The Chemical Environments Around Cu in Amorphous Fesibcunb Alloy

•Strong bonding is present in Cu-Si pair; while in the Cu-Cu and Cu-Nb pairs almost no bonding exists.•We further suggest that the addition of Cu in this quinary amorphous alloy is to promote FeSi cluster units to separate from FeB cluster units.•The Cu-centered cluster connections by one-atom-shared are favored in this quinary amorphous alloy.•The value of Bs is 1.28T at 300K, which is close to the experimental value.