Stress-Corrosion Interactions in Zr-Based Bulk Metallic Glasses

Gostin, Petre Flaviu; Eigel, Dimitri; Grell, Daniel; Uhlemann, Margitta; Kerscher, Eberhard; Eckert, J.; Gebert, A.

doi:10.3390/met5031262

Cited by 8 publications

(9 citation statements)

References 70 publications

(95 reference statements)

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“…Those were similarly measured for cast samples of type B. After surface polishing to remove the outermost plate regions with some unidentifiable crystalline phases (up to ∼100 µm depth), in all cases, only the broad diffuse diffracted intensity maxima which are characteristic for an amorphous phase were detected (Gostin et al, 2015c). Micro-CT of several cast specimens detected a limited number of small pores with sizes <50 µm.…”

Section: Impact Of Sample Homogeneity On Tensile and Bending Deformat...mentioning

confidence: 80%

“…An appropriate mixture of single constituent elements Zr, Cu, Ni, Al, and Ti with very high purity (purity ≥99.9%) was used for arc melting on a Cu hearth under highly purified Ti-gettered Ar atmosphere. To ensure a homogeneous chemical composition, the ingots with a mass of 20 g were re-melted at least three times (Gostin et al, 2015c).…”

Section: Bulk Metallic Glass Sample Preparationmentioning

confidence: 99%

“…For the analysis of SCC phenomena, rectangular bars were abrasively cut and metallographically prepared (0.25 µm finish) from cast BMG plates. For first studies with unnotched samples of alloy type "A, " their dimensions were 2.50 mm 3 × 2.00 mm 3 × 27.00 mm 3 (Gostin et al, 2015c). Later in the project, straight-through edge notched bar samples with S = 20 mm were made from alloy types "A" and "B, " respectively, as described in section "In Situ Analysis of Cracking in Air" and in Geissler et al (2019).…”

Section: Stress Corrosion Crackingmentioning

confidence: 99%

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Studies on Stress Corrosion Cracking of Vit 105 Bulk Metallic Glass

et al. 2020

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The project "Stress Corrosion Cracking of Zr-based Bulk Metallic Glasses" (SCC of Zr-BMGs) within PP1594 mainly dealt with mechanical-corrosive interactions and failure of this class of metastable materials. It focused on one of the most application-relevant zirconium (Zr)-BMG, Vit(reloy) 105, with composition Zr 52 . 5 Cu 17 . 9 Ni 14 . 6 Al 10 Ti 5 (at.%). Even though this BMG is known as an extraordinary glass former, the metallurgical processing is still a critical issue. In contrast to conventional processing, i.e., arc melting of master alloy ingots from single constituents, a different route using binary pre-alloys for the master alloys production was applied and led to superior mechanical properties upon mechanical testing under tensile and three-point-bending (3PB) conditions in air. As a reference and for a detailed understanding of failure, fracture, and cracking of Zr-based BMG in air, notched specimen 3PB experiments with in situ microscopic observation were done and the still controversial interpretation of the mechanical behavior of BMG in the framework of fracture mechanics was addressed. The specimen from the in situ 3PB tests served for transmission electron microscopy (TEM) investigations on the structural nature of shear bands in BMG on the atomistic scale. Altogether, complete crack paths could be observed and analyzed, and based on this, details of the shear band-driven crack growth are described. While in first SCC studies using a newly developed setup full cross section (3PB) bars were investigated, in recent in situ experiments, notched specimens were tested in 0.01 M NaCl, yielding strong evidence for a catastrophic failure due to hydrogen embrittlement (HE). The known susceptibility to pitting corrosion in halide-containing environments is only the initial stage for failure under SCC conditions. Once pitting is initiated, the local electrode potential is severely reduced. Further, the hydrolysis reaction of oxidized Zr 4+ to zirconyl ions ZrO 2+ during local BMG dissolution produces H + and, thus, a local acidic environment that enables proton reduction and hydrogen absorption in the stressed BMG region. The peculiar failure and fracture surface characteristics as well as the proven local reduction of the pH value in the vicinity of the notch during in situ experiments clearly account for the proposed HE-SCC failure mechanism.

