Phase Transition Mechanism and Mechanical Properties of AlCrFe2Ni2 High‐Entropy Alloys with Changes in the Applied Carbon Content

Abstract

To understand the effect of carbon addition on dual‐phase high‐entropy alloys (HEAs), the mechanism of phase transition and mechanical properties of AlCrFe2Ni2Cx (x = 0, 0.06, 0.12, 0.18, 0.24) are investigated systematically. The results show that carbon addition induced the growth and aggregate of disordered noodle‐like face‐centered cubic (FCC) phases. The volume fraction of the FCC phase increases from 33.2% to 51.2% as the C content increases. The Al and Ni in the alloys are segregated at the phase boundaries. Disappearance of the spinodal decomposition structure compose of a disordered body‐centered cubic (BCC) structure and an ordered BCC structure (B2). The BCC phase transform into a spherical B2 phase with increasing C content. The experimental mechanical properties show that the yield strength of the HEAs is closely related to the volume fraction of BCC phase as the C content increases. The ε phase (Cr, C carbonization) precipitate in an FCC phase when the C content is above 2.0 at%. The hardness of the HEAs increases from 310 to 357 HV as the C content increases. The compressive strength and the fracture strain of the alloy decreases as the C content increases.