GRAIN REFINEMENT AND DEFORMATION MECHANISMS IN HETEROGENEOUS ULTRAFINE-GRAINED MATERIALS PROCESSED BY ACCUMULATIVE ROLL BONDING

Göken M, Höppel HW, Hausöl T, Bach J, Maier V, Schmidt C, Amberger D (2012)


Publication Status: Published

Publication Type: Conference contribution

Publication year: 2012

Pages Range: 31-48

Abstract

Grain refinement by severe plastic deformation is nowadays intensively used to process pure metals and alloys. These ultrafine-grained and homogeneous materials show already a great potential concerning their mechanical properties. Recently, heterogeneous ultrafine-grained materials consisting of different metals or different alloys became also very attractive. A very promising production process for such multicomponent materials is accumulative roll bonding (ARB) which allows producing laminates with finely distributed micrometer-sized layers. Interesting heterogeneous materials can also be produced by particle incorporation in the ARB process. Hard ceramic particles lead to additional grain refinement of the surrounding metal matrix by flow around the spherical particles. Similar extra grain refinement processes occur also at the interfaces in heterogeneous laminates. Although the deformation mechanisms in such UFG materials have been investigated quite intensively, a generally accepted view is still missing. Especially the question if grain boundary sliding or thermally activated dislocation processes are the dominant deformation mechanism has to be clearly answered. It is generally accepted that the strain rate sensitivity of nanomaterials is significantly enhanced compared to coarse grained materials, which probably is the dominant contribution to the often reported enhanced ductility. In the literature some indications can be found that also grain boundary sliding occurs under specific conditions and is sometimes considered as the dominant deformation mechanism in nanomaterials. Here, different arguments based on macroscopic deformation experiments such as strain rate jump tests and fatigue tests are discussed. The results show that thermally activated dislocation processes at the grain boundaries are the dominant deformation mechanisms in UFG materials. In addition nanoindentation experiments and focused ion beam investigations indicate that grain boundary sliding occurs only at free surfaces but not in the bulk volume of ultrafine-grained materials. This leads to the suggestion that thermally activated deformation processes at grain boundaries are dominant in ultrafine-grained materials with grain size of some hundred nanometers.

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How to cite

APA:

Göken, M., Höppel, H.W., Hausöl, T., Bach, J., Maier, V., Schmidt, C., & Amberger, D. (2012). GRAIN REFINEMENT AND DEFORMATION MECHANISMS IN HETEROGENEOUS ULTRAFINE-GRAINED MATERIALS PROCESSED BY ACCUMULATIVE ROLL BONDING. (pp. 31-48).

MLA:

Göken, Mathias, et al. "GRAIN REFINEMENT AND DEFORMATION MECHANISMS IN HETEROGENEOUS ULTRAFINE-GRAINED MATERIALS PROCESSED BY ACCUMULATIVE ROLL BONDING." 2012. 31-48.

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