In the literature, many studies have reported Ti, Ag, and Ta significantly improve the thermal stability of nanocrystalline NC-W for high-temperature applications. However, their segregation behavior and impact on the mechanical properties of NC-W remain poorly understood. This study investigates the segregation behavior and its effects on the mechanical properties of W-M binary alloys (where M represents Ti, Ag, or Ta). Advanced transmission electron microscopy techniques and atomistic modeling are utilized for a comprehensive analysis. After high-temperature annealing, distinct behaviors are observed for each alloying element. Ti and Ag exhibit heterogeneous segregation in NC-W, resulting in solute-depleted/enriched grain boundaries (GBs). Conversely, Ta atoms form a solid solution without forming clusters. Hybrid Monte Carlo (MC)/molecular dynamics (MD) simulations support and elucidate these …