[Zhang, P.; Li, S. X.; Zhang, Z. F.] Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Peoples R China.;Zhang, ZF (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Peoples R China;zhfzhang@imr.ac.cn

General relationship between strength and hardness

The mechanical properties of ex-situ and in-situ metallic glass matrix composites (MGMCs) have proven to be both scientifically unique and of potentially important for practical applications. However, the underlying deformation mechanisms remain to be studied. In this article, we review the development, fabrication, microstructures, and properties of MGMCs, including the room-temperature, cryogenic-temperature, and high-temperature mechanical properties upon quasi-static and dynamic loadings. In parallel, the deformation mechanisms are experimentally and theoretically explored. Moreover, the fatigue, corrosion, and wear behaviors of MGMCs are discussed. Finally, the potential applications and important unresolved issues are identified and discussed.

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Metallic glass matrix composites

Fe-based bulk metallic glasses: Glass formation, fabrication, properties and applications

A promising remedy to the failure of metallic glasses (MGs) by shear banding is the use of a dense network of glass-glass interfaces, i.e., a nanoglass (NG). Here we investigate the effect of grain size (d) on the failure of NG by performing molecular dynamics simulations of tensile-loading on Cu50Zr50 NG with d = 5 to 15 nm. Our results reveal a drastic change in deformation mode from a single shear band (d ∼ 15 to 10 nm), to cooperative shear failure (d ∼ 10 to 5 nm), to homogeneous superplastic flow (d ≤ 5 nm). Our results suggest that grain size can be an effective design parameter to tune the mechanical properties of MGs.

A transition from localized shear banding to homogeneous superplastic flow in nanoglass

Transport of carbon dioxide (CO2) via pipeline from the point of capture to a geologically suitable location for either sequestration or enhanced hydrocarbon recovery is a vital aspect of the carbon capture and storage (CCS) chain. This means of CO2 transport has a number of advantages over other means of CO2 transport, such as truck, rail, and ship. Pipelines ensure continuous transport of CO2 from the capture point to the storage site, which is essential to transport the amount of CO2 captured from the source facilities, such as fossil fuel power plants, operating in a continuous manner. Furthermore, using pipelines is regarded as more economical than other means of CO2 transport The greatest challenges of CO2 transport via pipelines are related to integrity, flow assurance, capital and operating costs, and health, safety and environmental factors. Deployment of CCS pipeline projects is based either on point-to-point transport, in which case a specific source matches a specific storage point, or through the development of pipeline networks with a backbone CO2 pipeline. In the latter case, the CO2 streams, which are characterised by a varying impurity level and handled by the individual operators, are linked to the backbone CO2 pipeline for further compression and transport. This may pose some additional challenges. This review involves a systematic evaluation of various challenges that delay the deployment of CO2 pipeline transport and is based on an extensive survey of the literature. It is aimed at confidence-building in the technology and improving economics in the long run. Moreover, the knowledge gaps were identified, including lack of analyses on a holistic assessment of component impurities, corrosion consideration at the conceptual stage, the effect of elevation on CO2 dense phase characteristics, permissible water levels in liquefied CO2, and commercial risks associated with project abandonment or cancellation resulting from high project capital and operating costs.

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A systematic review of key challenges of CO2 transport via pipelines

Catastrophic fracture with nearly zero tensile elongation at room temperature in bulk metallic glasses (BMGs) makes their future application as structural materials seem bleak. The instable localized shear banding with "work softening" under unconfined uniaxial tension should be responsible for the zero elongation. Here we show how to control the shear band and make it contribute to the macroscopic tensile plasticity of BMGs through designed artificial defects. By promoting the initiation of shear bands and hindering their instable propagation through introducing artificial defects, appreciable macroscopic tensile plasticity was successfully achieved in a conventional Zr-based BMG. Moreover, by designing the distribution of the defects to inhibit the intrinsic shear fracture, the nominal tensile strength and elongation of the BMG have been enhanced simultaneously. The principles for toughening BMG through designed artificial defects are proposed; accordingly, some strategies for designing future porous BMG materials with high mechanical performance were presented. (C) 2011 Elsevier B.V. All rights reserved.

Macroscopic tensile plasticity of bulk metallic glass through designed artificial defects

Plastic deformability of metallic glass by artificial macroscopic notches

Corrosion fatigue crack growth behavior of pipeline steel under underload-type variable amplitude loading schemes

A systematic study on the fracture surface of brittle Mg-, Fe-, and Co-based metallic glasses under compressive loading is approached and a fracture mechanism is proposed. Experimentally, the metallic glass samples are compressed into many small fragments, displaying an explosion fracture feature. Therefore, an energy equilibrium model is employed to describe the fracture processes of those brittle metallic glasses. Furthermore, some regular nanoscale steps, which were scarcely discovered, are found on the mirror region on their fracture surfaces. It is suggested that such nanoscale steps are associated with the energy distribution in metallic glasses and are created by the shear waves generated by the instability of crack propagation during the explosion rupture processes. Based on the comparison of experimental observations with numerical calculations, we recommend a novel model for interpreting the development of nanoscale steps on the dynamic fracture surfaces of these brittle metallic glasses, which appropriately describes the experimental findings.

https://magnetic.nimte.ac.cn/uploadfiles/site12/20115/2011524102505314.pdf

Fracture mechanism of some brittle metallic glasses

The plasticity of Ti-based metallic glasses with different aspect ratios can be improved by introducing two semicircular notches on the edges of the samples, owing to the interactions of shear bands (SBs) under conventional compression tests. The interaction of SBs can be ascribed to the easy initiation of SBs around the notches due to the large stress gradient, and the consequent blocking effect of notches on the propagation of shear bands. Additionally, the current findings provide a new way to understand the physical nature for the plastic deformation behavior of some brittle metallic glasses and supply an effective approach to enhance the plasticity to some extent.

Jiaxi Zhao

Papers

Macroscopic tensile plasticity of bulk metallic glass through designed artificial defects

Plastic deformability of metallic glass by artificial macroscopic notches

Corrosion fatigue crack growth behavior of pipeline steel under underload-type variable amplitude loading schemes

Fracture mechanism of some brittle metallic glasses

Deformation behavior and enhanced plasticity of Ti-based metallic glasses with notches