the static test. (5) The resistivity of the alloy is highest at the B2 phase single crystal