Influence of Discontinuous Precipitation on Microhardness and Wear Resistance in (FeCoNi)86Al7Ti7 High-Entropy Alloy

Abstract

In this study, the effects of discontinuous precipitation, a process known to enhance mechanical properties in alloys, on the microstructure and mechanical properties of the (FeCoNi)₈₆Al₇Ti₇ high-entropy alloy (HEA) are investigated. Varying the aging temperatures leads to the formation of lamellar structures consisting of face-centered cubic (FCC) and body-centered cubic phases, which significantly influence the mechanical properties of the alloy. The aging treatments reveal an inverse relationship between temperature and microhardness, with values decreasing from 890 to 700 HV as the temperature rises from 550 to 650 °C. Despite this reduction, the alloy retains a high hardness level, suitable for wear-resistant applications. The best wear resistance is observed at 550 °C, with a wear rate as low as 8.45 ± 1.6 × 10⁻⁵ mm³ N⁻¹ m⁻¹. This is attributed to stacking faults and dislocations within the FCC lamellae, which enhance resistance to dislocation glide. In this study, the critical role of microstructural engineering in optimizing the properties of HEAs is highlighted, providing valuable insights for developing high-performance materials for specific engineering applications.