Intermittent cluster dynamics and temporal fractional diffusion in a bulk metallic glass.

Glassy solids evolve towards lower-energy structural states by physical aging. This can be characterized by structural relaxation times, the assessment of which is essential for understanding the glass' time-dependent property changes. Conducted over short times, a continuous increase of relaxation times with time is seen, suggesting a time-dependent dissipative transport mechanism.

Entering a New Dimension in Powder Processing for Advanced Ceramics Shaping.

Filigree structures can be manufactured via two-photon polymerization (2PP) operating in the regime of nonlinear light absorption. For the first time, it is possible to apply this technique to the powder processing of ceramic structures with a feature size in the range of the critical defect sizes responsible for brittle fracture and, thus, affecting fracture toughness of high-performance ceramics. In this way, tailoring of advanced properties can be achieved already in the shaping process.

Applied-force oscillations in avalanche dynamics.

Until now most studies of discrete plasticity have focused on systems that are assumed to be driven by a monotonically increasing force; in many real systems, however, the driving force includes damped oscillations or oscillations induced by the propagation of discrete events or "slip avalanches." In both cases, these oscillations may obscure the true dynamics. Here we effectively consider both cases by investigating the effects of damped oscillations in the external driving force on avalanche dynamics.

Stress breaks universal aging behavior in a metallic glass.

Numerous disordered materials display a monotonous slowing down in their internal dynamics with age. In the case of metallic glasses, this general behavior across different temperatures and alloys has been used to establish an empirical universal superposition principle of time, waiting time, and temperature. Here we demonstrate that the application of a mechanical stress within the elastic regime breaks this universality.

Strain induced fragility transition in metallic glass.

Relaxation dynamics are the central topic in glassy physics. Recently, there is an emerging view that mechanical strain plays a similar role as temperature in altering the relaxation dynamics. Here, we report that mechanical strain in a model metallic glass modulates the relaxation dynamics in unexpected ways.

Room temperature homogeneous ductility of micrometer-sized metallic glass.

Homogeneous ductile flow of metallic glasses is observed at the micrometer scale. It is shown that this unusual deformation mode of an otherwise brittle material depends on both specimen size and applied loading rate. The results are explained by intrinsic length-scale effects of nanometer-sized defects, and provide a rationale for the long term debated brittle-to-ductile transition of amorphous metals.

Ultrahigh strength of dislocation-free Ni3Al nanocubes.

Individual Ni(3) Al nanocubes under pressure are investigated by comparing the compressive strength of both dislocation-free and irradiated Ni(3) Al nanocubes. The results are dicussed in light of the size-dependent and size-independent strength of face-centered cubic (fcc) nanocrystals in the framework of dislocation nucleation at free surfaces. This study sheds more light on the understanding of fundamental deformation mechanisms and size-affected strength in dislocation-free metallic nanocrystals.

Time-resolved Laue diffraction of deforming micropillars.

We demonstrate real-time resolved white beam Laue diffraction during compression of micron-sized focused ion beam milled single crystals Au pillars, revealing the dynamical correlation between microstructure and plasticity. The evolution of the Laue patterns of the Au pillars demonstrates the occurrence of crystal rotation and strengthening is explained by plasticity starting on a slip system that is geometrically not predicted but selected because of the character of the preexisting strain gradient.