Cr ₂ O ₃ ‐Mediated Phase Transformation and Microstructural Evolution in

ABSTRACT

Reducing the friction‐induced material loss while maintaining the functional response of shape‐memory alloy (SMA) coatings was essential for the resource‐efficient and durable high‐temperature service. In this study, Cr ₂ O ₃ ‐reinforced CuAlMnTi SMA coatings were fabricated by laser direct energy deposition (LDED), and the composition‐dependent relationships among the microstructural evolution, phase transformation and the high‐temperature tribological performance were systematically investigated. The results show that the introduction of Cr ₂ O ₃ particles promotes the grain refinement and regulates the phase constitution and transformation behavior of CuAlMnTi SMA matrix, increasing the coating hardness by 9%–44% relative to the substrate. The average coefficients of friction (COFs) and wear rates are decreased with the increase of Cr ₂ O ₃ content, and the minimal COF and wear rate reach 0.533 and 71.1 ± 3.6 μm ³ ·N ⁻¹ ·mm ⁻¹ , respectively, demonstrating the friction reduction and wear resistance. The dominant wear mechanisms include adhesive wear, abrasive wear and oxidative wear, which are suppressed by the uniformly distributed Cr ₂ O ₃ particles and protective oxide films. These findings establish the mechanistic relationship among the Cr ₂ O ₃ reinforcement, phase transformation and tribological response, providing the viable strategy for the resource‐efficient wear protection and extending the service of SMA‐coated smart structural components.

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