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SINCE the early beginnings of high-pressure torsion (HPT) in the last century,[1] it has become one of the leading deformation techniques in the field of severe plastic deformation (SPD).[2,3] This popularity has some simple reasons, with the most important being that HPT allows the highest hydrostatic pressures among all SPD techniques, while at the same time, the specimen shape is not altered during deformation. Due to these characteristics, crack initiation is widely impeded and metallic samples are nowadays deformable to the highest ever reported degrees of deformation. From the experimental view, HPT also represents a very simple concept, which can be realized with relatively little technical and financial effort. Significant deformation parameters, such as testing temperature, imposed strain, and strain rate, are easily varied and well controlled so that in-depth studies on the microstructural response upon large deformation strains can be performed.[4] These advantages make the material selection for research studies quite versatile, ranging from soft pure metals to

A. HOHENWARTER is with the Department of Materials Physics, Montanuniversita¨t Leoben, Jahnstr. 12, 8700 Leoben, Austria. Contact email: [email protected] R. PIPPAN is with the Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstr. 12, 8700 Leoben, Austria. Manuscript submitted April 16, 2018. Article published online November 21, 2018 METALLURGICAL AND MATERIALS TRANSACTIONS A

hard and difficult to deform metals and alloys, to rather exotic materials for deformation experiments, such as ceramics[5,6] or semi-conductors.[7] Finally, this technique is not exclusively restricted to bulk precursor materials but is also applicable to powders.[8] As such, HPT can be used as a combined technique for powder consolidation of one or several different powders and subsequent deformation to create materials with outstanding mechanical and functional properties.[9,10] Even though HPT possesses several advantages, the sample size used for classical HPT is typically small, being 8 to 10 mm in diameter and 1 mm in thickness. Compared to other SPD processes, such as equal channel angular pressing or accumulative roll bonding, this drawback has a strong impact for the testing of the material. As an example, for tensile testing, an adequate strain measurement directly on the specimen can be difficult and the sample aspect ratios are often incomparable to standard samples. Moreover, many SPD processes as well as HPT possess elongated microstructures in specific inspection directions. Therefore, orientation-dependent properties, including various mechanical and physical ones, often are the subject of great research interest.[11] Finally, postdeformation studies, such as rolling experiments, on HPT-processed materials could provide valuable insights into the deformation behavior of SPD structures.[12] These fields of research require larger samples, especially with regard to the sample thickness. Along with the academic intere