Influence of Ti Addition on Microstructural Evolution, Mechanical Properties, and Corrosion Resistance in Al0.6CrFeNi2.4 Multi-principal Element Alloys

Given the well-established role of Ti as both a reinforcing and passivating element, we designed a series of multi-principal element alloys (MPEAs) based on the ductile and corrosion-resistant Al0.6CrFeNi2.4 alloy. These alloys, denoted as Al0.6CrFeNi2.4Tix (x = 0, 0.2, 0.4, 0.5, and 0.6), aimed at achieving optimal synergy in mechanical properties and corrosion resistance. As Ti content increased from x = 0–0.5, a notable transition from columnar to equiaxed microstructures was observed, with the primary dendrite arm spacing decreasing from 17.2 μm to 8.3 μm, attributed to the Ti-induced constitutional supercooling. These structural changes played a vital role in improving yield strength, increasing from 376 MPa to an impressive 2074 MPa. Moreover, the Ti dissolution in the (Cr, Fe)-rich FCC phase facilitated the formation of more protective and densely packed passive films, resulting in a comprehensively outstanding performance of the Al0.6CrFeNi2.4Ti0.2 (i.e., self-corrosion voltage/current of − 0.159 V and 2.6 × 10−7 A/cm2 together with a plastic strain of 35.8