Alloy design strategies for sustained ductility in Mg-based amorphous alloys – Tackling structural relaxation

Laws, Kevin J.; Granata, Davide; Löffler, Jörg F.

doi:10.1016/j.actamat.2015.08.077

Cited by 36 publications

(18 citation statements)

References 74 publications

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“…Substantial ductility has also been reported in Mg-rich (Mg > 85 at.%) Mg–Ni–Ca BMGs (1.2 mm diameter) 14 and in Mg–Ni–Y amorphous ribbons (20 um thick) 16 , keeping in mind that sample size can affect these results 23, 41 .…”

Section: Discussionmentioning

confidence: 86%

“…Some show exceptional glass-forming ability with critical casting sizes up to 27 mm 15 , placing them amongst the highest glass-forming alloy families. However, Mg-based BMGs have yet to realise their full potential in long-term load bearing or functional applications due to their intrinsically brittle nature and relatively short structural relaxation times 16 , 17 . To date, modest Mg-based ‘bulk’ glass ductility has only been observed in Mg-rich Mg–Ni–[Gd,Nd] 9 , 10 , and Mg–Ni–Ca 14 alloy systems.…”

Section: Introductionmentioning

confidence: 99%

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Electron-band theory inspired design of magnesium–precious metal bulk metallic glasses with high thermal stability and extended ductility

Laws

Shamlaye

Granata

et al. 2017

Sci Rep

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Magnesium-based bulk metallic glasses (BMGs) exhibit high specific strengths and excellent glass-forming ability compared to other metallic systems, making them suitable candidates for next-generation materials. However, current Mg-based BMGs tend to exhibit low thermal stability and are prone to structural relaxation and brittle failure. This study presents a range of new magnesium–precious metal-based BMGs from the ternary Mg–Ag–Ca, Mg–Ag–Yb, Mg–Pd–Ca and Mg–Pd–Yb alloy systems with Mg content greater than 67 at.%. These alloys were designed for high ductility by utilising atomic bond-band theory and a topological efficient atomic packing model. BMGs from the Mg–Pd–Ca alloy system exhibit high glass-forming ability with critical casting sizes of up to 3 mm in diameter, the highest glass transition temperatures (>200 °C) of any reported Mg-based BMG to date, and sustained compressive ductility. Alloys from the Mg–Pd–Yb family exhibit critical casting sizes of up to 4 mm in diameter, and the highest compressive plastic (1.59%) and total (3.78%) strain to failure of any so far reported Mg-based glass. The methods and theoretical approaches presented here demonstrate a significant step forward in the ongoing development of this extraordinary class of materials.

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Section: Discussionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Electron-band theory inspired design of magnesium–precious metal bulk metallic glasses with high thermal stability and extended ductility

Laws

Shamlaye

Granata

et al. 2017

Sci Rep

View full text Add to dashboard Cite

show abstract

“…differential scanning calorimetry (DSC) profiles of selected Mgbased BMGs. A clear glass transition (T g ) and subsequent crystallisation reaction can be seen in each instance, with considerable relaxation events (beta relaxation) prior to T g evident in most compositions, as also seen in other Mg-Cu BMG alloys[45].These Mg-based BMGs exhibit glass transition and crystallisation temperatures considerably lower than those of other Mg-Cu-RE BMGs, and are again more closely akin to the Mg-Cu-Ca[18] or even Mg-Zn-Ca[46] BMGS. Of particular note, the Mg 55 Cu 36 Yb 9 BMG has a very low T g of 95 °C, but nonetheless this alloy has the largest supercooled liquid region (SCLR), ΔT x (= T x -T g ) of 30 °C, of all the Mg-based BMGs, indicating the best processing window available for thermoplastic forming.Relative to the glass forming indicators T rg and γ, Mg-based alloys here exhibit quite low values compared to other glass-forming systems.…”

mentioning

confidence: 71%

Exceptionally broad bulk metallic glass formation in the Mg–Cu–Yb system

2017

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This study presents an extensive series of novel bulk metallic glasses (BMGs) which broadly span all three corners of the Mg-Cu-Yb ternary system. Over 30 alloys were synthesised within a wide composition range from (at.%): Mg: 13 -55, Cu: 17.5 -45.5, and Yb: 9 -70. In terms of composition, this ternary system is considered to be one of the broadest for bulk glass formation known -this probably due to the three elements' thermodynamic compatibility and unique combinations of atomic radii, which generate specific, favoured structural topologies. The investigation reports the design method, critical casting size, thermophysical characteristics and mechanical properties of these new BMGs.

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“…Most of these, however, are predicted to be brittle. This is not surprising, considering that the Poisson's ratio of pure elemental Ca is 0.31 and Mg is 0.29 [70]; and many of the Ca-and Mg-based metallic glasses studied experimentally exhibit brittle behavior [77][78][79]. Moreover, some glasses have shown bending ductility in ribbon form after production, but embrittle at room-temperature after only a few days or weeks [76,79].…”

Section: Al Camentioning

confidence: 99%

Metallic glasses for biodegradable implants

et al. 2019

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Metallic glasses are excellent candidates for biomedical implant applications due to their inherent strength and corrosion resistance. Use of metallic glasses in structural applications is limited, however, because bulk dimensions are challenging to achieve. Glassforming ability (GFA) varies strongly with alloy composition and becomes more difficult to predict as the number of chemical species in a system increases. Here we present a theoretical model -implemented in the AFLOW framework -for predicting GFA based on the competition between crystalline phases, and apply it to biologically relevant binary and ternary systems. Elastic properties are estimated based on the rule of mixtures for alloy systems that are predicted to be bulk glass-formers. Focusing on Ca-and Mg-based systems for use in biodegradable orthopedic support applications, we suggest alloys in the AgCaMg and AgMgZn families for further study; and alloys based on the compositions: Ag0.33Mg0. 67, Cu0.5Mg0.5, Cu0.37Mg0.63 and Cu0.25Mg0.5Zn0.25. arXiv:1902.00485v1 [cond-mat.mtrl-sci]

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Alloy design strategies for sustained ductility in Mg-based amorphous alloys – Tackling structural relaxation

Cited by 36 publications

References 74 publications

Electron-band theory inspired design of magnesium–precious metal bulk metallic glasses with high thermal stability and extended ductility

Electron-band theory inspired design of magnesium–precious metal bulk metallic glasses with high thermal stability and extended ductility

Exceptionally broad bulk metallic glass formation in the Mg–Cu–Yb system

Metallic glasses for biodegradable implants

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