Acoustic emission spectra and statistics of dislocation movements in Fe₄₀Mn₄₀Co₁₀Cr₁₀ high entropy alloys

Abstract

The defining feature of high-entropy alloys (HEAs) is their unprecedented degree of compositional inhomogeneity which influences their dislocation movements. We demonstrate differences between a HEA (Fe40Mn40Co10Cr10) and a conventional solution alloy (316L stainless steel) using acoustic emission (AE) spectroscopy. AE measurements under tension show the coexistence of two avalanche processes in Fe40Mn40Co10Cr10 HEA, whereby one avalanche process relates to the movement of dislocations and the other to detwinning/twinning processes. These two avalanche processes exhibit two branches of the E ∼ A2 correlation. The dislocation movements in Fe40Mn40Co10Cr10 HEA show systematically longer durations compared with the equivalent dislocation movements in the 316L stainless steel and a bias toward faster waiting times for subsequent dislocation movements. The aftershock rate, as identified by the Omori law, is the same for the two materials.