A new approach to grain boundary engineering for nanocrystalline materials

• Shigeaki Kobayashi,
• Sadahiro Tsurekawa and
• Tadao Watanabe

Beilstein J. Nanotechnol. 2016, 7, 1829–1849, doi:10.3762/bjnano.7.176

• shear band. They nucleate at the deformation ledge produced at sliding random boundaries by the interaction with PSBs or triple junctions of high connectivity of random boundaries, as discussed in detail by Watanabe [120]. In fatigue fracture of nanocrystalline Ni, Kumar et al. [121] also reported the

Deformation-driven catalysis of nanocrystallization in amorphous Al alloys

• Rainer J. Hebert,
• John H. Perepezko,
• Harald Rösner and
• Gerhard Wilde

Beilstein J. Nanotechnol. 2016, 7, 1428–1433, doi:10.3762/bjnano.7.134

• crystallization temperature of undeformed ribbons. Keywords: amorphous alloy; annealing; cold-rolling; nanocrystal; shear-band; Findings Crystallization reactions in metallic glasses have been extensively studied due to the beneficial effect of nanocrystal dispersions on mechanical [1][2][3][4] and magnetic

• bands [39]. This letter yields further evidence that intense deformation does indeed affect the regions between shear bands and even promotes crystallization in non-shear band regions. Melt-spun amorphous Al88Y7Fe5 alloy was annealed in a TAM microcalorimeter (TA Instruments) at 60 °C, i.e., about 200 K

• Figure 6 shows that nanocrystals have developed homogeneously throughout the deformed sample rather than in localized regions. Shear bands are not detected in the dark-field TEM images after the annealing. With shear band distances of the order of micrometers [41] and good contrast between shear bands

Lower nanometer-scale size limit for the deformation of a metallic glass by shear transformations revealed by quantitative AFM indentation

• Arnaud Caron and
• Roland Bennewitz

Beilstein J. Nanotechnol. 2015, 6, 1721–1732, doi:10.3762/bjnano.6.176

• mechanisms are not activated by indentation. In the case of metallic glass, we conclude that the energy stored in the stressed volume during nanometer-scale indentation is insufficient to account for the interfacial energy of a shear band in the glassy matrix. Keywords: AFM indentation; dislocation

• the generation of shear bands in metallic glasses [4]. Dislocation nucleation and shear band generation are mechanisms that operate at the nanometer scale. In order to investigate the fundamental mechanisms contributing to the mechanical behavior of materials new advanced experimental techniques are

• account for energy release to the area of a shear band traversing the sample. More recently, it has been shown that despite the disappearance of shear bands and shear steps at sample surfaces upon the decrease of sample size one could still observe intermittence in stress–strain curves [11][12]. The

Influence of grain size and composition, topology and excess free volume on the deformation behavior of Cu–Zr nanoglasses

• Daniel Şopu and
• Karsten Albe

Beilstein J. Nanotechnol. 2015, 6, 537–545, doi:10.3762/bjnano.6.56

• annihilation spectroscopy [9], while molecular dynamics studies showed that glass–glass interfaces exhibit an excess free volume and a modified local order [10][11]. If plastically deformed, the soft glass in the interfaces promotes shear band nucleation similar to the effect of residual shear bands in pre

• multiple shear bands, in contrast to the BMG which exhibits localized deformation in one dominant shear band. In order to study how the deformation mechanism of NGs changes by varying the glassy grain size the local atomic shear strain was calculated for each of these NGs and BMG (Figure 2). Up to a strain

• of 8% in all three NGs, the shear transformation zones (STZs) are mostly activated in the soft interface regions. Although the shear band nucleation process is similar in all three NGs, the shear band propagation in case of the NG with the largest grain size strongly differs from to the other two NGs

Nanoglasses: a new kind of noncrystalline materials

• Herbert Gleiter

Beilstein J. Nanotechnol. 2013, 4, 517–533, doi:10.3762/bjnano.4.61

• stress seems to result from the lower nucleation barrier for shear transformation zones (STZ) at the nanoglass interfaces [53]. Since shear band propagation is driven by the local elastic energy, the local energy release is not sufficient to accelerate one of these local STZ so that it became a shear

• band. As a consequence, both nanoglasses deformed homogeneously (Figure 19). A comparable effect has already been reported for metallic glasses that were pre-deformed by cold rolling [48]. In fact, it may be described in a more quantitative way by the strain localization parameter proposed by Cheng et