Ductile-brittle transition of carbon alloyed Fe40Mn40Co10Cr10 high entropy alloys

The mechanical behavior of (Fe40Mn40Co10Cr10)100−xCx (x = 0, 2.2, 3.3 at.%) high entropy alloys (HEA) at various temperatures (298 K, 159 K and 77 K) was investigated. For Fe40Mn40Co10Cr10 HEA, the jointly activated twinning and martensitic phase transformation concurrently increase the strength and ductility at 77 K. In contrast, twinning and phase transformation gradually vanish as temperature decreases for carbon alloyed HEAs, resulting in ductile-brittle transition. Our findings indicate that the additional interstitial carbon atoms increase the f.c.c. phase stability, and inhibit the deformability of Fe40Mn40Co10Cr10 HEA at low temperature.