Impact of Aluminum Addition on Microstrain and Dislocation Density in CoCrFeMnNi High-Entropy Alloys

In this research, the influence of aluminum (Al) addition on the structural and mechanical properties of CoCrFeMnNi high-entropy alloys was investigated through the lens of solid-state physics. Utilizing vacuum arc melting for fabrication, the study examines the phase transformations, lattice distortions, and their correlation with material hardness. X-ray diffraction analysis reveals a 2.5% peak shift from 44.55° (face-centered cubic) to 45.66° (body-centered cubic), indicating a phase transition. This structural evolution is accompanied by a 142.7% increase in microstrain (from 1.44 x 10-5 to 3.48 x 10-5) and a 58.6% rise in dislocation density (from 4.06 x 107 to 6.44 x 107 cm-2), signifying enhanced lattice distortions. Consequently, the Vickers hardness improves by 178.3%, from 183.38 ± 5 to 510.59 ± 5 HV. The transition from face-centered phase to body-centered cubic phase, driven by lattice distortions and microstructural modifications, underscores the Al's pivotal role in optimizing HEA properties. These findings provide critical insights into the phase behavior and mechanical property enhancement, contributing to advances in the design and application of high-performance materials.