Slurry Erosion Resistance of Laser Clad NiCoCrFeAl3 High-Entropy Alloy Coatings

Abstract

The slurry erosion resistance of laser-clad NiCoFeCrAl3 high-entropy alloy (HEA) coating was investigated by using a jet erosion testing machine. When the impingement angle increased from 15° to 90°, the volume loss of the HEA coating was accelerated firstly and then followed with a slight deceleration. The largest volume loss of this HEA coating was 4.1 mm3, which was acquired at a 45° impingement angle after a 30-min erosion time with a 15 wt% SiO2 particles (350–600 μm) at an impact velocity of 13 m s−1. Under the same erosion situation, the volume loss of 17-7 PH stainless steel was 5.4 mm3, which means that the HEA coating possesses better erosion resistance under this situation. Annealing treatment is beneficial to improve the erosion resistance of HEA coatings. The 950°C annealed HEA coating had the best erosion resistance because the intermetallic compound Cr3Ni2 was precipitated from the matrix and the volume loss was reduced to 3.5 mm3 at a 45° impingement angle. The worn surface morphologies of HEA coatings were characterized by grooves, ploughing marks, and a small quantity of brittle fractures, which suggests that plastic deformation and abrasive wear were the predominant mechanisms in the slurry erosion of the HEA coatings.