<p>This study investigated the effect of adding Ti₃AlC₂ to composite solders consisting of Sn-58Bi-0.075GNSs. Different weight percentages (x = 0 wt.%, 0.25 wt.%, 0.5 wt.%, 0.75 wt.%, and 1.0 wt.%) of Ti₃AlC₂ were incorporated into the solder composites. The results showed that adding 0.5 wt.% Ti₃AlC₂ led to the most significant grain size refinement, reducing the average Bi phase intercept length by 55% compared to the Sn-58Bi-0.075GNSs solder. Ti₃AlC₂ acted as a nucleation site for the Bi-rich phase during solder solidification, preventing coarsening. It also formed a second phase along the grain boundaries, enhancing both grain refinement-strengthening and dispersion-strengthening mechanisms. Furthermore, the addition of 0.5 wt.% Ti₃AlC₂ resulted in the highest solder hardness, which was 6.2% greater than that of the Sn-58Bi-0.075GNSs solder. The Sn-58Bi-0.075GNSs-0.5Ti₃AlC₂ composite exhibited superior corrosion resistance, forming a dense passive film on the corroded surface.</p>