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Section: Impact Of Sample Homogeneity On Tensile and Bending Deformat...mentioning

confidence: 80%

Section: Bulk Metallic Glass Sample Preparationmentioning

confidence: 99%

Section: Stress Corrosion Crackingmentioning

confidence: 99%

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Studies on Stress Corrosion Cracking of Vit 105 Bulk Metallic Glass

et al. 2020

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“…In contrast to previous studies [11], where hydrogen was added to the alloy by processing the melt in a H 2 -containing gas, hydrogen charging of samples was performed after quenching using a cathodic charging technique in a 0.5 mol/L sulfuric acid solution. The samples were charged at a current densitỹ 10 mA/cm 2 (lower than the critical current density for the formation of hydride [25]) for various charging times in order to control the dissolved hydrogen content (c H ). Hydrogen contents up to c H > 0.5 H/M (hydrogen-to-metal ratio) were investigated, with most studies focusing on c H ≤ 0.29 H/M where no specimen cracking was observed.…”

Section: Methodsmentioning

confidence: 99%

Effect of Hydrogen Charging on Pop-in Behavior of a Zr-Based Metallic Glass

Tian

Tönnies

Hirsbrunner

et al. 2019

Metals

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In this work, structural and mechanical properties of hydrogen-charged metallic glass are studied to evaluate the effect of hydrogen on early plasticity. Hydrogen is introduced into samples of a Zr-based (Vit 105) metallic glass using electrochemical charging. Nanoindentation tests reveal a clear increase in modulus and hardness as well as in the load of the first pop-in with increasing hydrogen content. At the same time, the probability of a pop-in occurring decreases, indicating that hydrogen hinders the onset of plastic instabilities while allowing local homogeneous deformation. The hydrogen-induced stiffening and hardening is rationalized by hydrogen stabilization of shear transformation zones (STZs) in the amorphous structure, while the improved ductility is attributed to the change in the spatial correlation of the STZs.

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“…Finally, the interplay between corrosion effects and mechanical properties of Zr-based metallic glasses are surveyed by P.F. Gostin et al [24].…”

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confidence: 99%

Metallic Glasses

Chan¹,

Sort

2015

Metals

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Metallic glasses are a fascinating class of metallic materials that do not display long-range atomic order. Due to their amorphous character and the concomitant lack of dislocations, these materials exhibit mechanical properties that are quite different from those of other solid materials [1,2]. For example, they can be twice as strong as steels, show more elasticity and fracture toughness than ceramics and be less brittle than conventional oxide glasses. In addition to their unique mechanical properties, metallic glasses have also demonstrated interesting physical and chemical properties. For example, some metallic glasses have been found to exhibit superior soft magnetic properties [3], good magnetocaloric effects [4] and outstanding catalytic performance [5], thus having potential for a widespread range of technological applications [6].Metallic glasses become relatively malleable when heated in the supercooled liquid region, allowing moulding and shaping with microscale precision by means of thermoplastic processing [7]. This has facilitated the development of diverse products based on these alloys, including sporting goods, medical and electronic devices and advanced defence and aerospace applications. However, in spite of their large elasticity, metallic glasses exhibit poor room-temperature macroscopic plasticity compared to polycrystalline metals [8]. This low plastic deformation, particularly evidenced when testing metallic glasses under tension, is related to the formation and rapid propagation of shear bands [2]. Therefore, novel routes to enhance plasticity of metallic glasses include procedures to hinder shear band propagation. This can be achieved, for example, by designing composite materials consisting of particles which act as second-phase reinforcements embedded in the amorphous matrix [9,10]. Other approaches towards toughening of metallic glasses have also been developed, such as the preparation of the so-called dual-phase amorphous metals [11], some specific surface treatments (e.g., laser or shot pinning) [12], or making their overall structure porous (i.e., metallic glass foams) [13]. OPEN ACCESS

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Stress-Corrosion Interactions in Zr-Based Bulk Metallic Glasses

Cited by 8 publications

References 70 publications

Studies on Stress Corrosion Cracking of Vit 105 Bulk Metallic Glass

Studies on Stress Corrosion Cracking of Vit 105 Bulk Metallic Glass

Effect of Hydrogen Charging on Pop-in Behavior of a Zr-Based Metallic Glass

Metallic Glasses

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