Size-dependent flowing characteristics of a Zr-based bulk metallic glass in the supercooled liquid region

Li, N.; Li, D.J.; Wang, Xinyun; Liu, L.

doi:10.1016/j.jallcom.2012.01.136

Cited by 12 publications

(3 citation statements)

References 27 publications

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“…It implies that the apparent viscosity increases with the sample size decreasing in the millimeter scale. A similar phenomenon was reported in other BMGs and nano-scale1821. In Figure 1b, it is interesting that the stress–strain curve of the smallest sample (Ø0.6 mm) exhibits a distinct stress overshoot under the condition of 704 K and 0.005 s −1 .…”

Section: Resultssupporting

confidence: 86%

“…However, Zheng17 indicated that the flow stress of Mg-based BMG increases with sample diameter decreasing in millimeter scales. In the SCLR, Li18 reported that the compressive stress of Zr 65 Cu 17.5 Ni 10 Al 7.5 BMG increases with decreasing sample size at various strain rates. Wang19 also indicated that the smaller the specimen, the higher the flow stress will be, namely ‘smaller is harder'.…”

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confidence: 99%

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A size-dependent constitutive model of bulk metallic glasses in the supercooled liquid region

Yao

Deng

Zhang

et al. 2015

Sci Rep

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Size effect is of great importance in micro forming processes. In this paper, micro cylinder compression was conducted to investigate the deformation behavior of bulk metallic glasses (BMGs) in supercooled liquid region with different deformation variables including sample size, temperature and strain rate. It was found that the elastic and plastic behaviors of BMGs have a strong dependence on the sample size. The free volume and defect concentration were introduced to explain the size effect. In order to demonstrate the influence of deformation variables on steady stress, elastic modulus and overshoot phenomenon, four size-dependent factors were proposed to construct a size-dependent constitutive model based on the Maxwell-pulse type model previously presented by the authors according to viscosity theory and free volume model. The proposed constitutive model was then adopted in finite element method simulations, and validated by comparing the micro cylinder compression and micro double cup extrusion experimental data with the numerical results. Furthermore, the model provides a new approach to understanding the size-dependent plastic deformation behavior of BMGs.

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Section: Resultssupporting

confidence: 86%

mentioning

confidence: 99%

A size-dependent constitutive model of bulk metallic glasses in the supercooled liquid region

Yao

Deng

Zhang

et al. 2015

Sci Rep

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show abstract

“…However, the poor manufacturing ability origins from the high strength and ambient-temperature brittleness has been the Achilles' heel to structural applications of MGs [6,7]. In the past decade, efforts have been devoted to fabricate MGs components with precise and versatile geometries, though the main techniques mainly focus on mold casting [8], thermoplastic forming [5,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] and additive manufacturing [27][28][29]. By comparing with mold casting and additive manufacturing, the superiorities of thermoplastic forming is worth noting, for example, (1) the existence of supercooled liquid regime (SCLR) between the glass-transition temperature (Tg) and the crystallization temperature (Tx) allows thermoplastic forming (TPF) of MGs under low-forming strength [6], which breaks through the limitations of poor processability of MGs at ambient temperature; (2) net-shaping of precise and versatile geometries with minimum size of atom-scale could be realized, that were previously unachievable with any conventional crystalline metals; (3) the absence of phase transition of MGs during solidification endows them small solidification shrinkage (1/20 of typical casting alloys) [30], which is beneficial to the net-shaping with high precision and (4)as mentioned earlier, MGs maintain more excellent mechanical properties than crystalline metals.…”

Section: Introductionmentioning

confidence: 99%

Thermoplastic Forming of Metallic Glasses

Li¹,

Ma²

2018

Metallic Glasses - Properties and Processing

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Metallic glasses (MGs) are an unusual class of materials that possess an amorphous atomic-level structure and display a plethora of desirable mechanical, chemical and physical properties, which makes them one of the most promising engineering materials. However, the poor processability of metallic glasses greatly hindered their engineering applications. Though some techniques have been developed to fabricate metallic glass components, the unique superplasticity of supercooled liquid metallic glasses attracts enduring attentions, which allows thermoplastic forming of metallic glasses on length scales ranging from atomic-size to centimeter and especially offers an alluring prospect in the field of microfabrication. While some pivotal aspects during thermoplastic forming of metallic glasses should be addressed, for example, the evaluation of thermoplastic formability and its relationship with material flowing characteristic, the required thermoplastic forming techniques for processing MG components with high quality and the potential applications of these thermoplastic formed textures are compressively reviewed in this chapter.

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Synthesis and self‐assembled mechanism of CuO peony‐flowers by a composite hydroxide‐mediated approach at low temperature

Liu

Jin

Hou

et al. 2014

Crystal Research and Technology

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A composite‐hydroxide mediated (CHM) method was utilized for the synthesis of CuO peony‐flower nanostructures under temperatures ranging between 25 and 160 °C. The CHM mechanism was confirmed through X‐ray Powder Diffraction (XRD) and a Thermo‐Gravimetric Differential Scanning Calorimeter (TG‐DSC). Cu(NO3)2 was shown to transform into Cu(OH)2 in the mixed alkalis (NaOH/KOH); the reaction was facilitated by the solvent properties of the mixed alkalis. Cu(OH)2 subsequently consumed H2O in the adsorption of the mixed alkalis at 25∼65 °C. At higher reaction temperatures (>65 °C), the Cu(OH)2 was seen to decompose at an accelerated rate. Therefore, crystalline CuO could be obtained not only above 65 °C but also at 25 °C. The crystal morphology and structure of CuO were examined through Filed Emission Scanning Electron Microscopy (FE‐SEM) and Transmission Electron Microscopy (TEM). It was determined that the CuO peony‐flower had a polycrystalline structure composed of single crystalline CuO petals. Using the Selected Area Electron Diffraction (SAED) results, the rings were indexed as (002), (111), (112), (202) and (−113), which was in agreement with the XRD results. With increasing temperature, the CuO flower petals self‐assembled through random aggregation and gathered CuO nanorod parts, which led to incomplete CuO flower petals through orientated aggregation. Prolonged reaction time led to the growth of CuO flower petals in the direction of [001]. An ideal CuO flower structure was observed through TEM observation.

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Size-dependent flowing characteristics of a Zr-based bulk metallic glass in the supercooled liquid region

Cited by 12 publications

References 27 publications

A size-dependent constitutive model of bulk metallic glasses in the supercooled liquid region

A size-dependent constitutive model of bulk metallic glasses in the supercooled liquid region

Thermoplastic Forming of Metallic Glasses

Synthesis and self‐assembled mechanism of CuO peony‐flowers by a composite hydroxide‐mediated approach at low temperature

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