Researchers have developed an innovative approach to designing fatigue-resistant multi-principal element alloys (MPEAs), opening new possibilities for their application and further exploration.

MPEAs are a novel class of materials composed of multiple principal elements rather than just one or two. Traditionally, it is believed that increasing strength through compositional modifications or the addition of brittle phases adversely affects fatigue life.

Challenging these notions, Dr. Ankur Chauhan and his team from the Department of Materials Engineering, Indian Institute of Science (IISc) Bangalore, systematically explored the role of two critical microstructural features in enhancing the low-cycle fatigue (LCF) performance of alloys in the Cr-Mn-Fe-Co-Ni system.

By adjusting the Cr/Ni ratio, they synthesized two single-phase face-centered cubic (FCC) MPEAs with distinct SFEs. The low-SFE alloy exhibited 10–20% higher cyclic strength than the high-SFE alloy while maintaining a comparable fatigue life. This improvement is attributed to the delayed evolution of dislocation substructures and a lower crack propagation rate in the low-SFE alloy compared to the high-SFE alloy.

Additionally, the team developed a dual-phase alloy that demonstrated a 50–65% increase in cyclic strength over the single-phase low-SFE alloy while maintaining a similar fatigue life.

This enhanced fatigue resistance is attributed to finer dislocation structures, higher back stresses from reduced grain size, crack deflection by brittle σ-precipitates, and extensive deformation twinning around fatigue cracks, which complement slip activity and slow crack propagation.

These findings provide a framework for designing both single-phase and dual-phase fatigue-resistant MPEAs, with implications for structural applications. By offering deeper insights into deformation and damage mechanisms, this work advances the understanding of how SFE and secondary brittle phases influence the mechanical properties of MPEAs, paving the way for further research into complex alloy systems. This work is supported by the Anusandhan National Research Foundation, a statutory body under the Government of India.

 

****

NKR/PSM

(Release ID: 2108794) Visitor Counter : 734