Effect of TiB ₂ Content on Crack Suppression Mechanisms and Microstructural Evolution of IN939 Superalloy Under Pulsed Laser Processing

High‐γ′ nickel‐based superalloy IN939 is highly susceptible to cracks during laser additive manufacturing, severely limiting its engineering applications. In this work, TiB ₂ /IN939 composites were fabricated via pulsed‐wave (PW) laser processing by incorporating TiB ₂ particles, and their effects on microstructural evolution, cracking behavior, and friction and wear performance were systematically investigated. The results show that under rapid solidification conditions, TiB ₂ particles promote heterogeneous nucleation, reducing the average grain size by approximately 16.82% and significantly weakening the continuity of columnar grains while shortening the interdendritic liquid film channels. The 2 wt.% TiB ₂ composite exhibits the lowest local strain level and optimal crack suppression efficiency. The synergistic effect of grain refinement and particle strengthening enhances grain boundary stability and load‐bearing capacity, effectively disrupting crack propagation paths. Furthermore, compared to pure IN939, this composite exhibits an overall superior wear resistance when assessed across both room‐temperature and high‐temperature conditions.