Effect of solid-solution treatment on microstructure and impact properties of solid-solution + aged UNS N07718  alloy[/%:0.03C

52.5Ni

18.0Cr

3.0Mo

5.0(Nb+Ta)

0.90Ti

0.50Al] are investigated.After960℃ solid-solution + aging treatment

the δ phase diffusely distributes on the grain boundaries and in the grains

and the grains are relatively uniform and fine with impact energy 17J.After1000℃+960℃ solid-solution+aging treatment

the size of δ phase distributed on the grain boundaries becomes larger

and the grain size is slightly increased.After1010℃+960℃ solid-solution aging treatment

the phase& are dissolved

and only a little of δphase is located at the grain boundaries

while the grain size is increased evidently.After1020℃+960℃ solid-solution+aging treatment

the granular δ phases are disappeared.After1010℃+960℃solid-solution+agingtreatment

the impact energy of sample is 43J and a 150% increase in the impact energy

compared with 960℃ aged in addition

the fracture morphologies of the sample surface exhibit a number of dimples obviously.