Experimental investigation of minor Si addition on AlNiYCo multi-principal element alloy: Microstructural characterization, thermal stability and corrosion resistance

High-performance multi-principal element alloys are regarded as novel structural and functional materials and also have attracted extensive research interests in academia as well as industry. In order to develop outstanding anti-corrosion and high-microhardness multi-principal element alloys with superior thermal stability, on the basis of our previous study, the effects of minor Si addition on the microstructure, thermal stability and corrosion resistance of (Al1/3Ni1/3Y1/3)92Co8 multi-principal element alloy were investigated in this current research. It was revealed that all types of as-quenched Si-containing alloy ribbons prepared by melt-spinning method could remain the homogeneous amorphous structures and their crystallization onset temperatures were over 760 K at the heating rate of 20 K/min. The average microhardness value of each specimen was more than 498 HV0.1 as well. The average roughness and the root mean square roughness of these studied metallic ribbons exhibited a roughness of 0.20 nm and 0.27 nm or below. When the Si content elevated from 0.5 to 4 at.%, it gave rise to a increase of pitting potential from −0.222 VSCE of the (Al1/3Ni1/3Y1/3)91.5Co8Si0.5 to −0.207 VSCE of the (Al1/3Ni1/3Y1/3)89Co8Si3 and -0.205 VSCE of the (Al1/3Ni1/3Y1/3)88Co20Si4 glassy alloy ribbons, which can be comparable to that of Al86Ni7Y4.5Co1La1.5 metallic glass ribbons by and large. The alloy ribbons with 3 at.% Si exhibited the outstanding anti-corrosion property in 3.5 wt% NaCl solution since it owned the most positive pitting corrosion potential and the widest overpotential region simultaneously compared with the other alloy ribbons. Therefore, it is supposed that adding minor Si element into (Al1/3Ni1/3Y1/3)92Co8 alloy can promote the ability for resisting pitting corrosion. This research work not only further verifies the available formation of amorphous state by minor Si addition, but also sheds light on the role of Si on thermal stability and anti-corrosion performance of AlNiYCo multi-principal element alloy.