Effect of Ti addition on the mechanical properties and microstructure of novel Al-rich low-density multi-principal-element alloys

Abstract

In this work, the effect of Ti content on the microstructure and mechanical properties of low-density Fe-30Mn-10Al-1.57C-2.3Cr-0.3Si-χTi (χ = 0, 0.3, 0.6, and 0.9 wt%) alloys was systematically investigated. The results reveal that hot deformation, followed by solid-solution treatment at 1050 °C (3 h) and thermal aging at 350 °C (6 h), ensures outstanding mechanical properties. The low-density alloys exhibit completely austenite microstructures with carbides. The original carbide phase, the so-called κ-carbide, is observed in the low-density Ti-free specimen. However, increase in the Ti content leads to the reduction of this phase and the emergence of a new type of carbide, i.e., TiC. Moreover, the grain size of austenite phase is refined with Ti addition, resulting in a superior yield strength. In addition, the low-density alloy with a Ti concentration of 0.6 wt% demonstrates optimal mechanical properties with the yield strength of 1031.75 MPa, the ultimate tensile strength of 1158.55 MPa, and the total elongation of 23.96%. It is worth noting that the novel low-density alloy exhibits a density of 6.65 g/cm3, which is ~14.74% lower than that of traditional steel (7.8 g/cm3) and can be ascribed to the incorporation of lightweight Al element.