Enhancement of mechanical and electrochemical properties of Al0.25CrCoFe1.25Ni1.25 high-entropy alloys by coating Ni-P amorphous films

The Al0.25CrCoFe1.25Ni1.25 high-entropy alloys (HEAs) are coated with Ni-P amorphous films with a thickness of 35 μm. The as-cast HEAs have a yielding strength of 52 MPa. In contrast, the yielding strength of coated HEAs exhibits over 130 MPa, with a 160% improvement. A considerable total tensile strain as high as about 50% is detected in the as cast and coated HEAs. In addition, Ni-P coatings have a stable passive characteristic and form a thick passive film, suggesting that Ni-P coatings provide an effective barrier against active dissolution process. The current Ni-P coated HEAs combine the excellent mechanical and electrochemical properties.