Effects of Fe-6.5wt.%Si alloys prepared by different cooling methods on ordered structure and mechanical properties

The non-oriented Fe-6.5wt.%Si alloy cast strip with a width of 100 mm and a thickness of 1.7 mm was prepared by the top side-pouring twin-roll-casting (TSTRC) process. The surface quality of the air-cooled and water-cooled cast strip was good. Compared with the Fe-6.5wt.%Si alloy ingot, the Fe-6.5wt.%Si alloy cast strip has a fine solidification structure and exhibits certain plasticity at room temperature. Microhardness, XRD, and TEM investigated the ordered structure and degree of Fe-6.5wt.%Si alloys prepared by three different cooling methods. The results show that the Fe-6.5wt.%Si alloy ingot prepared by the standard method has many B2-ordered phases and D03-ordered phases, and the order degree is high. The Fe-6.5wt.%Si alloy cast strip prepared by the TSTRC process has a low degree of order and only contains a small B2-ordered phase. The faster cooling rate effectively inhibits the formation of the D03-ordered phase and B2-ordered phase. The growth of the ordered phase also reduces the reverse domain boundary energy, reduces the motion resistance of superdislocations, and increases its mobility, thereby improving the room temperature plasticity of Fe-6.5wt.%Si alloy cast strips.