© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Phys. Status Solidi RRL 3, No. 2 – 3, 46– 48 (2009) / DOI 10.1002/pssr.200802242 www.pss-rapid.com pss Deformation-induced microstructural heterogeneity in monolithic Zr 44 Ti 11 Cu 9.8 Ni 10.2 Be 25 bulk metallic glass Min Ha Lee *, 1, 2 , Jin Kyu Lee 2 , Kyung Tae Kim 1 , Jürgen Thomas 1 , Jayanta Das 1 , Uta Kühn 1 , and Jürgen Eckert 1, 3 1 IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, 01171 Dresden, Germany 2 Advanced Materials Division, Korea Institute of Industrial Technology, Incheon 406-840, Korea 3 TU Dresden, Institute of Materials Science, 01062 Dresden, Germany Received 31 October 2008, revised 7 December 2008, accepted 15 December 2008 Published online 19 December 2008 PACS 61.43.Fs, 64.70.pe, 68.37.Lp, 68.37.Ma, 81.40.Lm * Correspondence author: e-mail mhlee1@kitech.re.kr © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Metallic glasses, especially bulk metallic glasses (BMGs) are interesting for basic science as well as for po- tential applications because of their exceptional mechani- cal properties, including high strength, large elastic limit and low Young’s modulus [1–4]. However, due to the ab- sence of well-defined atomic planes or slip systems, plastic flow occurs inhomogeneously and is localized into narrow shear bands resulting in catastrophic failure [1–4]. As a re- sult most BMGs show little macroscopic plasticity (< 1%) at room temperature. In order to increase the reliability of BMGs, the enhancement of plasticity is a crucial issue for their use as structural materials. There have been several reports on synthesizing “ductile” BMGs which show large macroscopic plasticity at room temperature by introducing inhomogeneities with different length scale [5–7]. Recently, an abnormally large plasticity of monolithic BMG at room temperature was observed for a specifically composition- ally tailored super-plastic Zr 64.13 Cu 15.75 Ni 10.12 Al 10 BMG [5]. The super-plasticity was supposed to be due to distinctive microstructural features, found in TEM investigations, that are notably composed of continuously distributed inho- mogeneities in contrast, i.e. with white contrast regions which are surrounded by dark contrast regions of microme- ter size. However, other researchers claimed that such microstructural inhomogeneities may be artifacts due to improper sample preparation. Therefore, exploiting micro- structural differences based on a comparative study be- tween the as-cast state and of samples subjected to severe deformation under the same preparation condition is help- ful to understand the origin of inhomogeneities in the glassy phase. In the current study, we report on strain-induced mi- crostructural inhomogeneities in a typical brittle Zr 44 Ti 11 Cu 9.8 Ni 10.2 Be 25 BMG (Vitreloy 1b) subjected to room temperature deformation, i.e. cold rolling [8–10]. In microstructurally isotropic and chemically homoge- neous BMGs plastic flow is inhomogeneous below the glass transition temperature T g , and tends to be localized within a small number of shear bands upon the onset of yielding [11, 12]. Figure 1 displays an SEM image of the surface of the Zr-based BMG after deformation showing shear bands on the deformed surface. The inset displays We present investigations on the development of micro- structural inhomogeneity introduced by simple room tem- perature deformation for a typical bulk metallic glass (Zr 44 Ti 11 Cu 9.8 Ni 10.2 Be 25 ). The experimental evidence (e.g., transmission electron microscopy, electron energy dispersive X-ray spectroscopy and density measurements) clearly sup- ports that an inhomogeneous glassy structure can be produced during deformation in the bulk metallic glass, that does not depend on a specific pinpointed chemical composition. The micrometer-sized structural inhomogeneity in the monolithic bulk metallic glass originates from deformation due to the in- troduction of a high concentration of free volume in the glassy phase without significant change in the local chemical composition.