Abnormal precipitation behavior of γ'′ phase at twin boundaries of LPBF Inconel 718 and its effect on mechanical properties

It is a promising way to prepare nickel-based superalloy components by additive manufacturing technology. This study aims to describe the detection of an unexpected precipitation mechanism of gamma '' phase at twin boundary in the context of Inconel 718 superalloy by Laser Powder Bed Fusion (LPBF). Innovative methods are introduced in this research to examine the growth of twins and their interaction with precipitates in Inconel 718 alloy. The elucidation of twin evolution, gamma '' precipitation, and their interplay is successfully achieved through the examination of the dimensions of gamma '' precipitation, the inaccuracies in grain boundary orientation, and the atomic dimensions of the twin boundary. The objective of this study is to provide a comprehensive understanding of the atomic-level physical processes that contribute to the unusual precipitation behavior observed in gamma ''-strengthened Ni-based superalloys. Additionally, we aim to investigate the impact of this behavior on the mechanical properties of these alloys at high temperatures. Furthermore, we propose a practical methodology for modifying the composite configuration of gamma ''- twin boundaries (TBs) to enhance the thermal characteristics of nickel-based alloys.