Initiation and propagation of shear bands in Zr-based bulk metallic glass under quasi-static and dynamic shear loadings

Liu, L.F.; Dai, L.H.; Bai, Yilong; Wei, Bingchen

doi:10.1016/j.jnoncrysol.2005.07.030

Cited by 100 publications

(65 citation statements)

References 58 publications

(90 reference statements)

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“…Significant development of vein patterns confirms plastic flow before failure. In addition, localized melting and protruded viscous flow (Figure 4(c)) along the fracture surface are observed, indicating a significant rise in temperature during final fracture [22,23]. However, the deformation behaviors observed for the x=3, 4 alloys are very different from those with x=1, 2.…”

Section: Resultsmentioning

confidence: 98%

Effect of Sn addition on the glass-forming ability and mechanical properties of Ni-Nb-Zr bulk metallic glasses

Zhang

Wang

et al. 2011

Chin. Sci. Bull.

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The effect of tin (Sn) addition on the glass forming ability (GFA) and mechanical properties of the Ni-Nb-Zr ternary alloy system has been studied. The addition of Sn improves the GFA; Ni 61 Nb 35.5-x Zr 3.5 Sn x (in at.%) alloys with x=1 can be cast into amorphous samples at least 3 mm in diameter using a copper mold injection-casting method. The critical size for glass formation decreases to 2 mm when x=5 because Ni 2 SnZr phase precipitates readily. The addition of Sn is also effective in enhancing the stability of the supercooled liquid; a maximum supercooled liquid region of 48 K was attained for the Ni 61 Nb 30.5 Zr 3.5 Sn 5 alloy. Compression tests reveal that the Ni 61 Nb 33.5 Zr 3.5 Sn 2 alloy possesses the best mechanical properties, with yield strength ~3180 MPa, fracture strength ~3390 MPa and plastic strain ~1.3%. The fracture surfaces examined by scanning electron microscopy indicate that the alloys have a transition from ductility to brittleness in fracture behavior. The combination of high GFA, high thermal stability, high strength and compressive plasticity makes these alloys potentially attractive for engineering applications. Bulk metallic glasses (BMGs) have attracted much attention from scientists and engineers over the past few decades, since they possess such promising properties as high yield strength, hardness and elastic strain limit, along with relatively high fracture toughness, fatigue resistance and corrosion resistance [1][2][3]. In the case of Ni-based alloys, glassy rods up to several millimeters in diameter have been successfully fabricated from many alloy systems, such as, etc. These Ni-based bulk metallic glassy alloys have been reported to exhibit high strength (ranging up to 3000 MPa), high thermal stability (glass transition temperature generally around 880 K) [9,10], and excellent corrosion resistance [11]. The combination of superior properties enables them to have promising applications as engineering materials, such as for pressure sensors and micro-geared motors [12]. However, the achievement of a higher GFA for Ni-based amorphous alloys is still a challenging subject. So far the maximum dimension of Ni-based metallic glassy samples without noble elements is only 5 mm, which is much lower than that for other alloy systems, such as Zr-, Mg-, Ti-, Cu-, or Fe-based BMGs. Furthermore, most of the Ni-based BMGs exhibit a narrow supercooled liquid region (less than 40 K), which is not sufficient for processing. Thus, the development of new Ni-based BMGs with higher GFA as well as wide supercooled liquid region is of great importance. It was reported that BMG samples up to 3 mm were fabricated in the Ni-Nb-Sn [8] and Ni-Nb-Zr [13] alloy systems. The composition regions for glass formation in these simple ternary systems are located in the range of Ni 60 Nb 40-x Sn x (3

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Section: Resultsmentioning

confidence: 98%

Effect of Sn addition on the glass-forming ability and mechanical properties of Ni-Nb-Zr bulk metallic glasses

Zhang

Wang

et al. 2011

Chin. Sci. Bull.

