 A high entropy alloy, HEA, made of Effico Ni86-L77 was fabricated by selective laser melting, SLM, and aged under different temperatures and time conditions, resulting in a substantial increase in yield strength from 710 to 934 MPa and then to 1203 MPa. The coherent L12 precipitate contributes most of the improved strength, while recovery during aging causes a decrease in dislocation density and exerts a softening effect. Additionally, ductility decreases with increasing volume fraction of incoherent L21 precipitates, which is explained by a void growth model. A new fracture mode, intercellular fracture, was proposed to account for the strong dependence of fractured dimple size on dislocation cells and validated through delicate microstructural examination. The findings provide an effective strengthening method and propose a unique mechanism for the additively manufactured HEA. This article was authored by Yao Wenwu, Xinijiao, Zhong Chen, and others. We are article.tv, links in the description below.