Photo-Activated Growth and Metastable Phase Transition in Metallic Solid Solutions.

Laser processing in metals is versatile yet limited by its reliance in phase transformation through heating rather than electronic excitation due to their low absorptivity attributing from their highly ordered structures. Metastable states (i.e., surfaces, glasses, undercooled liquids), however, represent a unique platform, both energetically and structurally to enable energy landscape tuning through selective stimuli. Herein, we demonstrate this ansatz by exploiting thin passivating oxides to stabilize an undercooled state, followed by photo-perturbation of the near surface order to induce convective Marangoni flows, edge-coalescence and phase transition into a grown metastable solid bearing asymmetric composition between the near surface and core of the formed structure. The self-eliminating nature of the process creates a perfectly contained system which can maintain high relaxation energy barrier and deep metastable state for extended period of time. This article is protected by copyright. All rights reserved.