Abstract
The discovery of quasicrystals three decades ago unveiled a class of matter that exhibits long-range order but lacks translational periodicity. Owing to their unique structures, quasicrystals possess many unusual properties. However, a well-known bottleneck that impedes their widespread application is their intrinsic brittleness: plastic deformation has been found to only be possible at high temperatures or under hydrostatic pressures, and their deformation mechanism at low temperatures is still unclear. Here, we report that typically brittle quasicrystals can exhibit remarkable ductility of over 50% strains and high strengths of ∼4.5 GPa at room temperature and sub-micrometer scales. In contrast to the generally accepted dominant deformation mechanism in quasicrystals—dislocation climb, our observation suggests that dislocation glide may govern plasticity under high-stress and low-temperature conditions. The ability to plastically deform quasicrystals at room temperature should lead to an improved understanding of their deformation mechanism and application in small-scale devices.
Highlights
The discovery of quasicrystals three decades ago unveiled a class of matter that exhibits long-range order but lacks translational periodicity
A great variety of quasicrystals have been synthesized[7,8], and some have even been discovered in nature[9], and found to be technologically interesting[10,11,12,13] and useful[14], only few of them can be found in applications so far, mainly limited by their poor ductility and formability at room temperature
Studies of the plastic deformation of quasicrystals focused on an grown icosahedral quasicrystal, i-Al–Pd–Mn, in the high-temperature regime above B600 °C (B70% of its melting temperature). These studies demonstrated that the plastic deformation of i-Al–Pd–Mn was dominated by dislocation climb—with the Burgers vector out of the plane of dislocation motion, rather than dislocation glide—with the Burgers vector restricted in the plane of dislocation motion[15]
Summary
The discovery of quasicrystals three decades ago unveiled a class of matter that exhibits long-range order but lacks translational periodicity. There are some hints that the glide motion may be possible in lowtemperature conditions as suggested by numerical simulations[17] or under high hydrostatic pressures[18], the required stress to activate glide is extremely high, on the order of 1/10 of its shear modulus—a stress level generally leading to fracture without showing any ductility. It has been a long-standing question concerning the deformation mechanism in quasicrystals at room temperature. We suggest that dislocation glide may control the plastic deformation of quasicrystals at room temperature and attempt to shed light on the underlying deformation mechanism in the low-temperature regime
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