Determination of microstructural parameters in AlCrFeCoNi high-entropy alloy coatings by Williamson-Hall analysis

• Mechanically alloyed powders exhibit FCC + BCC (A2/B2) dual-phase structure • APS processing stabilizes a predominantly FCC (A1) phase in AlCrFeCoNi HEA coatings • Williamson–Hall analysis was applied to the dominant FCC phase to extract crystallite size, micro-strain, and dislocation density AlCrFeCoNi high-entropy alloy (HEA) coatings were deposited on 316L stainless steel by atmospheric plasma spraying (APS) technique. The high energy ball-milling method with different milling duration was used to prepare the AlCrFeCoNi powder feedstock. FESEM and XRD analyses revealed a dual-phase structure in the mechanically alloyed powders, consisting of FCC and BCC (A2/B2) phases. After atmospheric plasma spraying, the coatings exhibited a predominantly FCC (A1) solid-solution structure with minor residual BCC/B2 features. Crystallite size and lattice micro-strain were then determined using the Williamson-Hall (W-H) method using Uniform Deformation Model (UDM), Uniform Stress Deformation Model (USDM). UDM gave an average crystallite size of 45 ± 9 nm and micro-strain of 0.42 ± 0.05% for as-sprayed coatings. USDM confirmed residual micro-strain in the coating structure. Dislocation density of AlCrFeCoNi HEA coatings ranged from 1.6–3.6 × 10 15 m −2 , arising from powder preparation history, rapid solidification and particle impact deformation.