Abstract
Structural instabilities of nanocrystalline and ultrafine-grained (UFG) materials have been recognized as a major challenge during cyclic loading, especially in the low cycle fatigue regime. Although a severe deterioration of the mechanical properties has been reported during cyclic deformation, quantification of the softening portion solely due to grain coarsening was not possible. It will be demonstrated that cyclic high pressure torsion (CHPT) is a versatile method to enable direct measurement of the impact of grain coarsening on cyclic softening, as failure of the sample is prevented. Here, CHPT experiments have been performed on 99.99% UFG nickel. Grain coarsening similar to conventional uniaxial fatigue experiments was observed and could be studied up to large cyclic accumulated macro strains of 50. The correlation of electron back scatter diffraction images with microhardness measurements facilitated quantification of the cyclic softening as a consequence of grain growth for the very first time. Further, structural investigations revealed distinctly enhanced grain coarsening within shear bands. Thus, the cyclic strain seems to be the most important parameter controlling mechanically driven boundary migration during cyclic loading at low homologous temperatures.
Similar content being viewed by others
References
H. Mughrabi, H.W. Höppel, and M. Kautz: Fatigue and microstructure of ultrafine-grained metals produced by severe plastic deformation. Scr. Mater. 51 (8), 807 (2004).
O. Renk, A. Hohenwarter, S. Wurster, and R. Pippan: Direct evidence for grain boundary motion as the dominant restoration mechanism in the steady-state regime of extremely cold-rolled copper. Acta Mater. 77 (100), 401 (2014).
T. Yu, N. Hansen, X. Huang, and A. Godfrey: Observation of a new mechanism balancing hardening and softening in metals. Mater. Res. Lett. 2 (3), 160–165 (2014).
O. Renk, P. Ghosh, and R. Pippan: Generation of extreme grain aspect ratios in severely deformed tantalum at elevated temperatures. Scr. Mater. 137, 60 (2017).
D.S. Gianola, S. van Petegem, M. Legros, S. Brandstetter, H. van Swygenhoven, and K.J. Hemker: Stress-assisted discontinuous grain growth and its effect on the deformation behavior of nanocrystalline aluminum thin films. Acta Mater. 54 (8), 2253 (2006).
D.S. Gianola, B.G. Mendis, X.M. Cheng, and K.J. Hemker: Grain-size stabilization by impurities and effect on stress-coupled grain growth in nanocrystalline Al thin films. Mater. Sci. Eng., A 483–484, 637 (2008).
T.J. Rupert, D.S. Gianola, Y. Gan, and K.J. Hemker: Experimental observations of stress-driven grain boundary migration. Science 326 (5960), 1686 (2009).
M. Legros, D.S. Gianola, and K.J. Hemker: In situ TEM observations of fast grain-boundary motion in stressed nanocrystalline aluminum films. Acta Mater. 56 (14), 3380 (2008).
M. Jin, A.M. Minor, E.A. Stach, and J.W. Morris: Direct observation of deformation-induced grain growth during the nanoindentation of ultrafine-grained Al at room temperature. Acta Mater. 52 (18), 5381 (2004).
F. Mompiou, M. Legros, A. Boé, M. Coulombier, J-P. Raskin, and T. Pardoen: Inter- and intragranular plasticity mechanisms in ultrafine-grained Al thin films: An in situ TEM study. Acta Mater. 61 (1), 205 (2013).
K. Zhang, J.R. Weertman, and J.A. Eastman: Rapid stress-driven grain coarsening in nanocrystalline Cu at ambient and cryogenic temperatures. Appl. Phys. Lett. 87 (6), 061921 (2005).
B. Yang, H. Vehoff, A. Hohenwarter, M. Hafok, and R. Pippan: Strain effects on the coarsening and softening of electrodeposited nanocrystalline Ni subjected to high pressure torsion. Scr. Mater. 58 (9), 790 (2008).
R. Pippan, S. Scheriau, A. Taylor, M. Hafok, A. Hohenwarter, and A. Bachmaier: Saturation of fragmentation during severe plastic deformation. Annu. Rev. Mater. Res. 40 (1), 319 (2010).
S. Agnew and J. Weertman: Cyclic softening of ultrafine grain copper. Mater. Sci. Eng., A 244 (2), 145 (1998).
L. Kunz, P. Lukáš, and M. Svoboda: Fatigue strength, microstructural stability and strain localization in ultrafine-grained copper. Mater. Sci. Eng., A 424 (1–2), 97 (2006).
D. Canadinca, T. Niendorf, and H.J. Maier: A comprehensive evaluation of parameters governing the cyclic stability of. Mater. Sci. Eng., A 528, 6345 (2011).
H.W. Höppel, Z.M. Zhou, H. Mughrabi, and R.Z. Valiev: Microstructural study of the parameters governing coarsening and cyclic softening in fatigued ultrafine-grained copper. Philos. Mag. A 82, 1781 (2002).
M.W. Kapp, T. Kremmer, C. Motz, B. Yang, and R. Pippan: Structural instabilities during cyclic loading of ultrafine-grained copper studied with micro bending experiments. Acta Mater. 125, 351 (2017).
H.W. Höppel, C. Xu, M. Kautz, N. Barta-Schreiber, T.G. Langdon, and H. Mughrabi: Cyclic deformation behaviour and possibilities for enhancing the fatigue properties of ultrafine-grained metals. In Nanomaterials by Severe Plastic Deformation, M. Zehetbauer and R.Z. Valiev, eds. (Wiley-VCH, Weinheim, Germany 2004); p. 677.
N.A. Mara, D. Bhattacharyya, J.P. Hirth, P. Dickerson, and A. Misra: Mechanism for shear banding in nanolayered composites. Appl. Phys. Lett. 97 (2), 021909 (2010).
