Texture transition due to stacking fault energy 2015-12-15 POSTECH Department of Materials Science and Engineering Jaimyun Jung

Texture transition in fcc metals Result of deformation (slip) related grain rotation Difference in texture may occur for materials with same crystal structure Different textures lead to different formability, strength, and fracture toughness (a),(c) {1 1 1}, (b),(d) {2 0 0} after 96% reduction Hu et al., 1952 Transition Rolling: Copper to brass-type transition Copper-type (Copper, S, and Bs-orientation; beta-fiber) vs brass-type (Goss and Bs-orientation; alpha-fiber) Extrusion/drawing: <111>-fiber to <100>-fiber transition

Result of the transition Texture transition Cause of transition The cause of this transition is now generally accepted as due to cross-slip events (Leffers et al., 2009) The lack of cross-slip in certain fcc alloy types nurtures the formation of twins and shear bands Result of the transition Non-cube recrystallization texture after rolling Reduced formability after rolling Reduced strength after extrusion/drawing

Stacking fault energy calculation (0K) Method Calculate stacking fault energies Compare against observed texture transition Stacking fault energy calculation (0K) Construct perfect lattice with y-direction parallel to <111> 1500 atoms for single elements 3000 atoms for alloys Relaxation at 0K Either remove a center layer or displace it Relaxation at 0K (free surface along <111> direction) For first method, {𝐸 𝑓 −( 𝐸 0 − 𝐸 𝑟𝑒𝑚𝑜𝑣𝑒𝑑 )}/(𝑆𝑡𝑎𝑐𝑘𝑖𝑛𝑔 𝑓𝑎𝑢𝑙𝑡 𝑎𝑟𝑒𝑎) For second, { 𝐸 𝑓 − 𝐸 0 }/(𝑆𝑡𝑎𝑐𝑘𝑖𝑛𝑔 𝑓𝑎𝑢𝑙𝑡 𝑎𝑟𝑒𝑎) Single element: Ni Ag Cu Al Pd Pt Au Binary: Ni-W Ni-Cu Ni-Al Ni-V For binary alloys, 2~3 specimens with random solute mixture are used to alleviate the effect of solute concentration on the stacking fault For each alloy, the solute concentration is ensured to fall within the range of single phase or mostly single phase fcc

Calculated stacking fault energies Solute frac. SFE (𝐦𝐉/ 𝐦 𝟐 ) Ref.[2] Ni-W 125 250 0.05 71 65 0.07 54 55 0.1 45 50 Ref.[3] Ni-Cu 225 0.25 101 100 0.5 84 Cu-Ni 44 0.2 56 70 0.3 69 Ref.[4] Ni-Al 132 0.03 -- 109 119 118 Ni-V 116 68 127 145 Calculated Ref.[1] Ni 125 Ag 21 Cu 44 42 Al 141 Pd 100 Pt 110 Au 40 [1] B.J. Lee, J.H. Shim, M.I. Baskes, Phys. Rev. B (2003) 68 [2] T.J. Rupert, J.C. Trenkle, C.A. Schuh, Acta. Mater. (2011) 59 [3] B. Somerday, P. Sofronis, R.H. Jones, Effects of hydrogen on materials: proceedings of 2008 interational hydrogen conference (2008) [4] S. Shang, H. Fang, Y. Wang, Y. Du, J Phys.: Condens. Matter(2012) 24

Published results on texture Single element experimental results: Ni, no transition up to 80% (Park, 1996) Ag, always Brass-type (Smallman, 1964) Cu, no transition up to 80%, prominent Brass at 97% (Hu, 1974) Al, no transition up to 95% (Lee, 2014) Au, no transition up to 95% (Smallman, 1964) Ni-Al experimental results: Ni-18at%Al no transition up to 95%, two phase (Li, 2008) Ni-V experimental results: Ni-10wt%V no transition up to 95% (Watanabe, 2000) Ni-11at%V no transition (Petrisor , 2002) Cu-Ni experimental results: Cu-10at%Ni no transition up to 95%(Sarma, 2007) Cu-35at%Ni no transition up to 95% (Sarma, 2007) Cu-45at%Ni no transition up to 99% (Tian, 2015) Ni-W experimental results: Ni-5at%W no transition at 97% (Bhattacharjee, 2009) Ni-9at%W transition at 95% (Sarma, 2004) Single element: Ni, Ag, Cu, Al, Pd, Pt, Au Binary alloy: Ni-Al Ni-V Ni-Cu Ni-W

Results Red: No transition observed Blue: Transition observed Black: No experimental data

Conclusion Transition criteria From experimental evidence, only Ag and Ni-10at%W exhibit brass-type texture after <50% and 95% reduction ratios, respectively. The above mentioned results, coupled with MD results, indicates 45 mJ/ m 2 as threshold SFE for transition at 95% and 21 mJ/ m 2 for transition at <50%. Cu and Au fall within the threshold SFE for transition at 95%, which is not true More low SFE fcc elements/alloys should be investigated to provide a better criteria (Cu-Al, Ni-Co, Cu-Zn)

References [1] B.J. Lee, J.H. Shim, M.I. Baskes. Phys. Rev. B (2003) 68. [2] T.J. Rupert, J.C. Trenkle. C.A. Schuh, Acta. Mater. (2011) 59. [3] B. Somerday, P. Sofronis, R.H. Jones, Effects of hydrogen on materials: proceedings of 2008 interational hydrogen conference (2008). [4] S. Shang, H. Fang, Y. Wang, Y. Du. J Phys.: Condens. Matter (2012) 24. [5] Y.B. Park, D. Raabe, T.H. Yim. Metals and Mater. (1996) 2. [6] R. Smallman, I. Dillamore, P. Dobson. J. de Phys. (1966) 27. [7] R. Smallman, D. Green. Acta. Metall. (1964) 12. [8] H. Hu. Texture of metals (1974). [9] V.S. Sarma, J. Eickemeyer, C. Mickel, L. Schultz, B. Holzapfel. Mater. Sci. Eng. A (2004) 380. [10] H. Tian, H. Suo, Y. Liang, Y. Zhao, J.-C. Grivel. Mater. Lett. (2015) 141. [11] V.S. Sarma, J. Eickemeyer, L. Schultz, B. Holzapfel. J. Mater. Sci. (2007) 42. [12] D. Li, K. Kishida, M. Demuar, T. Hirano. Intermetallics (2008) 16. [13] T. Watanabe, T. Maeda, K. Matsumoto, N. Uno, M. Ikeda, I. Hirabayashi. Advances in Superconductivity XII (2000). [14] T. Petrisor, V. Boffa, G. Celentano, L. Ciontea, F. Fabbri, V. Galluzzi, U. Gambardella, A. Mancini, A. Rufolonoi, E. Varesi. Physica C (2002) 377. [15] T. Leffers, R.K. Ray. Prog. Mater. Sci. (2009) 54. [16] P.P. Bhattacharjee, R.K. Ray, N. Tsuji. Acta Mater. (2009) 57.