激光立体成形Inconel 718镍基高温合金δ相析出规律

The as-deposited and solution-treated Inconel 718 superalloy samples are fabricated by laser solid forming, and the influences of aging temperature and aging time on the size, morphology, and volume fraction of δ phases are investigated. The results show that as for the aging treatment of as-deposited samples, the δ phases precipitate around the interdendritic Laves phases with a short needle pattern, and there are no δ phases throughout grains with a long needle pattern. In contrast, as for a long time δ aging treatment of solution-treated samples, there occur δ phases throughout grains with a long needle pattern at 890℃, while for the aging treatment at 950℃, only the short-bar-like δ phases precipitate at grain boundaries. In addition, the incubation time of δ phase precipitation elongates, while the volume fraction of δ phases formed after aging treatment decreases. The apparent activation energies of δ phase precipitation for the as-deposited and solution-treated samples are 1917 kJ•mol^-1 and 1867 kJ•mol^-1, respectively.