Interactions between mechanically generated defects and corrosion phenomena of Zr-based bulk metallic glasses

Gebert, A.; Gostin, Petre Flaviu; Uhlemann, Margitta; Eckert, J.; Schultz, L.

doi:10.1016/j.actamat.2011.12.044

Cited by 42 publications

(25 citation statements)

References 46 publications

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“…At this site, chloride-induced pitting might be favored. This assumption is supported by Gebert et al (2012) who investigated the influence of mechanically generated defects on corrosion behavior of Zr59Ti3Cu20Al10Ni8 alloy in aqueous chloride-containing solutions. Their work reveals that shear banding takes place preferentially at corrosion pits, and conversely pitting is more likely at shear bands.…”

Section: Fractographic Analysismentioning

confidence: 50%

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Corrosion Fatigue Studies on a Bulk Glassy Zr-Based Alloy under Three-Point Bending

et al. 2017

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Corrosion fatigue (CF) tests were carried out on bulk glassy Zr52.5Cu17.9Al10Ni14.6Ti5 (Vitreloy 105) samples under load-controlled three-point bending conditions with a load ratio of R = 0.1 in 0.01 M Na2SO4 + 0.01 M NaCl electrolyte. During cyclic testing, the bar-shaped specimens were polarized in situ at constant potentials and the current was monitored. Three different anodic potentials within the interval between the pitting potential EP and the repassivation potential ER and three different load amplitudes were applied. In some cases, in situ microscopic observations revealed the formation of black corrosion products in the vicinity of the crack tip during anodic polarization. Fractographic analysis revealed a clear distinction between two modes of crack growth characterized by smooth dissolution induced regions on the one hand and slim fast fracture areas on the other hand. Both alternating features contributed to a broad-striated CF fracture surface. Moreover, further fatigue tests were carried out under free corrosion conditions yielding additional information on crack initiation and crack propagation period by means of the open circuit potential (OCP) changes. Thereby, a slight increase in OCP was detected after rupture of the passive layer due to bare metal exposed to the electrolyte. The electrochemical response increased continuously according to stable crack propagation until fracture occurred. Finally, the fracture surfaces of the CF samples were investigated by energy dispersive X-ray with the objective of analyzing the elemental distribution after anodic dissolution. Interestingly, anodic polarization at a near repassivation potential of −50 mV vs. saturated calomel electrode (SCE), which commands a constant electric potential of E = 0.241 V vs. standard hydrogen electrode (SHE), led to favorable effects on the fatigue lifetime. In conclusion, all results are conflated to a CF model for bulk glassy Vitreloy 105 under anodic polarization in chloridecontaining electrolyte and compared to the previously proposed stress corrosion mechanisms under similar conditions.

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Section: Fractographic Analysismentioning

confidence: 50%

“…The pitting corrosion behavior of Zr-based BMGs in chloridecontaining solutions has been widely investigated and is well understood so far (Mudali et al, 2004;Gebert et al, 2010Gebert et al, , 2012Gostin et al, 2015b). As already shown in Figure 7, cracks start preferentially at corrosion pits on the tensile loaded surface.…”

Section: Fractographic Analysismentioning

confidence: 93%

Corrosion Fatigue Studies on a Bulk Glassy Zr-Based Alloy under Three-Point Bending

et al. 2017

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“…For different alloy compositions an increase of hardness with increasing hydrogen content in the amorphous structure was evidenced and attributed to a restriction of shear band formation. This was compared with thermal relaxation effects causing embrittlement [34,46,69]. Wang et al [70] investigated glassy I-shaped notched Zr57Cu15.4Ni12.6Al10Nb5 (Vitreloy 106) specimen (made from 1.5 × 10 × 12 mm 3 plates) under sustained tensile load and severe hydrogen charging.…”

Section: Hydrogen Effectsmentioning

confidence: 99%

“…More recent studies demonstrated that shear steps at the surface produced by shear banding are preferred initiation sites for pitting corrosion. Gebert et al, carried out uniaxial compression loading to generate multiple shear bands in a bulk glassy Zr59Ti3Cu20Al10Ni8 alloy samples [34]. These samples were subsequently exposed to an aggressive 12 M HCl solution for 1 to 2 min.…”

