Quantitative Analysis of γ′ and η Phase Evolution in a Ni-Based Superalloy Under Laser-Assisted Heat Treatment

This study investigates the microstructural evolution and mechanical behavior of a Ni-based superalloy subjected to combined heat treatment and laser processing. Special emphasis is placed on the quantitative analysis of γ′ Ni₃(Al,Ti) and η (Ni₃Ti) phase distributions using SEM-based statistical methods. OM/XRD were employed for initial structural and phase identification, followed by detailed microstructural characterization using SEM/EDS. The results reveal that γ′ precipitates exhibit a fine and uniform distribution with a high number density, whereas the η (Ni₃Ti) phase appears as relatively coarse and sparsely distributed particles. Statistical size distribution analysis demonstrates that processing parameters significantly influence precipitate morphology and phase stability. Laser treatment promotes redistribution of γ′ precipitates and suppresses η (Ni₃Ti) phase formation, resulting in improved microstructural homogeneity. Mechanical characterization shows a strong correlation between γ′ Ni₃(Al,Ti) phase refinement and enhanced hardness and tensile properties. Fractography analysis indicates predominantly ductile fracture behavior with microvoid coalescence. The findings provide a quantitative understanding of phase evolution and establish a microstructure property relationship for optimizing Ni-based superalloys through advanced processing techniques.