Effect of laser power on the microstructure and corrosion resistance of AlCoCrFeNi high-entropy alloy cladding layers
摘要
To improve the corrosion resistance of the Q235 steel, AlCoCrFeNi high-entropy alloy (HEA) cladding layers were fabricated by using laser powers of 700 W, 800 W and 900 W. The microstructure, dilution rate, phase, elemental distribution and corrosion behavior of three cladding layers were analyzed through scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and electrochemical testing. Results show that as the laser power increased from 700 to 900 W, the thickness increased from 990 μm to 1280 μm, and the dilution rate rose from 8.7% to 11.5%. The structural uniformity of the layer improved and the defects eliminated with increasing laser power. Three cladding layers all consisted of a single BCC solid solution phase, regardless of the laser power. However, Fe content increased with increasing power, leading to a reduction in the mixing entropy from 1.59 R to 1.52 R. The corrosion current density decreased from 10.117 × 10–5 A·cm−2 to 3.936 × 10–5 A·cm−2 and then increased to 5.402 × 10–5 A·cm−2, when the laser power increased from 700 to 900 W. Therefore, the uniform corrosion resistance of the layer fabricated with laser power of 800 W in the case was superior to that of the other two cladding layers.