Data-driven interpretation of wear mechanisms in rare-earth-modified FeNiCrMoAl high-entropy alloys via hybrid anomaly analytics

Understanding transient frictional instabilities is essential for interpreting wear mechanisms in high-entropy alloys, yet classical tribological metrics provide only averaged responses that mask short-lived surface events. This study addresses this gap by integrating hybrid anomaly analytics with conventional tribological testing to evaluate the dry sliding behaviour of FeNiCrMoAl-based high-entropy alloys modified with Ce and Nd. Seven alloy compositions were produced by vacuum induction melting and tested under identical reciprocating conditions, while an Arduino-based load-cell system continuously recorded more than 25,000 friction data points per test. A combined Z-Score and IQR method was applied to quantify local frictional spikes associated with asperity fracture, third-body generation, and tribo-oxide instability. Alloys containing 20 wt.% Ce or Nd (HEA3 and HEA6) exhibited the lowest wear rates and the most stable Friction Coefficient (COF) profiles, accompanied by smooth, uniform wear tracks. In contrast, RE-free and low-RE alloys showed late-stage anomaly accumulation and severe ploughing or adhesive wear. These findings demonstrate that anomaly-density mapping provides mechanistic insight into frictional stability that cannot be captured by average COF or wear rate alone, offering a quantitative framework for designing high-entropy alloys with improved tribological performance.