Effects of precipitate shape and orientation on dispersion strengthening in magnesium alloys

Nie, Jian Feng

doi:10.1016/s1359-6462(02)00497-9

Cited by 1,107 publications

(328 citation statements)

References 14 publications

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“…Strengthening precipitates, however, may be able to produce this effect. In particular, as already demonstrated by Nie, [7] precipitate's shape and habit has a profound effect on the strengthening against basal slip. A similar effect is also expected for other deformation modes.…”

Section: A Crystal Plasticity Modelingsupporting

confidence: 55%

“…This increase is a reasonable estimate of the maximum strengthening provided by precipitation according to Orowan calculations. [7,8] The predicted effect of strengthening all systems is to shift both the tensile and compressive flow stresses to higher values. As a result, the asymmetry ratio is reduced to 0.77 (at an effective plastic strain of zero).…”

Section: A Crystal Plasticity Modelingmentioning

confidence: 99%

“…[8,9] This analysis was based on the application of the Orowan equation to calculate stress required to bow dislocations around precipitates and a statistical approach to determine the mean number density and area of precipitates on a given type of slip plane. The method is an extension of that first applied to magnesium alloys by Nie, [7] where only basal slip was considered. This analysis in turn is based on earlier study on age hardenable aluminium alloys which also form precipitates in the form of plates or rods on rational habit planes (e.g., References 32-34).…”

Section: A Hardening Against Slipmentioning

confidence: 99%

“…One potential route to provide this differential strengthening is to take advantage of the fact that precipitation in magnesium alloys is also highly anisotropic, and precipitate's shape and habit are expected to have a large effect on the strengthening of any given slip system. [7][8][9] However, to reduce anisotropy and asymmetry, it is not sufficient to provide differential strengthening against slip alone because magnesium also deforms by twinning, and the f10 " 12g twinning mode in particular requires strong suppression to prevent its dominating yield behavior for loading conditions that produce c-axis tension. In a previous study, the authors have discussed the interaction between precipitates and f10 " 12g and suggested a simple semi-quantitative model for determining the effectiveness of a precipitate distribution in preventing twin growth.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Precipitate Shape and Habit on Mechanical Asymmetry in Magnesium Alloys

Robson

Stanford

Barnett

2012

Metall Mater Trans A

104

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Asymmetric yield behavior in tension and compression is a common and usually undesirable feature of wrought magnesium alloys. To prevent yield asymmetry, it is necessary to favor slip over twinning, as it is the unidirectional nature of twinning combined with the strong textures produced in wrought magnesium alloys that produce yield asymmetry. In this article, the potential to use precipitates to strengthen selectively against twin growth is discussed. The effect of precipitate's shape and habit on strengthening of slip and twinning is calculated using simple Orowan-based models. It is shown that basal plate precipitates, although being poor strengtheners against basal slip, are good strengtheners against twin growth. This is because they produce the maximum unrelaxed back-stress when they remain unsheared inside the twin. The predictions of the model have been validated against experiments for two alloys that form different precipitate types: AZ91 (basal plates). and Z5 (c-axis rods). Crystal plasticity modeling has been used to predict that an optimized distribution of basal plate precipitates is expected to strongly reduce yield asymmetry, even in strongly textured magnesium alloy.

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Section: A Crystal Plasticity Modelingsupporting

confidence: 55%

Section: A Crystal Plasticity Modelingmentioning

confidence: 99%

Section: A Hardening Against Slipmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Precipitate Shape and Habit on Mechanical Asymmetry in Magnesium Alloys

Robson

Stanford

Barnett

2012

Metall Mater Trans A

104

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“…31-Schematic diagrams showing (a and b) effects of the orientation of precipitate plates on interparticle spacing for dislocation slip on basal plane of the magnesium matrix phase (adapted from Refs. [20] and [241]), and (c) a prismatic plate sheared by dislocations gliding in basal plane of the magnesium matrix phase (reproduced from Ref. [20]).…”

Section: Mg Alloys Containing Shear-resistant Particlesmentioning

confidence: 99%

Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,394

519

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Magnesium alloys have received an increasing interest in the past 12 years for potential applications in the automotive, aircraft, aerospace, and electronic industries. Many of these alloys are strong because of solid-state precipitates that are produced by an age-hardening process. Although some strength improvements of existing magnesium alloys have been made and some novel alloys with improved strength have been developed, the strength level that has been achieved so far is still substantially lower than that obtained in counterpart aluminum alloys. Further improvements in the alloy strength require a better understanding of the structure, morphology, orientation of precipitates, effects of precipitate morphology, and orientation on the strengthening and microstructural factors that are important in controlling the nucleation and growth of these precipitates. In this review, precipitation in most precipitation-hardenable magnesium alloys is reviewed, and its relationship with strengthening is examined. It is demonstrated that the precipitation phenomena in these alloys, especially in the very early stage of the precipitation process, are still far from being well understood, and many fundamental issues remain unsolved even after some extensive and concerted efforts made in the past 12 years. The challenges associated with precipitation hardening and age hardening are identified and discussed, and guidelines are outlined for the rational design and development of higher strength, and ultimately ultrahigh strength, magnesium alloys via precipitation hardening.

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In‐Situ Scanning Electron Microscopy Comparison of Microstructure and Deformation Behavior between WE43‐F and WE43‐T5 Magnesium Alloys

Sano¹,

Yu²,

Davis³

et al. 2011

Magnesium Technology 2011

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Effects of precipitate shape and orientation on dispersion strengthening in magnesium alloys

Cited by 1,107 publications

References 14 publications

Effect of Precipitate Shape and Habit on Mechanical Asymmetry in Magnesium Alloys

Effect of Precipitate Shape and Habit on Mechanical Asymmetry in Magnesium Alloys

Precipitation and Hardening in Magnesium Alloys

In‐Situ Scanning Electron Microscopy Comparison of Microstructure and Deformation Behavior between WE43‐F and WE43‐T5 Magnesium Alloys

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