Homogeneity of the Zr 64.13 Cu 15.75 Ni 10.12 Al 10 bulk metallic glass Lian-Yi Chen, Yue-Wu Zeng, and Qing-Ping Cao International Center for New-Structured Materials, Zhejiang University and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People’s Republic of China Byung-Joo Park, Yi-Meng Chen, and Kazuhiro Hono National Institute for Materials Science, Tsukuba 305-0047, Japan Ulla Vainio HASYLAB at DESY, Hamburg D-22607, Germany Zao-Li Zhang and Ute Kaiser Electron Microscopy Group of Materials Science, Ulm University, Ulm D-89069, Germany Xiao-Dong Wang and Jian-Zhong Jiang a) International Center for New-Structured Materials, Zhejiang University and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People’s Republic of China (Received 16 December 2008; accepted 20 March 2009) A recent report on the “room temperature superplasticity” in the Zr 64.13 Cu 15.75 Ni 10.12 Al 10 bulk metallic glass [Y.H. Liu et al., Science 315, 1385 (2007)] was ascribed to the distinctive micrometer-sized structural heterogeneity. To verify the microstructure in this alloy, transmission electron microscopy (TEM) and anomalous small-angle x-ray scattering experiments were conducted. The results show that no micrometer-sized or nanometer-sized structural heterogeneities can be found. The micrometer-sized dark and bright regions that were previously reported as the reason for the plasticity are artifacts caused by TEM specimen preparation, rather than the intrinsic structure feature of this alloy. This finding is important for further studying the unique properties of this alloy. I. INTRODUCTION Bulk metallic glasses (BMGs) exhibit unique proper- ties, such as high strength, high hardness, large elastic limit, and high corrosion resistance, making them poten- tial materials for structural applications. 1,2 It is unfortu- nate that the limited room temperature plasticity restricts the widespread application of BMGs as engineering materials. 3 More recently, great endeavors have been made to improve the plasticity of BMGs. 4–23 Liu et al. 15 reported a large true plastic strain of more than 160% at room temperature in Zr 64.13 Cu 15.75 Ni 10.12 Al 10 BMG synthesized through the appropriate selection of compo- sition and claimed the achievement of superplasticity at room temperature. They attributed the extraordinary plasticity to micrometer-sized structural heterogeneity (i.e., mixture of micrometer-sized high density and low density or hard and soft regions with undetectable composition difference), which was mainly detected from the micrometer-sized feature (i.e., bright and dark regions) in the transmission electron microscopy (TEM) image. 15 However, what the “soft” and “hard” regions mean is not clear and a question arises: whether or not such a unique structural feature is intrinsic for the sam- ple? The answer to this question is the key point for further understanding the unique properties of this alloy. On the other hand, the plastic strain was observed under the stress constraint condition with the cross-head of a compression testing machine as recently reported by Mondal et al. 24,25 In this work, TEM and anomalous small-angle x-ray scattering (ASAXS) experiments were carried out to examine the microstructural feature of the alloy to discuss the proposed mechanism of the macro- scopically large plastic deformation at room tempera- ture. The results show that the micrometer-sized feature in the TEM image does not correspond to the intrinsic structural heterogeneity of this alloy. II. EXPERIMENTAL Zr 64.13 Cu 15.75 Ni 10.12 Al 10 alloy ingots were prepared by arc melting the mixtures of pure Zr, Cu, Ni, and Al elements in a Ti-gettered high-purity argon atmosphere. Alloy strips with thickness of 1 mm and ribbons with thickness of 40 mm were prepared by copper mold suc- tion casting and melt-spinning, respectively. The strip a) Address all correspondence to this author. e-mail: jiangjz@zju.edu.cn DOI: 10.1557/JMR.2009.0395 J. Mater. Res., Vol. 24, No. 10, Oct 2009 © 2009 Materials Research Society 3116