Section: Pitting At Shear Steps and Shear Bandsmentioning

confidence: 99%

“…Before attempting to understand the role of such surface defects on the stress corrosion cracking initiation process, it is useful to first evaluate how these influence the corrosion behavior of Zr-based BMGs, especially pitting. In a recent study, Vickers micro-indents were used as model surface defects to study their impact on the pitting susceptibility of a typical Zr-based BMG, i.e., Zr59Ti3Cu20Al10Ni8 [34]. Multiple micro-indents were created by applying various loads from 25 to 2000 g on a mechanically polished surface.…”

Section: Pitting At Local Surface Defectsmentioning

confidence: 99%

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Stress-Corrosion Interactions in Zr-Based Bulk Metallic Glasses

Gostin

Eigel

Grell

et al. 2015

Metals

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Stress-corrosion interactions in materials may lead to early unpredictable catastrophic failure of structural parts, which can have dramatic effects. In Zr-based bulk metallic glasses, such interactions are particularly important as these have very high yield strength, limited ductility, and are relatively susceptible to localized corrosion in halide-containing aqueous environments. Relevant features of the mechanical and corrosion behavior of Zr-based bulk metallic glasses are described, and an account of knowledge regarding corrosion-deformation interactions gathered from ex situ experimental procedures is provided. Subsequently the literature on key phenomena including hydrogen damage, stress corrosion cracking, and corrosion fatigue is reviewed. Critical factors for such phenomena will be highlighted. The review also presents an outlook for the topic.

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In Situ Electrochemical Analysis during Deformation of a Zr‐Based Bulk Metallic Glass: A Sensitive Tool Revealing Early Shear Banding

et al. 2015

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In situ electrochemical experiments were carried out during quasi-static three-point bending of bulk glassy Zr 52.5 Cu 17.9 Ni 14.6 Al 10 Ti 5 alloy (Vit105) samples in air and in 0.01 M Na 2 SO 4 solution. Shear banding creating shear steps at surface break locally the naturally formed passive film resulting in a clear open circuit potential drop. Under potentiostatic polarization conditions, formation of shear steps causes narrow peaks in current density. By both methods, early shear banding can be detected before it can be inferred from macroscopic strain measurements.Most bulk metallic glasses (BMGs) show high strength values in combination with a large elastic deformation, which makes them very attractive for various applications. Concerning the quasi-static deformation behavior of fully amorphous bulk metallic glasses many investigations have been conducted and the versatile results are widely reported in literature. [1][2][3][4] But their lack of plasticity under mechanical loading, especially at tensile stresses, still poses an important drawback to their breakthrough as widely used structural materials. Particularly, the early stages of damaging are of great interest in this context. For this account, we developed a new technique taking advantage of discrete surface changes caused by shear banding, which are detectable by in situ electrochemical measurements. The prominent Zr-based BMG Vit105 was chosen as testing material in the current work, since it was identified as reliable target for complex mechanical analysis. [5] Versatile electrochemical investigations concerning the relation between corrosion and shear banding have been conducted for Zr-based amorphous alloys so far. In this context, Gebert et al. investigated the influence of mechanically generated surface defects on the pitting corrosion behavior of a Zr-based BMG in halide containing solutions. Moreover, they conducted a series of compression tests on samples with preformed corrosion pits to investigate the relationship between pitting and shear banding. [6] Wang et al. proposed a model which describes that pitting corrosion preferentially takes place at shear offsets. [7] Vit105 was recently analyzed concerning chemical breakdown events of the passive film without mechanical loading [8] and under static loading [9] both in a halide containing electrolyte. Since in the present study the pure deformation behavior of Vit105 bending samples is investigated, an inert 0.01 M Na 2 SO 4 solution was chosen for in situ electrochemical analysis. By the exploitation of the very sensitive electrochemical response of the Zr-based BMG to changes of the surface state, which are caused during deflection by the generation of small shear steps breaking the passive film, it is possible to detect and analyze the earliest stages of shear banding in situ during mechanical loading. ExperimentalThe Zr-based bulk glass-forming alloy Vit105 (Zr 52.5 Cu 17.9 -Ni 14.6

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Interactions between mechanically generated defects and corrosion phenomena of Zr-based bulk metallic glasses

Cited by 42 publications

References 46 publications

Corrosion Fatigue Studies on a Bulk Glassy Zr-Based Alloy under Three-Point Bending

Corrosion Fatigue Studies on a Bulk Glassy Zr-Based Alloy under Three-Point Bending

Stress-Corrosion Interactions in Zr-Based Bulk Metallic Glasses

In Situ Electrochemical Analysis during Deformation of a Zr‐Based Bulk Metallic Glass: A Sensitive Tool Revealing Early Shear Banding

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