# Enhanced Wear and Corrosion Resistance of AlCoCrFeNiMoTi High-Entropy Alloy via B Addition by Laser Cladding

## TL;DR

Adding boron to a high-entropy alloy improves its wear and corrosion resistance through microstructural changes and passive film stability.

## Contribution

A boron microalloying strategy is introduced to enhance the multifunctional surface performance of high-entropy alloys.

## Key findings

- Boron addition preserves BCC and σ phases while promoting TiB2 formation and lattice distortion.
- Boron improves microhardness and wear resistance, with optimal performance at x = 1.
- Low boron content enhances passive film stability, but excessive TiB2 particles degrade it.

## Abstract

To address the synergistic degradation mechanisms in engineering service environments, we propose a boron microalloying strategy to enhance the multifunctional surface performance of AlCoCrFeNiMo-based high-entropy alloys. AlCoCrFeNiMoTiBx coatings (x = 0, 0.5, 1, and 1.5) were fabricated on Q235 steel substrates using laser cladding. The microstructure of the coatings was characterized using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), while their wear and corrosion resistance were evaluated through tribological and electrochemical tests. The key findings indicate that boron addition preserves the original body-centered cubic (BCC) and σ phases in the coating while promoting the in situ formation of TiB2, leading to lattice distortion. With increasing B content, the BCC phase becomes refined, and both the fraction and size of TiB2 particles increase. Boron incorporation improves the coating’s microhardness and wear resistance, with the highest wear resistance achieved at x = 1, where abrasive and oxidative wear predominate. At lower content (x = 0.5), B enhances the stability of the passive film and thereby improves corrosion resistance. In contrast, excessive formation of large TiB2 particles introduces defects into the passive film, accelerating its degradation.