Development of ultrafine eutectic in Ti-Fe-Bi alloys during solidification in a massive stepped Cu-mold

Abstract

The Ti-based alloys are important alternatives to replace Fe and Zr alloys due to the lower density values. As a consequence, such alloys may be potentially used in automotive and aerospace applications. Although Ti-Fe alloys are able to depict high strength values (1500-2000MPa), ductility is quite low, which can difficult their usage. Several rapid solidification systems have been used in order to produce Ti-Fe structures which can permit higher mechanical strength associated with ductility and appreciable thickness. Both eutectic size and morphology are controlled by cooling rate and such features can be decisive on the final properties. The literature is scarce on researches concerning not only correlations among cooling rates and microstructures but also relations like microstructure-mechanical behavior. The stepped Cu-mold may allow a large experimental structure spectrum to be obtained. The measured dendritic and/or interphase spacing may be correlated with the structure development within the mold. The aim of this research is to perform rapid solidification experiments with Ti-Fe alloys modified by small additions of Bi. The final results include: ultimate tensile strength, yield tensile strength and total elongation. Furthermore, special attention will be given for nature, size and morphology of intermetallics on the eutectic regions.