Cu

0.3

Cr

2

Fe

2

Ni

3

Mn

2

Nb

x

high-entropy alloys were prepared by arc melting process. The phase composition

microstructure

element distribution

hardness and acid corrosion resistance of the alloys were investigated by X-ray diffraction

scanning electron microscopy

microhardness tester and immersion corrosion test. The results reveal that when x=0 or x=0.2

alloys are composed of a single FCC solid solution phase

while the alloy is composed of FCC+Laves phases when x=0.4. The dendritic regions of all alloys are characterized by Cr-Fe-rich FCC phase regions. When x=0 or x=0.2

interdendritic regions of alloys are Cu-Mn-rich FCC phase regions and Nb-Ni-Mn-rich FCC phase regions

respectively

while that of alloy is Nb-Ni-Fe-rich Laves phase region when x=0.4.When x=0

the microhardness of alloy is lower

which is about 127 HV

and that of alloy is 203 HV when x=0.4

which is attributed to the solid solution strengthening of Nb element and the precipitation strengthening of Laves phase. In 2% HNO

3

solution

the immersion corrosion rate of the alloys is increased firstly and then decreased with the increase of Nb content. Due to reduction of element segregation degree

and desirable corrosion resistance of formed Laves phase

the alloy exhibits optimal acid corrosion resistance

which is still weaker than that of 1 Cr18 Ni9 Ti stainless steel.