Inconel 718 (IN718) superalloy is a well-established material for the application of aircraft engine and power generator due to its excellent performance at high temperatures. The outstanding mechanical properties of IN718 are largely determined by the precipitates. Here, we investigated the precipitation behaviors and the corresponding mechanical properties of the heat-treated gradient IN718 alloy. The microscopy studies reveal that high-density hexagonal η phase with chemistry of Ni₃(Al,Ti,Nb) formed in the nanograined IN718 alloy after annealing at 700 °C. The compressive stress introduced during severe plastic deformation may have prohibited the formation of γ” phase while accelerated the precipitation of γ’ phase, consequently favoring the precipitation of η phase. The corresponding evolution of mechanical behavior of gradient IN718 alloy is investigated.

Inconel 718（IN718）高温合金由于其在高温下的出色性能，是一种用于飞机发动机和发电机的成熟材料。IN718优异的机械性能在很大程度上取决于沉淀物。在这里，我们研究了热处理梯度IN718合金的析出行为和相应的力学性能。显微镜研究表明，高密度六方η相具有Ni _3的化学性质在700°C退火后，在纳米晶粒IN718合金中形成（Al，Ti，Nb）。在剧烈的塑性变形过程中引入的压应力可能阻止了γ”相的形成，同时加速了γ'相的析出，因此有利于η相的析出。研究了梯度IN718合金力学行为的相应演变。