Work-hardening crossover marks the loss of cellular hardening advantage in an additively manufactured Co-based superalloy

Cellular substructures can enhance work hardening in additively manufactured alloys, but this benefit is temperature limited. Here, laser powder bed-fused GH5188 in a cellular state (Cell) and a solution-treated reference (Free) were tensile tested at 350-750 °C. The Cell-Free work-hardening-rate difference, ΔΘ, remained positive up to 600 °C but became negative at 750 °C, bracketing a crossover between 600 and 750 °C. TEM revealed increasingly prominent planar faulting with temperature. The crossover therefore marks the upper limit of the additional Cell work-hardening advantage rather than disappearance of cellular morphology or strengthening.