Diffusion and surface alloying of gradient nanostructured metals

• Zhenbo Wang and
• Ke Lu

Beilstein J. Nanotechnol. 2017, 8, 547–560, doi:10.3762/bjnano.8.59

• layer of 2–10 nm in thickness has been formed along Al/Al GBs in UFG Al–Zn alloys after high pressure torsion at room temperature [47]. Dramatically enhanced GB diffusivities were observed in Cu–Bi and Fe–Si–Zn alloys with prewetted GBs [48][49]. Nevertheless, this notion might safely be excluded from

• transport of species and phase transitions might be significantly promoted during SPD, which usually triggers the states equivalent to higher temperatures [88]. For example, Straumal et al. [89] demonstrated that high pressure torsion at room temperature produced a solid solution with a certain steady-state

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

• grain boundaries are strongly affected by processing routes and conditions [53][54]. As for those bulk ultrafine-grained (UFG) materials produced by severe plastic deformation (SPD) (e.g., equal-channel angular pressing (ECAP) and high-pressure torsion (HPT) initiated by Valiev and Langdon [55][56

Effect of triple junctions on deformation twinning in a nanostructured Cu–Zn alloy: A statistical study using transmission Kikuchi diffraction

• Silu Liu,
• Xiaolong Ma,
• Lingzhen Li,
• Liwen Zhang,
• Patrick W. Trimby,
• Xiaozhou Liao,
• Yusheng Li,
• Yonghao Zhao and
• Yuntian Zhu

Beilstein J. Nanotechnol. 2016, 7, 1501–1506, doi:10.3762/bjnano.7.143

• /10 wt % Zn was first homogenized at 700 °C for 3 h, cooled down to room temperature, and then punched into 10 mm diameter disks for high pressure torsion (HPT) processing. The HPT processing was conducted at room temperature for ten revolutions with an imposed pressure of 1 GPa at a speed of 1.5 rpm

• -pressure torsion. It was found that in 83% of grains containing twins, at least one twin intersects with a triple junction. This suggests that triple junctions could have promoted the nucleation of deformation twins. It should be cautioned that this technique might be unable to detect extremely small

• , Australia 10.3762/bjnano.7.143 Abstract Scanning electron microscopy transmission Kikuchi diffraction is able to identify twins in nanocrystalline material, regardless of their crystallographic orientation. In this study, it was employed to characterize deformation twins in Cu/10 wt % Zn processed by high

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

• ], ball milling [14][15][16][24], cold rolling [12][25][26][27][28][29][30][31][32], high-pressure torsion straining [18][33], nanoindentation [34], and uniaxial compression [35]. The results of intense deformation have demonstrated nanocrystals with number densities of up to 1022 m−3 and average sizes of

The self-similarity theory of high pressure torsion

• Yan Beygelzimer,
• Roman Kulagin,
• Laszlo S. Toth and
• Yulia Ivanisenko

Beilstein J. Nanotechnol. 2016, 7, 1267–1277, doi:10.3762/bjnano.7.117

• , UMR 7239, Metz, F-57045, France 10.3762/bjnano.7.117 Abstract By analyzing the problem of high pressure torsion (HPT) in the rigid plastic formulation, we show that the power hardening law of plastically deformed materials leads to self-similarity of HPT, admitting a simple mathematical description

• -similarity. Outside these ranges, the plasticity problem still has to be solved for each value of β. The results obtained have important practical implications for the proper design and analysis of HPT experiments. Keywords: deformation mechanisms; high pressure torsion; nanocrystalline metals; self

• -similarity; severe plastic deformation; Introduction High pressure torsion (HPT) is a severe plastic deformation process, which is widely used for producing nanocrystalline metals and alloys [1][2][3]. The generally accepted theory of HPT is based on the assumptions of uniformity of simple shear deformation

Plasticity of nanocrystalline alloys with chemical order: on the strength and ductility of nanocrystalline Ni–Fe

• Jonathan Schäfer and
• Karsten Albe

Beilstein J. Nanotechnol. 2013, 4, 542–553, doi:10.3762/bjnano.4.63

• state was found after rolling at liquid nitrogen temperature to obtain a nanometer grain size [6]. In nanostructured Ni3Al processed by ball milling [7] or high pressure torsion [8], on the contrary, a complete loss of order is observed during preparation. Grain refinement by severe plastic deformation