Calculated phase diagrams and the corrosion of die-cast Mg–Al alloys

Liu, Ming; Uggowitzer, Peter J.; Nagasekhar, A.V.; Schmutz, Patrik; Easton, Mark; Song, Guang‐Ling; Atrens, Andrej

doi:10.1016/j.corsci.2008.12.015

Cited by 317 publications

(160 citation statements)

References 75 publications

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“…This shows the large influence of impurities on the biodegradation behaviour. Mg degradation is highly influenced not only by impurities (Hanawalt et al, 1942;Hofstetter et al, 2015a;Hofstetter et al, 2015b;Lee et al, 2009;Liu et al, 2009;Reichek et al, 1985;Yang et al, 2015), but also by alloys addition and grain size . Furthermore, the degradation conditions and the performance of the formed surface layer have also an impact (Walker et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

In vivo and in vitro degradation comparison of pure Mg, Mg-10Gd and Mg-2Ag: a short term study

Marco

Myrissa²,

Martinelli³

et al. 2017

eCM

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The purpose of this study was to compare short term in vitro and in vivo biodegradation studies with low purity Mg (> 99.94 %), Mg-10Gd and Mg-2Ag designed for biodegradable implant applications. Three in vitro testing conditions were applied, using (i) phosphate buffered saline (PBS), (ii) Hank's balanced salt solution (HBSS) and (iii) Dulbecco's modified eagle medium (DMEM) in 5 % CO 2 under sterile conditions. Gas evolution and mass loss (ML) were assessed, as well as the degradation layer, by elemental mapping and scanning electron microscopy (SEM). In vivo, implantations were performed on male Sprague-Dawley rats evaluating both, gas cavity volume and implant volume reduction by micro-computed tomography (µCT), 7 d after implantation. Samples were produced by casting, solution heat treatment and extrusion in disc and pin shape for the in vitro and in vivo experiments, respectively. Results showed that when the processing of the Mg sample varied, differences were found not only in the alloy impurity content and the grain size, but also in the corrosion behaviour. An increase of Fe and Ni or a large grain size seemed to play a major role in the degradation process, while the influence of alloying elements, such as Gd and Ag, played a secondary role. Results also indicated that cell culture conditions induced degradation rates and degradation layer elemental composition comparable to in vivo conditions. These in vitro and in vivo degradation layers consisted of Mg hydroxide, Mg-Ca carbonate and Ca phosphate.

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Section: Introductionmentioning

confidence: 99%

In vivo and in vitro degradation comparison of pure Mg, Mg-10Gd and Mg-2Ag: a short term study

Marco

Myrissa²,

Martinelli³

et al. 2017

eCM

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“…This statement is also supported by Table 1 which provides a compilation of corrosion rates for high-purity (HP) Mg [100][101][102][103][104][105][106][107] in comparison to corrosion rates measured for Mg alloys in recent research in solutions like 3% NaCl [49,58,70,76,77,88,89,98,. The corrosion rate of high purity Mg is $0.3 mm y À1 in such solutions, although individual measurements can give values up to 1.8 mm y À1 .…”

Section: Corrosion Of Mg Alloysmentioning

confidence: 60%

“…-32-rates for their wrought pure Mg much higher than the values quoted above for the corrosion of high-purity Mg. The reason was explained by Liu et al [104], and relates to the metallurgy of the wrought Mg studied by Prado et al [76,77]. This explanation is summarised in the next section.…”

mentioning

confidence: 97%

“…Particularly deleterious to the corrosion behaviour of Mg alloys are the impurity elements Fe, Ni, Cr and Co [1,2,4,5,9,104]. The corrosion rate is high when the impurity element concentration is greater than their tolerance limit.…”

Section: Impurity Elementsmentioning

confidence: 99%

“…The experiments showed that it was not. The works by Liu et al [104], Prado and co-workers [76,77] and Qiao et al [106] indicate that precipitation of Fe rich phases during heat treatment, solidification or during hot working can produce Mg that behaves as low-purity Mg even though the Fe concentration was below the tolerance limit for a casting.…”

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confidence: 99%

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Corrosion and stress corrosion cracking of magnesium alloys

Cao¹

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Magnesium (Mg) alloys are attractive for light-weight applications such as in the aerospace and automobile industries, due to their high strength-to-weight ratio. The widespread application of Mg alloys in automobiles can decrease fuel consumption through lightweighting, which benefits our environment. Mg alloys are also regarded as promising biodegradable implants for use in the human body. However, the poor resistance of corrosion and stress corrosion cracking (SCC) limits their more wide-spread application in both industry and medical application. It is therefore necessary to better understand the mechanisms and the important factors, which control Mg corrosion and SCC, and to find better ways to improve their corrosion and SCC performance. In this doctoral dissertation, an effort was made to understanding the following issues regarding the corrosion and SCC mechanisms, and behaviour of pure magnesium and magnesium alloys:(1) The corrosion behaviour of ultra-high-purity Mg in 3.5% NaCl solution saturated with Mg(OH) 2 (2) The corrosion behaviour of as-cast and solution-heat-treated binary Mg-X alloys in salt spray and 3.5% NaCl solution saturated with Mg(OH) 2 (3) Influence of hot rolling on the corrosion behaviour of several Mg-X alloys (4) The influence of casting porosity on the corrosion behaviour of Mg0.1Si (5) Stress corrosion cracking of several solution heat-treated Mg-X alloys (6) Stress corrosion cracking of several hot-rolled Mg-X alloys A range of advanced techniques were employed such as optical microscopy (OM), scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), electrochemical polarization, electrochemical impedance spectroscopy (EIS), gas collection of hydrogen evolution from corroding samples, and linearly increasing stress testing (LIST).For the ultra-high-purity Mg in 3.5% NaCl solution saturated with Mg(OH) 2 , the intrinsic corrosion rate measured with weight loss, P W = 0.25 ± 0.07 mm y -1 . The average corrosion rate measured from hydrogen evolution, P AH , was lower than that measured with weight loss, P W , attributed to dissolution of some hydrogen in the Mg specimen. The amount of dissolution under electrochemical control was a small amount of the total dissolution. A new hydride dissolution mechanism was suggested.For solution-heat-treated Mg-X alloys (X = Mn, Sn, Ca, Zn, Al, Zr, Si, Sr), corrosion rates did not meet the expectation that they should be equal to or lower than those of high-purity II Mg. There was circumstantial evidence that the higher corrosion rates were caused by the particles in the microstructure; the second phases had been dissolved.For the hot-rolled Mg-X alloys (X = Gd, Ca, Al, Mn, Sn, Sr, Nd, La, Ce, Zr or Si) in 3.5% NaCl solution saturated with Mg(OH) 2 , the corrosion rate for all Mg-X alloys (except Mg0.1Zr and Mg0.3Si) decreased after hot rolling, attributed to fine-grained alloys having a more homogeneous microstructure, and fewer, smaller second-phase particles. For Mg0.1Zr and Mg0.3Si, the corrosion rate increas...

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