通过激光立体成形得到了Inconel 718合金沉积态和固溶态试样,研究了时效温度及时效时间对δ相尺寸、形貌和体积分数的影响。结果表明,沉积态试样δ时效处理时,δ相首先在枝晶间的Laves相周围以短针状的形态析出,不形成长针状的穿晶δ相;固溶态试样δ时效处理时,在890 ℃下长时间时效处理可形成穿晶的δ相,而950 ℃下时效处理时δ相只在晶界处以短棒状析出。固溶态试样δ相析出的孕育期延长,且时效结束后形成的δ相体积分数较小。沉积态和固溶态试样中δ相的析出表观激活能分别为1917 kJ·mol ^-1和1867 kJ·mol ^-1。

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.