This study explores the erosion characteristics of 3D-printed Scalmalloy, an advanced aluminum–magnesium–scandium alloy, through a comprehensive investigation of varied process parameters. The erosion behavior was quantified through careful measurement of material loss, while the morphological changes on the surface were analyzed using scanning electron microscope (SEM) analysis. As the discharge of erodent increases, the kinetic energy of the particles is heightened, leading to augmented material removal and subsequently causing elevated erosion rates on the workpiece. An increase in the nozzle angle, the perpendicular force exerted by the particles, known as the normal force, decreases, while the parallel force, referred to as the tangential force, increases. The erosion rate increased from 30° to 45° due to increasing sliding wear, although it plateaued at 45° and 60° before falling at higher angles. According to the connection, the rate of erosion rose rapidly up to 60 m/s, plateaued between 60 and 120 m/s, and then increased marginally over 120 m/s. The rise in erosion rate from 6.33E-05 to 7.97E-05 (6.3–8%) with increased discharge is attributed to stronger impact forces and more particle interactions, resulting in greater material removal. The drop-in erosion rate between 325 and 350 °C indicates that higher ductility at elevated temperatures reduces adhesion and improves fracture resistance. At 25 m/s velocity and 60° angle, alumina particles likely strike with sufficient force to exceed the fracture toughness of Scalmalloy at 325 °C.