Microstructure, mechanical properties and corrosion resistance of low-cost Ti–Al–Cr–Fe alloys processed via powder metallurgy

Abstract

A variety of economical Ti–3Al–6Cr-xFe (x = 0, 1, 2 wt%) alloys were prepared utilizing typical powder metallurgy (cold pressing and sintering) to explore the impact of Fe concentration on the densification behavior, phase evolution, microstructure, mechanical properties and corrosion resistance. The inclusion of Fe increases the compressibility. The high diffusivity of the Fe element contributes to the densification but excessive Fe inclusion causes Kirkendall pores to develop. Therefore, Ti–3Al–6Cr–1Fe has the highest density. Every alloy is made up of intermetallic (TiCr2), α, and β phases. The proportion of the β phase rose with the addition of Fe. The optimal combination of mechanical characteristics was obtained by Ti–3Al–6Cr–1Fe (ultimate tensile strength of 1093 MPa and ductility of 3.1%), which is explained by the interaction of higher density and solid solution strengthening effects. Ti–3Al–6Cr–2Fe has the greatest corrosion resistance due to the relatively high density and maximum β phase proportion.