Homogeneity of the superplastic Zr 64.13 Cu 15.75 Ni 10.12 Al 10 bulk metallic glass
- PDF / 801,989 Bytes
- 5 Pages / 584.957 x 782.986 pts Page_size
- 26 Downloads / 235 Views
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 Jianga) 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 Zr64.13Cu15.75Ni10.12Al10 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 properties, such as high strength, high hardness, large elastic limit, and high corrosion resistance, making them potential materials for structural applications.1,2 It is unfortunate 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 Zr64.13Cu15.75Ni10.12Al10 BMG synthesized through the appropriate selection of composition 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) a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2009.0395
3116
http://journals.cambridge.org
J. Mater. Res., Vol. 24, No. 10, Oct 2009 Downloaded: 18 Mar 2015
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 sample? 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 machi
Data Loading...