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“…Deborah number was initially proposed by Reiner to describe the rheological behavior of materials [39]. Recently, Deborah number was also used for characterizing shear deformation instability of materials [40,41]. Here, we define the effective Deborah number De as follows:…”

Section: Characteristic Instability Time Within Sszmentioning

confidence: 99%

Enhancing surface integrity by high-speed extrusion machining

Liu

Cai

Shang

et al. 2016

Int J Adv Manuf Technol

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High-speed machining (HSM) is an advanced machining technology to form components. However, the poor surface integrity tends to appear due to chip flow instability in HSM. It is found that the surface integrity results from the competition of shear deformation instability between in primary shear zone (PSZ) and in separating shear zone (SSZ). To improve the surface integrity of machined components, the systematic high-speed extrusion machining (HSEM) experiments of magnesium alloy AZ31B with different constraint extrusion factors (CEFs) were carried out. The instability of shear deformation in PSZ is suppressed, and the microwaves on machined surface disappear when CEF is equal to or larger than a certain value. The measurements of the machined surface show that an improvement of surface integrity is achieved if CEF exceeds a certain value. The theoretical model for HSEM was established to elucidate the critical CEF. The underlying physics of surface integrity in HSEM is further revealed. The experimental results verify the validity of the theoretical model.

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“…However, when BMGs are loaded under an unconstrained condition, such as in uniaxial tension or simple shear, rather few of shear bands can be induced. Once the shear bands are formed, BMGs fail catastrophically within the main shear band and show little plasticity [9][10][11] , thus limiting the application of BMGs as engineering material. So, for the sake of perceiving the plastic instability behavior and applications in engineering, much effort has been devoted to the mechanism of formation and evolution of shear bands in BMGs [12][13][14][15][16][17][18] .…”

Section: Pile-up Around Indenter Is Usually Observed During Instrumenmentioning

confidence: 99%

Numerical study of pile-up in bulk metallic glass during spherical indentation

Dai

2008

Sci. China Ser. G-Phys. Mech. As

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Pile-up around indenter is usually observed during instrumented indentation tests on bulk metallic glass. Neglecting the pile-up effect may lead to errors in evaluating hardness, Young's modulus, stress-strain response, etc. Finite element analysis was employed to implement numerical simulation of spherical indentation tests on bulk metallic glass. A new model was proposed to describe the pile-up effect. By using this new model, the contact radius and hardness of Zr 41.2 Ti 13.8 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass were obtained under several different indenter loads with pile-up, and the results agree well with the data generated by numerical simulation.bulk metallic glass, spherical indenter, pile-up, contact radius, hardness Due to the unique physical, mechanical, and chemical properties, bulk metallic glasses (BMGs) are considered to be a class of very promising structure materials and will be adopted for application in various fields, such as civil astronautics, civil aeronautics and defense [1][2][3][4][5] . However, inhomogeneous flow of metallic glasses at room temperature is generally associated with highly localized shear bands [6,7] . The formation and interaction of shear bands control the mechanical properties, such as ductility and fracture toughness. Recently, Wang et al. have shown that high density, frequent interacting and arresting events of shear bands can lead to super-plasticity of BMGs at room temperature [8] . However, when BMGs are loaded under an unconstrained condition, such as in uniaxial tension or simple shear, rather few of shear bands can be induced. Once the shear bands are formed, BMGs fail catastrophically within the main shear band and show little plasticity [9][10][11] , thus limiting the application of BMGs as engineering material. So, for the sake of perceiving the plastic instability behavior and applications in engineering, much effort has been devoted to the mechanism of formation and evolution of shear bands in BMGs [12][13][14][15][16][17][18]

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Initiation and propagation of shear bands in Zr-based bulk metallic glass under quasi-static and dynamic shear loadings

Cited by 100 publications

References 58 publications

Effect of Sn addition on the glass-forming ability and mechanical properties of Ni-Nb-Zr bulk metallic glasses

Effect of Sn addition on the glass-forming ability and mechanical properties of Ni-Nb-Zr bulk metallic glasses

Enhancing surface integrity by high-speed extrusion machining

Numerical study of pile-up in bulk metallic glass during spherical indentation

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