Effects of Ti content on microstructure, mechanical and magnetic properties of FeCoNiAl0.25Mn0.75Tix high entropy alloy

The effects of Ti content on the microstructure, mechanical and magnetic properties of FeCoNiAl0.25Mn0.75Tix (x = 0, 0.25, 0.5 and 0.75) high-entropy alloys were systematically investigated. The microstructure evolved from a single-phase face-centered cubic (FCC) structure for the Ti0 alloy to a dual-phase FCC + body-centered cubic (BCC) structure for the Ti0.25 and Ti0.5 alloys, and ultimately to a multiphase structure (FCC + BCC + intermetallic, IM) for the Ti0.75 alloy. This microstructural evolution significantly influenced the alloy’s properties. Hardness increased markedly from 136.82 HV3 (Ti0) to 486.52 HV3 (Ti0.75), accompanied by enhanced yield strength and tensile strength, though elongation decreased, indicating a shift from ductile to brittle fracture behavior. Meanwhile, the saturation magnetization peaks at 1.014 Tesla (T) for the Ti0.5 alloy, increasing from 0.233 T for Ti0 and subsequently decreasing to 0.795 T for Ti0.75 alloy. The coercive force reached a minimum of 58 A/m in the single-phase FCC structure (Ti0), stabilizes at 324.5 A/m when FCC and BCC phases are balanced (Ti0.5), and increases to 638.5 A/m in the Ti0.75 alloy. The Ti0.5 alloy, with a hardness of 357.45 HV3, saturation magnetization of 1.014 T, and coercive force of 324.5 A/m, exhibits a promising combination of soft magnetic properties and high hardness, suggesting potential for applications in soft magnetic components where magnetic performance and surface hardness are required.