S.J. Zheng, J. Wang, J.S. Carpenter, W.M. Mook, P.O. Dickerson, N.A. Mara, and I.J. Beyerlein: Plastic instability mechanisms in bimetallic nanolayered composites. Acta Mater. 79, 282 (2014).
M.W. Kapp, A. Hohenwarter, S. Wurster, B. Yang, and R. Pippan: Anisotropic deformation characteristics of an ultrafine- and nanolamellar pearlitic steel. Acta Mater. 106, 239 (2016).
D. Jia, K.T. Ramesh, and E. Ma: Effects of nanocrystalline and ultrafine grain sizes on constitutive behavior and shear bands in iron. Acta Mater. 51 (12), 3495 (2003).
S.R. Agnew, A.Y. Vinogradov, S. Hashimoto, and J.R. Weertman: Overview of fatigue performance of Cu processed by severe plastic deformation. J. Electron. Mater. 28 (9), 1038 (1999).
A. Vinogradov, Y. Kaneko, K. Kitagawa, S. Hashimoto, and R.Z. Valiev: On the cyclic response of ultrafine-grained copper. Mater. Sci. Forum 269–272, 987 (1998).
S.D. Wu, Z.G. Wang, C.B. Jiang, and G.Y. Li: Scanning electron microscopy-electron channelling contrast investigation of recrystallization during cyclic deformation of ultrafine grained copper processed by equal channel angular pressing. Philos. Mag. Lett. 82 (10), 559 (2002).
S.D. Wu, Z.G. Wang, C.B. Jiang, G.Y. Li, I.V. Alexandrov, and R.Z. Valiev: Shear bands in cyclically deformed ultrafine grained copper processed by ECAP. Mater. Sci. Eng., A 387–389, 560 (2004).
H. Mughrabi and H.W. Höppel: Cyclic deformation and fatigue properties of very fine-grained metals and alloys. Int. J. Fatigue 32 (9), 1413 (2010).
M. Wong, W. Kao, J. Lui, C. Chang, and P. Kao: Cyclic deformation of ultrafine-grained aluminum. Acta Mater. 55 (2), 715 (2007).
F. Wetscher and R. Pippan: Cyclic high-pressure torsion of nickel and Armco iron. Philos. Mag. 86 (36), 5867 (2006).
E. Schafler and R. Pippan: Effect of thermal treatment on microstructure in high pressure torsion (HPT) deformed nickel. Mater. Sci. Eng., A 387–389, 799 (2004).
P. Ghosh, O. Renk, and R. Pippan: Microtexture analysis of restoration mechanisms during high pressure torsion of pure nickel. Mater. Sci. Eng., A 684, 101 (2017).
L. Toth, P. Gilormini, and J. Jonas: Effect of rate sensitivity on the stability of torsion textures. Acta Metall. Mater. 36 (12), 3077 (1988).
L. Kunz, P. Lukáš, L. Pantelejev, and O. Man: Stability of ultrafine-grained structure of copper under fatigue loading. Procedia Eng. 10, 201 (2011).
B.L. Boyce and H.A. Padilla: Anomalous fatigue behavior and fatigue-induced grain growth in nanocrystalline nickel alloys. Metall. Mater. Trans. A 42 (7), 1793 (2011).
R.A. Meirom, D.H. Alsem, A.L. Romasco, T. Clark, R.G. Polcawich, J.S. Pulskamp, M. Dubey, R.O. Ritchie, and C.L. Muhlstein: Fatigue-induced grain coarsening in nanocrystalline platinum films. Acta Mater. 59 (3), 1141 (2011).
O. Glushko and M.J. Cordill: The driving force governing room temperature grain coarsening in thin gold films. Scr. Mater. 130, 42 (2017).
S. Brandstetter, K. Zhang, A. Escuadro, J.R. Weertman, and H. van Swygenhoven: Grain coarsening during compression of bulk nanocrystalline nickel and copper. Scr. Mater. 58 (1), 61 (2008).
T.H. Fang, W.L. Li, N.R. Tao, and K. Lu: Revealing extraordinary intrinsic tensile plasticity in gradient nano-grained copper. Science 331 (6024), 1587 (2011).
F. Mompiou and M. Legros: Quantitative grain growth and rotation probed by in situ TEM straining and orientation mapping in small grained Al thin films. Scr. Mater. 99, 5 (2015).
J.E. Carsley, A. Fisher, W.W. Milligan, and E.C. Aifantis: Mechanical behavior of a bulk nanostructured iron alloy. Metall. Mater. Trans. A 29 (9), 2261 (1998).
B.J. Duggan, M. Hatherly, W.B. Hutchinson, and P.T. Wakefield: Deformation structures and textures in cold-rolled 70:30 brass. Met. Sci. 12 (8), 343 (2013).
F.J. Humphreys and M. Hatherly: Recrystallization and Related Annealing Phenomena, 2nd ed. (Elsevier, Oxford, U.K., 2004).
J.M. Finney and C. Laird: Strain localization in cyclic deformation of copper single crystals. Philos. Mag. 31 (2), 339 (1975).
A. Rajabzadeh, M. Legros, N. Combe, F. Mompiou, and D.A. Molodov: Evidence of grain boundary dislocation step motion associated to shear-coupled grain boundary migration. Philos. Mag. 93 (10–12), 1299 (2013).
ACKNOWLEDGMENT
Financial support by the FWF Austrian Science Fund within project number P24429-N20 is gratefully acknowledged.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Kapp, M.W., Renk, O., Leitner, T. et al. Cyclically induced grain growth within shear bands investigated in UFG Ni by cyclic high pressure torsion. Journal of Materials Research 32, 4317–4326 (2017). https://doi.org/10.1557/jmr.2017.273
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1557/jmr.2017.273