A Concordant Shift Model for Flow in Bulk Metallic Glasses

doi:10.1007/s40195-016-0369-2

Abstract

Abstract:

The homogeneous plastic flow in bulk metallic glasses (BMGs) must be elucidated by an appropriate atomistic mechanism. It is proposed that a so-called concordant shifting model, based on rearrangements of five-atom subclusters, can describe the plastic strain behaviour of BMGs in a temperature range from room temperature to the supercooled liquid region. To confirm the effectiveness of the atomic concordant shifting model, a comparative investigation between the vacancy/atom model and the concordant shifting model is carried out based on the estimation of the strain rate deduced from two models. Our findings suggest that the atomic concordant shifting model rather than the vacancy/atom exchange model can well predict the large strain rate in the superplasticity of BMGs.

Key words: Bulk, metallic, glasses, Superplasticity, Vacancy/atom, exchange, model, Atomic, concordant, shifting, model, Strain, rate

Gang Wang, Zbigniew H. Stachurski. A Concordant Shift Model for Flow in Bulk Metallic Glasses[J]. Acta Metallurgica Sinica (English Letters), 2016, 29(2): 134-139.

Figures/Tables 4

Fig. 1 A view of a primitive random cluster comprising an inner sphere, A, and 7 outer sphere. A five-atom subcluster (coloured in blue) can deform into the α formation under tensile elongation, or into the β formation in compression as shown on the right

Fig. 2 Schematic variation of potential energy for the α-β transformation event, showing an activation barrier at some critical value of h/r, where h is the height of the five-atom subcluster and r is the sphere radius

Fig. 3 Variation of potential energy of the system with applied elongation, manifesting a sudden drop associated with α-β event

Table 1 Comparison of the two models of homogeneous flow

Model	Concentration,c	Diffusivity,D (m²/s)	Diffusion distance, λ(m)	Predicted strain rate (s^-1)
Vacancy/atom	0.02 (free volume)	10^-19	10^-4	1 × 10^-8
Concordant	0.2 (every fifth atom)	10^-19	10^-9	1 × 10^-3

References 32

[1]	C.A. Schuh, T.C. Hufnagel, U. Ramamurty, Acta Mater. 55,4067(2007)
[2]	Y. Kawamura, T. Nakamura, A. Inoue, Scr. Mater. 39, 301(1998)
[3]	W.J. Kim, D.S. Ma, H.G. Jeong, Scr. Mater. 39, 1067(2003)
[4]	J. Lu, G. Ravichandran, W.L. Johnson, Acta Mater. 51, 3429(2003)
[5]	B. Gun, K.J. Laws, M. Ferry, J. Non-Cryst. Solids 352, 3896 (2006)
[6]	J. Shen, G. Wang, J.F. Sun, Z.H. Stachurski, C. Yan, L. Ye, B.D.Zhou, Intermtallics 13, 79 (2005)
[7]	G. Wang, I. Jackson, J.D.J. Non-Cryst. Solids 354, 1575 (2008)
[8]	G. Wang, J. Shen, J.F. Sun, Y.J. Huang, J. Zou, Z.P. Lu, Z.H.Stachurski, B.D. Zhou, J. Non-Cryst. Solids 351, 209 (2005)
[9]	Y.H. Liu, G. Wang, R.J. Wang, D.Q. Zhao, M.X. Pan, W.H.Wang, Science 315, 1835 (2007)
[10]	R.C. Giffkins, Scr. Metall. 7, 27(1973)
[11]	J.W. Edington, K.N. Melton, C.P. Cutler, Prog. Mater Sci. 21, 61(1976)
[12]	T.G. Nieh, J. Wadsworth, O.D. Sherby, Superplasticity in Metals and Ceramics (Cambridge University Press, Cambridge, 1997),p. 240
[13]	V.A. Levashov, J.R. Morris, T. Egami, Phys. Rev. Lett. 106,115703(2011)
[14]	F. Spaepen, Acta Metall. 25, 407(1977)
[15]	H. Nakajima, T. Kojima, K. Nonaka, T. Zhang, A. Inoue, N.Nishiyama, L2.2.1(2001)
[16]	H. Eyring, J. Chem. Phys. 4, 283(1936)
[17]	C.Y. Lee, T.R. Welberry, Z.H. Stachurski, Acta Mater. 58, 615(2010)
[18]	J.D. Eshelby, Proc. R. Soc. A 241, 376 (1957)
[19]	A.R. Yavari, A. Le Moulec, A. Inoue, N. Nishiyama, N. Lupu,E. Matsubara, W.J. Botta, G. Vaughan, M. Di Michiel, A. Kvick,Acta Mater. 53, 1611(2005)
[20]	R. Ekambaram, P. Thamburaja, N. Nikabdullah, Mech. Mater.40, 487(2008)
[21]	M. Heggen, F. Spaepen, M. Feuerbacher, J. Appl. Phys. 97,033506(2005)
[22]	J.C. Ye, J. Lu, C.T. Liu, Q. Wang, Y. Yang, Nat. Mater. 9, 619(2010)
[23]	A.S. Argon, Acta Metall. 27, 47(1979)
[24]	P. Thamburaja, N. Nikabdullah, Scr. Mater. 65, 751(2011)
[25]	G. Wang, N. Mattern,Acta Mater. 60, 3074(2012)
[26]	K. Trachenko, V.V. Brazhkin, J. Phys.: Condens. Matter 21,425104 (2009)
[27]	W. Dmowski, T. Iwashita, C.P. Chuang, J. Almer, T. Egami,Phys. Rev. Lett. 105, 205502(2010)
[28]	Z.Y. Liu, G. Wang, K.C. Chan, J.L. Ren, X.L. Bian, Y.J. Huang,X.H. Xu, D.S. Zhang, Y.L. Gao, Q.J. Zhai, J. Appl. Phys. 114,033520(2013)
[29]	Z. Wang, B.A. Sun, H.Y. Bai, W.H. Wang, Nat. Commun. 5,5823(2014)
[30]	B.A. Sun, Z.Y. Liu, Y. Yang, C.T. Liu, Appl. Phys. Lett. 105,091904(2014)
[31]	Q. Wang, S.T. Zhang, Y. Yang, Y.D. Dong, C.T. Liu, J. Lu, Nat.Commun. 6, 7876(2015)
[32]	B.A. Sun, W.H. Wang, Prog. Mater Sci. 74, 211(2015 )G. Wang, Z. H. Stachurski: Acta Metall. Sin.(Engl. Lett.), 2016, 29(2), 134-139 139