Mechanically driven disorder and phase transformations in alloys

Abstract

Crystal to glass transition under mechanical loading occurs in a wide range of natural and artificial events, including meteorite impact, shock explosion, and mechanical alloying. To investigate the atomic mechanisms, we carried out a series of tensile tests with the strain rates ranging from 108 to 1012 1/s applied to a multicomponent alloy. Our molecular dynamics simulation reveals that the model material undergoes a crystal-to-glass transition with the amount of the transformed phase determined by both the strain rate and applied strain. We observed two different atomistic mechanisms, both of which are closely connected to the state and kinetics of the crystal dislocations: Below 1011 1/s, the random stress of the defects jams the atomic displacements and causes heterogeneous amorphization, resulting in a first-order like transition; and at and above 1011 1/s, the fast deformation leaves no time for dislocation formation and propagation. The atomic displacement becomes localized on the scale of an atomic spacing, which destabilizes the crystal homogeneously and makes the transition appear continuous. The difference in the characteristics of the crystal-to-glass transformation is the direct manifestation of the atomic mechanisms revealed here.

Keywords

Affiliated Institutions

• VSL Dutch Metrology Institute NL
• University of Amsterdam NL

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