Ultrastrong Nanocrystalline Inconel 718 Fabricated by Powder High-Pressure Torsion and Annealing

In this study, bulk nanocrystalline material is fabricated from Inconel 718 powder through a process of powder high-pressure torsion (HPT) and subsequent annealing heat treatment. Numerous dislocations generated during the powder HPT process successfully produced bulk Inconel 718 with nanocrystalline grains during the post-annealing treatment. In addition, the Inconel 718 exhibited additional strengthening contributions such as dislocation strengthening by high pre-existing dislocation density and precipitation strengthening from randomly distributed precipitates. As a result of these strengthening effects, the Inconel 718 showed ultrastrong yield strength of 1.40 GPa and ultimate tensile strength of 1.53 GPa. Although the elongation of 12.0% did not indicate good ductility, the proposed Inconel 718 boasted improved mechanical properties compared to previous studies of Inconel 718 fabricated by various processing methods. The prepared Inconel 718 and its fabrication technique suggest the potential for manufacturing ultrahigh-strength bulk nanocrystalline materials not only for Inconel 718 but also for various metallic materials using powder metallurgy. Bulk nanocrystalline material was fabricated from Inconel 718 powder through powder high-pressure torsion (HPT) and subsequent annealing heat treatment. Due to the combined contributions of grain boundary strengthening, precipitation strengthening, and dislocation strengthening, the prepared Inconel 718 achieved ultrastrong yield strength and ultimate tensile strength of 1.40 and 1.53 GPa, respectively.image (c) 2024 WILEY-VCH GmbH