Dose and dose rate effects on the microstructural and mechanical stability of long-range ordered precipitates in Inconel 718

Nickel-based alloys offer exceptional mechanical properties and corrosion resistance for various applications in extreme environments such as high neutron flux, temperature, and stress. Precipitates, resulting from thermal treatments, increase the strength and creep resistance of these alloys. In this study, heavy ion irradiation is shown to destabilize the gamma ' and gamma'' precipitates in Inconel 718 nickel-based alloy by disordering and dissolution processes. Transmission electron microscopy and atom probe tomography reveal that the disordering and dissolution rates of the precipitates are proportional to both irradiation dose and dose rate. Irradiation induced disordering occurs at a higher rate than the dissolution. From analyzing the hardening contributions, microscale mechanical results suggest radiation-induced disordering is responsible for the majority of the softening response at low dose. In addition, low dose radiation-induced disordering results in strain localization and is believed to be the primary cause for the drastic degradation of uniform elongation and toughness in irradiated Inconel 718.

Automated summary

Nickel-based alloys have excellent mechanical properties and corrosion resistance, making them suitable for various applications in extreme environments. This study shows that heavy ion irradiation disrupts the precipitates in Inconel 718 nickel-based alloy through disordering and dissolution processes. The rate of disordering and dissolution of the precipitates is proportional to both irradiation dose and dose rate. Radiation-induced disordering occurs at a higher rate than dissolution. Microscale mechanical results suggest that radiation-induced disordering is responsible for the majority of the softening response at low dose. Low dose radiation-induced disordering also results in strain localization and is believed to be the primary cause for the drastic degradation of uniform elongation and toughness in irradiated Inconel 718.