Intermetallic Phase Formation in Non-Equiatomic High-Entropy Alloy Femnnialcrsic and Femnnialtisic Nanoparticles Synthesized Using Laser Ablation and Processing: The Synergistic Role of Silicon, Chromium, and Titanium

Abstract

This study reports synthesis and phase evolution of non-equiatomic high-entropy alloy (HEA) nanoparticles (NPs) using a two-step process. NPs were first syntheized via pulsed laser ablation using a picosecond laser, from two different compositions, FeMnNiAlCrSiC (HEA-Cr) and FeMnNiAlTiSiC (HEA-Ti), followed by laser-processing using a nanosecond laser. The investigation focused on phase evolution, elemental distribution, and structural transformations. Detailed analysis revealed that Si plays a crucial role in driving the intermetallic phase formation. HEA-Cr NPs exhibited a non-uniform elemental distribution, with Al being prominent towards the edges, and strong Fe-Ni and Fe-Si mixing was observed. Structural analysis confirmed the presence of BCC, B2, Fe5Si3, Cr5Si3, and γ-brass type phases, with post-processing enhancing Fe5Si3 and Cr5Si3 formation. In HEA-Ti system, replacing Cr with Ti, improved the uniformity of elemental distribution, which is attributted to Ti’s high miscibility with other constituent elements. The strong affinity of Ti for Si leads to the formation of Ti5Si3 type phases. Post-processing, the uniformity of the elemental distribution further enhanced along with the formation of Ti5Si3-type phases. In both HEA-Cr and HEA-Ti system, post-processing the HEA NPs (a mix of solid solution and intermetallic phases) transitioned to intermetallic HEA NPs. The thermodynamic calculations confirmed that post-processing favored intermetallic HEA NPs formation, which is attributed to laser-induced annealing effect. This work highlights the synergistic role of Si with Cr and Ti in tailoring phase composition and offers insights into laser-driven phase engineering in HEA NPs for advanced material design.

Keywords: High-entropy alloys, Laser Ablation, Laser
 Annealing, Nanoparticles, Intermetallics, Phase Modulation