Modeling the age-hardening behavior of Al-Si-Cu alloys

Weakley-Bollin, S. C.; Donlon, W. T.; Wolverton, Christopher; Jones, J. W.; Allison, J.

doi:10.1007/s11661-006-0221-9

Cited by 80 publications

(31 citation statements)

References 25 publications

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“…[249] Whereas it is now possible to generate a microstructure containing both prismatic and basal plates in some magnesium alloys such as those based on the Mg-Gd-YZn system, and the basal plates in such a microstructure have a large aspect ratio, the aspect ratio and number density of the prismatic plates are much lower than those typical of precipitate plates formed in highstrength aluminum alloys. In high-strength precipitation-hardened aluminum alloys, the maximum hardness and yield strength is commonly associated with microstructures containing a high density of {100} a and {111} a precipitate plates of large aspect ratio (typically above 40:1) [245,250] (Figure 35), and these strengthening precipitates are often intermediate or equilibrium phases that are intrinsically stronger than G.P. zones and metastable precipitates formed in the early stage of aging.…”

Section: Microstructural Design For Higher Strengthmentioning

confidence: 99%

Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,351

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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Section: Microstructural Design For Higher Strengthmentioning

confidence: 99%

Precipitation and Hardening in Magnesium Alloys

Nie

2012

Metall Mater Trans A

1,351

519

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“…[1][2][3][4][5][6][7][8][9][10] However, these models only describe either the thermodynamics and kinetics for the precipitation process or the characteristics, sizes, and shapes of the precipitates on strengthening. Nothing had been taken into account to connect these two aspects until Shercliff and Ashby [11,12] made a first attempt to make a relationship between the process parameters (such as composition, aging temperature, and time) and the yield strength or hardness.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Age-Hardening Behavior of SiC/Al Metal Matrix Composites

Song

Chen

2007

Metall Mater Trans A

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A model for the age-hardening behavior of SiC/Al metal matrix composites has been developed to describe the variation of the yield strength with aging time. The model incorporates the heterogeneous nucleation and growth of the precipitates along the dislocations to describe the accelerated aging behavior. It has been shown that the size and volume fraction of the SiC particles as well as aging temperature influence the age-hardening behavior. Increasing the aging temperature accelerates the aging process by increasing the velocities of the total nucleation rate (the sum of the nucleation per unit time) and growth of the precipitates due to the enhanced diffusion velocity of the solute atoms. Decreasing the size and increasing the volume fraction of the SiC particles also accelerate the aging process by enhancing the total nucleation rate due to the increased dislocation density. It was found that the yield strengths have been well predicted by the model for both SiC-reinforced Al-Cu-Mg alloy and Al-Mg-Si alloy, which have plateshaped and needle-shaped precipitates, respectively.

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“…θ-Al 2 Cu has a structure (space group is I4/mcm) with lattice parameters a = 0.607 nm and c = 0.487 nm, and θ′ phase with tetragonal structure and a = 0.404 nm, c = 0.58 nm, the space group is I4m2 [26,27]. It has been confirmed that the ordered metastable θ′-phase imparts the largest strengthening effect in primary α-Al phase [28]. The θ′ precipitates have a platelet morphology with coherent (0 0 1) θ′ || {0 0 1} α-Al interfaces parallel to their broad faces.…”

Section: Effect Of Solution and Ageing Heat Treatment On The Microstrmentioning

confidence: 89%

Effect of heat treatment and Fe content on the microstructure and mechanical properties of die-cast Al–Si–Cu alloys

Yang

Fan

2015

Materials & Design

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The effect of solution and ageing heat treatment on the microstructure and mechanical properties of the die-cast Al-9 wt.%Si-3.5 wt.%Cu alloys containing 0.1-1.0 wt.% Fe was investigated. The results showed that the dendritic primary α-Al phase was varied from 20 to 100 μm in size and the globular α-Al grains were smaller than 10 μm in size. The Fe-rich intermetallics exhibited coarse compact or star-like shapes with the sizes from 10 to 20 μm and the fine compact particles at an average size of 0.75 μm. The solution treatment of the alloys could be achieved in a short period of time, typically 30 min at 510°C, which dissolved the Cu-rich intermetallics into the primary α-Al phase and spheroidised the eutectic Si phase. During the subsequent ageing treatment, numerous fine precipitates of θ′ and Q′ phases were formed to provide effective strengthening to the α-Al phase, significantly improving the mechanical properties. Therefore, Fe content in the die-cast Al-Si-Cu alloys needs to be controlled at a low level in order to obtain the improved ductility and strength under solution and aged condition.

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Modeling the age-hardening behavior of Al-Si-Cu alloys

Cited by 80 publications

References 25 publications

Precipitation and Hardening in Magnesium Alloys

Precipitation and Hardening in Magnesium Alloys

Modeling the Age-Hardening Behavior of SiC/Al Metal Matrix Composites

Effect of heat treatment and Fe content on the microstructure and mechanical properties of die-cast Al–Si–Cu alloys

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