Two kinds of high entropy alloys

CrCuFeMnNi and CoCrCuFeMnNi

were prepared by powder metallurgy. The atmospheric oxidation weight gain of the alloys was measured at 800 ℃. The phases of oxide and morphology of oxidation section were analyzed by X-ray diffraction and scanning electron microscopy

respectively. The atmospheric oxidation behavior of both alloys was discussed. The results indicate that the atmospheric oxidation kinetic curves of the alloys approximately follow the parabolic law. At the initial stage of oxidation

the oxidation weight gain of each alloy is faster

and slows down with the increase of oxidation time. In the rapid oxidation stage

the K

P

values of CrCuFeMnNi and CoCrCuFeMnNi alloys reach 6.64×10

-11

g

2

·cm

-4

·s

-1

and 3.55×10

-11

g

2

·cm

-4

·s

-1

respectively. In the slow oxidation stage

the K

P

values of the two alloys are 6.05×10

-12

g

2

·cm

-4

·s

-1

and 2.02×10

-11

g

2

·cm

-4

·s

-1

respectively

indicating that the oxidation resistance of the Co-free alloy is better. The oxidation products of the alloys are mainly Mn

4

O

3

Mn

3

O

2

and Cr

2

O

3

. After oxidation

a dense Cr

2

O

3

film is formed between the substrate and the oxide layer

which inhibits the oxidation rate of the inner layer and enhances the oxidation resistance of the Co-free alloy. The oxidation mechanism of the alloys is dominated by selective oxidation.