Chemical heterogeneity-induced plasticity in Ti–Fe–Bi ultrafine eutectic alloys

Microstructure development and mechanical properties of rapidly solidified Ti–Fe and Ti–Fe–Bi alloys

“…7. This minor presence of Bi within the intermetallic is due to small alloy Bi content and further low solubility of Bi in the binary FeTi compound, in agreement with the EDS results showed by Lee et al [9] for (Ti 70.5 Fe 29.5 ) 99 Bi 1 (at.%) alloy.…”

“…This dissolution of Bi in both phases as cited has also been observed by Lee et al during solidification of the Ti-Fe-(0.3-1.0 at.%Bi) alloys [9]. It is believed that Bi is rejected during solidification leading to the formation of the supersaturated Bi in the TiFe intermetallic particle.…”

“…There is no evident peak shift for the TiFe intermetallic compound. According to Lee et al [9], this could imply that Bi is mostly dissolved into the β-Ti phase rather than in the TiFe intermetallic as an evidence of asymmetrical solubility of Bi in the β-Ti and TiFe compound. However, considering the present experimental configuration such shift may be due to not only minor Bi presence but also due to the rather severe iron (Fe) segregation along the longitudinal axis of the centrifugally solidified casting, i.e., 18.4 wt.%Fe associated with the rod diameter of 2 mm and 20.5 wt.%Fe for the rod of 17 mm.…”

“…This is due to the fact that Bi is considered as one of the few elements able to introduce chemical heterogeneity in the TiFe ultrafine eutectic structure without interferes on the regularity of the structure [9]. Such regularity is frequently associated with the length-scale, volume fraction and morphology of the lamellar structure for Ti-Fe alloys.…”

Enhancement of mechanical properties in a Fe81Nb9B10 ultrafine-eutectic composite with in-situ polygonal pro-eutectic and encapsulating eutectic structure

“…Recently, Park et al suggested that the minor addition of immiscible element is effective to design of high strength and ductile hybrid composites via the formation of multi-modal structure distribution [20] or chemical heterogeneity [21]. More recently, Kim et al reported that the micro-alloying of carbon in the Fe-Zr-Nb ultrafine eutectic dendrite composites can modulate microstructural characteristics through the preferential nucleation of carbide precipitate, resulting in the enhanced plasticity without sacrificing of strength value [22].…”