Orientation imaging microscopy of ultrafine-grained nickel

Zhilyaev, Alexander P.; Kim, B.-K.; Nurislamova, G. V.; Baró, Maria Dolores; Szpunar, Jerzy A.; Langdon, Terence G.

doi:10.1016/s1359-6462(02)00018-0

Cited by 238 publications

(151 citation statements)

References 21 publications

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“…Several different methods of SPD processing are now available but the primary methods are equal-channel angular pressing (ECAP) [4], high-pressure torsion (HPT) [5], accumulative roll bonding (ARB) [6] and multi-directional forging [7]. To date, most attention has focused on ECAP and HPT and it is now well established that processing by HPT produces materials having smaller grain sizes than ECAP [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Using an Al–Cu binary alloy to compare processing by multi-axial compression and high-pressure torsion

Zhang

et al. 2013

Materials Science and Engineering: A

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a b s t r a c tAn Al-4% Cu alloy was selected as a model material in order to compare two different procedures for imposing severe plastic deformation: multi-axial compression (MAC) and high-pressure torsion (HPT). In MAC a compressive strain is applied to prismatic samples in a sequential order along three orthogonal directions and the process is repeated to large numbers of passes in order to attain high strains. In HPT a thin disk is held between anvils and subjected to a high applied pressure and concurrent torsional straining. The results show that HPT is the optimum procedure for producing a homogeneous ultrafinegrained material. Specifically, HPT is preferable because it produces materials having a larger degree of homogeneity and the equilibrium grain sizes are smaller and the Vickers microhardness values are higher than when processing by MAC.

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Section: Introductionmentioning

confidence: 99%

Using an Al–Cu binary alloy to compare processing by multi-axial compression and high-pressure torsion

Zhang

et al. 2013

Materials Science and Engineering: A

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“…For such a transformation to take place, a large accumulation of crystal lattice defects is required, which is not achievable by the conventional methods of forming. In this context, special deformation methods have been developed, including Equal Channel Angular Pressing (Valiev and Langdon, 2006), High Pressure Torsion (Zhilayaev et al, 2002), Cyclic Extrusion Compression (Richert et al, 1999) and Multi Axial Forging (Cherukuri et al, 2005). More recently, Hydrostatic Extrusion, HE, has also been used to this end (Lewandowska et al, 2007;Lewandowska and Kurzydlowski, 2008).…”

Section: Application To Nanomaterials Nano-polycrystalline Materialsmentioning

confidence: 99%

Stereology of Nano-Materials

Wejrzanowski¹,

Lewandowska²,

Kurzydłowski³

2011

Image Anal Stereol

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Nano-structured materials attract a growing attention due to their superior mechanical and physical properties. Such properties are inherently related to the unique structure which is controlled at the nano-scale. In the early stage of their development, the structural characterization of nano-materials was limited to the average grain/particle size. However, nano-grains/particles form stochastic populations with diverse size and shape. The recent experimental and theoretical results show that in addition to the average size, size diversity of grains/particles has a significant effect on the properties of nano-materials. This rationalizes more advanced description of the structures of nano-materials. Advanced microscopic methods are now available to image microstructure of nano-materials, e.g., HRSTEM and AFM. The ultra-high resolution images can be efficiently processed to obtain quantitative description of the nano-grains/particles. Examples are shown how such a description can be used for optimizing the microstructures of modern engineering nano-materials.

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“…The values of R C and ρ may be determined from X-ray experiments and the value for A * can be taken as the weighted sum for the screw and edge dislocations: Usually, the value of γ represents all types of grain boundaries in the material. However, earlier experiments showed that the grain boundary misorientation distribution in UFG nickel subjected to SPD processing is bimodal [42] and the energy of the low-angle boundaries depends strongly on the misorientation angle. Strictly, it is necessary also to consider not the fraction of any particular type of boundary but rather their relative area (or length in a two-dimensional model).…”

Section: Discussionmentioning

confidence: 92%

“…The experimental data were collected using a Philips XL-30 FEG scanning electron microscope (SEM) with a TSL orientation imaging system [42,48]. The mean grain size was estimated for each condition using a JEOL transmission electron microscope.…”

Section: Experimental Materials and Proceduresmentioning

confidence: 99%

“…However, both of these parameters play a significant role in determining the bulk properties of the materials [27,28]. Some information has become available recently on the grain boundary misorientation distributions after ECAP of pure Al and Al alloys [29][30][31][32][33][34][35][36][37][38][39], ECAP of pure Cu [38,40,41], ECAP and HPT of pure nickel [5,42] and ECAP of pure Zr [43]. Although the results on pure Ni are fairly limited [42], the experimental data suggest that HPT produces a microstructure with a higher fraction of high-angle grain boundaries than ECAP.…”

Section: Introductionmentioning

confidence: 99%

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Microstructural Characteristics of Ultrafine-Grained Nickel

Zhilyaev¹

NATO Science Series

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A detailed investigation was conducted to evaluate the microstructural characteristics in samples of pure nickel processed using three different procedures of severe plastic deformation (SPD): equal-channel angular pressing (ECAP), high-pressure torsion (HPT) and a combination of ECAP and HPT. Several different experimental techniques were employed to measure the grain size distributions, the textures, the distributions of the misorientation angles and the boundary surface energies in the as-processed materials. It is shown that a combination of ECAP and HPT leads both to a greater refinement in the microstructure and to a smaller fraction of boundaries having low angles of misorientation. The estimated boundary surface energies were higher than anticipated from data for coarse-grained materials and the difference is attributed to the non-equilibrium character of many of the interfaces after SPD processing.

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Orientation imaging microscopy of ultrafine-grained nickel

Cited by 238 publications

References 21 publications

Using an Al–Cu binary alloy to compare processing by multi-axial compression and high-pressure torsion

Using an Al–Cu binary alloy to compare processing by multi-axial compression and high-pressure torsion

Stereology of Nano-Materials

Microstructural Characteristics of Ultrafine-Grained Nickel

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