Suppressed precipitates dissolution and dislocation loop growth in laser shock peened Inconel 718

Abstract

Inconel 718 alloy is a critical candidate material for Gen-IV nuclear reactors. However, its high-temperature mechanical performance is compromised under irradiation due to irradiation softening and embrittlement, raising concerns about its service reliability in advanced reactors with higher neutron flux. This study reveals a notable suppression of irradiation-induced precipitate dissolution in the Inconel 718 alloy treated by laser shock peening (LSP). Compared to the untreated material, the LSP-treated alloy shows a 40.8% decrease in the precipitate dissolution rate and a retardation in the growth of dislocation loops under irradiation. Consequently, LSP significantly reduces the irradiation-induced hardness change by 26.7% relative to the untreated sample. Molecular dynamics simulations further reveal that the high-density dislocations introduced by LSP serve as the primary trap for irradiation-induced defects, while the compressive residual stress provides an auxiliary barrier to diffusion. This dual-mechanism effectively suppresses the dissolution of precipitates and the growth of dislocation loops, resulting in a remarkable enhancement in the overall irradiation performance of Inconel 718.