Comparing the formation, properties and structure between Fe20Co20Ni20Cr20(P0.45B0.2C0.35)20 high-entropy metallic glass and the predecessor Fe75Cr5P9B4C7 metallic glass

Abstract

In present work, formation, properties and local structure features between novel Fe20Co20Ni20Cr20(P0.45B0.2C0.35)20 high-entropy metallic glass (HEMG) and the predecessor Fe75Cr5P9B4C7 metallic glass (MG) were thoroughly characterized by experiments and ab-initio molecular dynamics (AIMD) simulation. Compared with predecessor MG, the HEMG possesses a higher thermal stability of supercooled liquid with wider supercooled liquid region of 57 K, superior corrosion resistance with higher corrosion potential, lower corrosion and passive current density along with wider passive region in 3 wt.% NaCl solution. Additionally, the HEMG possesses a paramagnetic feature with low magnetization of only 9.38 emu·g−1, while predecessor MG possesses a good soft-magnetic property with a high saturation magnetization of 115.16 emu·g−1. The corresponding local structure differences deriving from AIMD simulation exhibit that the HEMG possesses a higher content of icosahedra-like structures (with bond pair indexes (BPIs) of 1551, 1541 and 1431) and Voronoi polyhedra (VPs) with relative smaller coordination numbers (8, 9, 11, 12 and 13), lower content of crystal-type structures (with BPIs of 1421, 1422, 1441 and 1661) and VPs with larger coordination numbers (15 and 16) compared with predecessor MG. These results show that the formation, properties and local structures can be visibly changed after present high-entropy alloying by similar solvent elements Co, Ni and Cr equiatomic substitution of Fe in predecessor MG. Additionally, both alloys possess dominant VPs with coordination numbers from 12 to 15 and good ductility without fracture as bent by 180°.