<p>A boron-aluminum composite diffusion layer was successfully prepared on the TA2 surface using ultrasonic surface shot peening (USSP) and low-temperature solid powder pack boron-aluminizing (B + Al). The surface morphology, phase composition, elemental distribution, mechanical properties, roughness, and tribological behavior of each modified layer were systematically investigated. XRD patterns reveal the presence of Al₃Ti, TiB₂, and TiB peaks in the B + Al composite layer. SEM and WDS results indicate the composite structure comprises an outer TiB₂ layer, TiB + Al₃Ti sublayer, Al₃Ti layer, and an inner diffusion layer. The surface hardness of this composite sample increased approximately fivefold compared to the substrate. Tribological testing indicates the composite diffusion layer exhibits the lowest and most stable coefficient of friction (~ 0.37). The worn scar surface appears smooth and flat, with a wear mechanism characterized by uniform plastic wear. The modified layer remains relatively intact, showing minimal material transfer to the counterface.</p>