Friction Stir Processing of Cold-Sprayed High-Entropy Alloy Particles Reinforced Aluminum Matrix Composites: Corrosion and Wear Properties

The high-entropy alloy particles reinforced 6061Al composite was prepared by cold spray (CS) and then modified by friction stir processing (FSP). The microstructure evolutions, corrosion, and wear behaviors of the composites were investigated. Results showed that numerous micro-pores and cracks were distributed in the Al matrix due to adiabatic shear instability and insufficient deformation of the deposited particles for CSed samples. The average size of uniformly distributed HEA particles was ~ 24 μm, and the geometric necessary dislocation (GND) density reached 17.1 × 10 15 m −2 due to large plastic deformation during CS. Comparatively, the micro-pores and cracks were eliminated, and many fragmented HEA particles dispersed in the Al matrix with an average size of ~ 4 μm for FSPed sample. Note that the GND density reduced to 9.8 × 10 15 m −2 due to dynamic recrystallization during FSP. The formation rate of the oxide film was gradually greater than that of the dissolution rate with the samples immersion in 3.5 wt% NaCl solution from 12 to 36 h, and the main corrosion mechanism was particle dissolution around micro-pores and pitting for CSed and FSPed samples, respectively. In the polarization process, the FSPed samples exhibited low corrosion tendency and high corrosion rate due to the dense and uniform microstructure, low GND density, and dispersed HEA particles. The FSPed samples had better wear resistance than the CSed samples at 25 °C and 200 °C. The dominant wear mechanisms of CSed and FSPed samples were abrasion at 25 °C, while the wear mechanisms of these samples were adhesion accompanied by abrasion at 200 °C. Graphical Abstract