Effects of aging and irradiation on Fe-Ni-Al alloy

To explore the effects of aging and irradiation on the formation of solute clusters, Fe-2.8Ni-2.0Al (at.%) alloys after solid-solution treatment were aged at 500 degrees C for 16 h and 32 h and irradiated with Ar ions to the fluence of 4 x 10(16) ions.cm(-2) at 290 degrees C, respectively. Transmission electron microscope and atom probe tomography were used to characterize the microstructure and solute atoms distribution. Results showed that B2-NiAl clusters were formed in aged alloys and the number density increased with time. The number density of clusters was 8.35 x 10(22) m(-3) after 32 h at 500 degrees C aging. However, high number density of dislocation loops and B2-FeNi clusters were found after irradiation at 290 degrees C. The number density of clusters reached to 3.61 x 10(23) m(-3). The nucleation of B2-NiAl clusters under aging is driven by the phase transform free energy with the lower mixing enthalpy of Ni and Al atoms, while the formation of B2-FeNi clusters is due to the combination of the interaction between dislocation loops and Ni solutes with the enhanced diffusion rate of Ni atoms due to supersaturated vacancy.

Automated summary

The aging process led to the formation of B2-NiAl clusters with increasing number density over time, while irradiation resulted in higher number density of B2-FeNi clusters in the alloys. The nucleation of clusters during aging is driven by the phase transform free energy, while the nucleation of clusters after irradiation is a result of the interaction between dislocation loops and Ni solutes with enhanced diffusion rate of Ni atoms.