Creep Deformation Mechanisms in Coarse-Grained Solid Solution Mg Alloys

Chung, Sung Wook; Watanabe, Hiroyuki; Kim, Woo Jin; Higashi, Kenji

doi:10.2320/matertrans.45.1266

Cited by 42 publications

(23 citation statements)

References 31 publications

(53 reference statements)

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“…Many researchers have suggested that the flow stress during climb-controlled dislocation creep in solid solution alloys such as Al-based alloys, [28][29][30] Cu-based alloys 31) and Mg-based alloys 32,33) is dependent on the stacking fault energy. The decrease in stacking fault energy due to the alloying in solid solution alloys usually improves the creep resistance.…”

Section: Discussionmentioning

confidence: 99%

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Effect of Small Addition of Zinc on Creep Behavior of Tin

Hamada

Uesugi

et al. 2010

Mater. Trans.

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Sn-based alloys with high creep resistance are required for soldering applications. This paper describes the effect of solid solution strengthening on the creep resistance of Sn-Zn alloys. The maximum solubility limit of Zn is 0.34 mass% in Sn. The creep behaviors of Sn, Sn-0.1 mass%Zn and Sn-0.4 mass%Zn were examined at 298 and 398 K under constant strain rates ranging from 1 Â 10 À4 to 1 Â 10 À2 s À1 . The creep resistance of Sn was improved significantly by the addition of a small amount of Zn owing to the solid solution strengthening. The creep resistance of Sn-0.4 mass%Zn was at the same level as that of Sn-37 mass%Pb. We obtained a stress exponent of about 7 and an activation energy of 41-45 kJ/mol, which indicates that the creep behavior was climb-controlled dislocation creep controlled by pipe diffusion. The finding that a small addition of Zn improves the creep resistance is useful for developing new Pb-free solders.

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Section: Discussionmentioning

confidence: 99%

“…The decrease in stacking fault energy due to the alloying in solid solution alloys usually improves the creep resistance. [28][29][30][31][32][33] It is explained that the root of solid solution strengthening in Sn-Zn alloys is also the decrease in the stacking fault energy due to the addition of Zn.…”

Section: Discussionmentioning

confidence: 99%

Effect of Small Addition of Zinc on Creep Behavior of Tin

Hamada

Uesugi

et al. 2010

Mater. Trans.

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“…3, two different situations are observed: Al in solution leads to a minor increase in creep resistance [77,78], even when ternary elements like Sn in MRI230D alloy shift the solute partitioning during solidification, increasing the final amount of Al in solid solution [77].…”

Section: Solid Solution Hardeningmentioning

confidence: 99%

Thermodynamics-based design of creep resistant Mg solid solutions using the Miedema scheme

Abaspour¹

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Most current creep resistant alloy design methods for Mg alloys aim at incremental strengthening of existing alloys such as AZ91 thorough addition of ternary and quaternary elements, or alternatively through RE's additions. The most remarkable improvements has been through either Mg-Y or recently developed Mg-Gd-Y-Zr and Mg-Y-Nd-Zr alloys, although still below the strength of MgTh alloys, which are being phase out due to Th's radioactivity.Many micromechanisms proposed to account for the observed improvements in either hardness or creep strength of Mg alloys including solid solution and/or precipitation hardening, dynamic precipitation, solute dragging/solute clustering and more importantly atomic size controlled diffusivity more often than not are little more than ad-hoc, after-the-fact explanations, valid at best for the particular system under consideration. Hence, extrapolation to other alloy-systems is either not possible or contradictory. In practice, a feasible path for systematic, either precipitationhardened or creep-resistant Mg alloys, selection and design is still lacking.The aim of the present work was to use atomic level thermodynamical arguments that suggest that extending the athermal regime through short range order (SRO) is a most feasible path to increasing the creep strength of Mg alloys. Potential solutes were sorted out and ranked based on their tendency to developing SRO using the Miedema's phenomenological scheme. The predictions were corroborated by experiments involving dilute binary alloys as well as through a collection of data from the literature.Monotonic compression and stress relaxation tests were carried out on specimens of 6 cast binary alloys with (at.%) 2.5 Al, 0.6 Sn, 2.2 Zn, 0.8 Gd, 1.3 Y and 0.9 Nd, and of a similarly cast AZ91D alloy for reference. The solute concentration in the binary alloys was kept deliberately low to limit precipitation hardening effects during the testing. Compression testing was carried out at 298K (25°C), 373K (100°C) and 453K (180°C) The relative tendency or lack of it, of most solutes to develop SRO rationalizes a number of observations in current multicomponent Mg alloys while it disputes the viability of several other micromechanisms often considered.The feasibility of strengthening HPDC Mg alloys through a combination of percolating eutectics and residual solute in solution, or, more generally, age hardenable alloys through either homogeneously nucleated, coherent with the Mg matrix, precipitates, or via internally ordered precipitates mimicking Mg-Th alloy system, is also considered by making parallels with either the Al-Zn or the Al-Cu alloy systems. Examples of these approaches were discussed using data from the literature, such as experiments on alloys combining Mn and Sc to introduce order in the soft Mn precipitates, or the use of Na to provide finely dispersed, homogeneously nucleated clusters with the aim of refining the subsequent precipitation in alloys such as Mg-Sn. III Declaration by authorThis thesis is composed of my or...

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“…Considering the obtained creep mechanism, it is possible to discuss how increasing Si content improves creep strength of these alloys. According to the literature, during climb controlled dislocation creep, high--temperature mechanical properties can be improved by decreasing of stacking fault energy, the forma- tion of particles with high thermal stability inside the grains, and forming intermetallic compounds in grain boundaries [20][21][22][23]. When the stacking fault energy is reduced, many dislocations are easily dissociated to partial dislocations with a wide stacking fault band.…”

Section: Impression Creep Testingmentioning

confidence: 99%

“…Intermetallic particles can act as barriers against the dislocations slipping inside the grains. They also can improve creep properties by hindering grain boundary sliding or preventing dislocation annihilation [20][21][22][23]. Wang et al [24] showed that stacking fault energy of Mg decreases from 99.3 to 50.5 mJ m −2 with doping 0.69 % Si.…”

Section: Impression Creep Testingmentioning

confidence: 99%

Impression creep properties of hypoeutectic Mg-xSi alloys

Badri¹,

Miresmaeili²,

Nami³

2021

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Impression creep behavior of as-cast Mg-xSi alloys (x = 0.5, 0.8, 1.2 wt.%) was studied under shear modulus-normalized stress values ranging from 0.009 to 0.016 at temperatures between 398 and 491 K. The results show that creep properties of these alloys are improved with increasing Si content under all the applied loads and temperatures, and Mg-1.2Si alloy has minimum creep rate and thus maximum creep resistance. It is attributed to the higher volume fraction of Mg2Si, which can reduce grain boundary sliding during the creep test. Stress exponent of all the alloys is between 4.06 and 7.09 in the temperature range of 398 to 447 K. It is changed from the range of 3.

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Creep Deformation Mechanisms in Coarse-Grained Solid Solution Mg Alloys

Cited by 42 publications

References 31 publications

Effect of Small Addition of Zinc on Creep Behavior of Tin

Effect of Small Addition of Zinc on Creep Behavior of Tin

Thermodynamics-based design of creep resistant Mg solid solutions using the Miedema scheme

Impression creep properties of hypoeutectic Mg-xSi alloys

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