The Embrittlement and Toughening of Metallic Glasses from Nano-Crystallization
26 Pages Posted: 31 Oct 2018
Date Written: October 31, 2018
Metallic glasses with secondary crystalline phase have been reported to either enhance or degrade the global plasticity. Here we employed molecular dynamics simulation to investigate a generic glass-forming system, in which crystal-glass composites can be obtained via in-situ crystallization. Ex-situ composite samples were also constructed by embedding perfect crystals into monolithic glasses in order to delineate the precise influence of the composite microstructure. Our simulations demonstrate both the toughening and embrittlement due to nano-crystallization. The double-edge-sword role of nanocrystals is mainly controlled by elastic mismatch between the crystalline phase and the glass matrix. The effects of volume fraction and size of nanocrystals can be understood in the perspective of cumulative probability of shear bands formation and propagation being interfered by the presence of nanocrystals.
Keywords: Nanocomposites, nano-crystallization, embrittlement, toughening, fracture
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