Effect of Sn on microstructure and mechanical properties of Ti-Fe-(Sn) ultrafine eutectic composites

Abstract

High strength (Ti0.705Fe0.295)100-xSnx (0 ≤ x ≤ 6) composites have been prepared through arc melting and cold crucible casting. The microstructure consists of two phase ultrafine eutectic comprised of FeTi and β-Ti phases. The effect of Sn addition to the Ti70.5Fe29.5 eutectic is assessed in terms of microstructure variations such as eutectic spacing, morphology, cell size, lattice parameter of the phases, and the resulting mechanical properties in terms of strength and plasticity under compression. The mechanical properties (maximum strength 1939 MPa, fracture strain 13.5%) of the ternary Ti-Fe-Sn (2 ≤ x ≤ 6) are considerably improved compared to the Ti70.5Fe29.5 binary alloy (1733 MPa, 3.4%). The change in the morphology of the eutectic, the microstructure refinement, structural fluctuations, and supersaturation in the β-Ti phase, and the elastic properties of nanophases are crucial factors for improving the plastic deformability of the ultrafine eutectic alloys without presence of any additional micrometer-size toughening phase.