Deciphering the role of solidification cell structure in the hydrogen embrittlement of CoCrFeNi medium-entropy alloy fabricated by laser-powder bed fusion: Insights from annealing treatments

The role of solidification cell structure in hydrogen embrittlement (HE) in laser-powder bed fusion fabricated CoCrFeNi medium-entropy alloy is investigated by comparing as-built and annealed conditions. Annealing at 1100 degrees C dissolves the cell structure and induces partial recrystallization. This slightly reduced the strength but significantly improves HE resistance by suppressing hydrogen-assisted intergranular cracking. The results are discussed in terms of the changes in hydrogen trapping/diffusion behavior and deformation behavior upon removal of cell structure, as investigated through thermal desorption spectroscopy, Ag decoration, and digital image correlation technique.