While extreme P-T conditions provide a vast landscape for material discovery, capturing these states at ambient conditions remains a formidable challenge. Here, we demonstrate the synthesis of a metastable dual-phase microstructure in ruthenium, governed by a bidirectional hcp-fcc transformation. Utilizing in situ high-energy X-ray diffraction within laser-heated diamond anvil cells, we identified the structural evolution, while HRTEM and ab initio molecular dynamics simulations elucidated the stabilization mechanisms of this quenched architecture. Our results reveal that a negative stacking fault energy facilitates the formation of a 3D interpenetrating hcp network that serves as a load-bearing skeleton, while the embedded untransformed fcc phase acts as a ductile filler for sustained dislocation activity. This synergistic microstructure effectively transcends the conventional strength–ductility trade-off. This work establishes defect-architectural engineering—rather than chemical alloying—as a primary stabilizer for metastable states in pure metals, providing a new strategy for designing high-performance structural materials under extreme conditions.
 

high temperature and high pressure,Microstructure,phase transition