The nucleation and growth of S' precipitates in an aluminium-2.5% copper-1.2% magnesium alloy

Wilson, Robert N.; Partridge, P. G.

doi:10.1016/0001-6160(65)90043-x

Cited by 143 publications

(26 citation statements)

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“…[26] The S' precipitates can nucleate heterogeneously, particularly at dislocations and grain boundaries. [27,28] Some spherical Al 2 CuMg precipitates, a small fraction of Al 2 Cu precipitates, and some Al 3 Zr dispersoids were also observed.…”

Section: A Microstructure Characterizationmentioning

confidence: 93%

Effect of reinforcement-particle-orientation anisotropy on the tensile and fatigue behavior of metal-matrix composites

Ganesh

Chawla

2004

Metall Mater Trans A

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The effect of extrusion-induced particle-orientation anisotropy on the mechanical behavior of metal-matrix composites (MMCs) was examined. In this study, we have shown that this anisotropy has a significant influence on the tensile and fatigue behavior SiC particle-reinforced Al alloy composites. The preferred orientation of SiC particles was observed parallel to the extrusion axis, with the extent of orientation being highest for the lowest-volume-fraction composites. The composites exhibited higher Young's modulus and tensile strength along the longitudinal direction (parallel to the extrusion axis) than in the transverse direction. The extent of anisotropic behavior increased with increasing volume fraction, because of the increasing influence of the SiC reinforcement on the Young's modulus and tensile properties. The preferred orientation also resulted in anisotropy in the fatigue behavior of the composite material. The trends mirrored those observed in tension, with higher overall fatigue strengths for both orientations and a higher anisotropy with increasing volume fraction of particles. The influence of particle-orientation anisotropy and the resulting tensile and fatigue damage mechanisms is discussed.

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Section: A Microstructure Characterizationmentioning

confidence: 93%

Effect of reinforcement-particle-orientation anisotropy on the tensile and fatigue behavior of metal-matrix composites

Ganesh

Chawla

2004

Metall Mater Trans A

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“…Majimel et al [50] also observed similar needlelike precipitates about 28-nm long, although in a 2650 specimen aged for 19 hours at 190°C after prestraining by 2 pct, and proposed that they could be clusters, GPB/GPB2 zones, or a distinct phase S¢¢. Based on prior findings [4] and TEM observations, [32,50] the copper-and magnesium-containing precipitates in Figure 13(a) are considered to be small GPB/GPB2 zones. This result agrees with the present DSC analysis that suggests in-situ transformation of GPB to GPB2 in stage D.…”

Section: Differential Scanning Calorimetrymentioning

confidence: 82%

“…The precipitation sequence in aluminum alloys has been investigated using various methods that include dilatometry, [22] X-ray diffraction (XRD), [23][24][25][26][27] electrical resistivity measurements, [27,28] differential scanning calorimetry (DSC), [9,[29][30][31] transmission electron microscopy (TEM), [6,9,10,17,32,33] and atom probe field ion microscopy (APFIM). [34][35][36][37] Hunsicker, [22] in an attempt to determine the precipitation sequence during the aging of Al-Cu-Mg alloys from dilatometric measurements, assumed that the lattice parameter of the aluminum matrix was linearly related to solute concentrations and that the compositions of the precipitating phases did not change with time.…”

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confidence: 99%

Precipitation Behavior of AA2618

Lü

Kadolkar

Nakazawa

et al. 2007

Metall Mater Trans A

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The precipitation behavior of AA2618 was studied by a multitude of characterization techniques: microhardness testing, lattice parameter measurement through X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and atom probe field ion microscopy (APFIM). The matrix lattice parameter increased during the first 20 hours of natural aging, due to the formation of Cu clusters and decreased over the next 24 hours, due to the formation of Mg-rich clusters. Prior natural aging weakened subsequent artificial aging hardening at 180°C, 200°C, and 230°C, due to the cluster reversion that delayed the precipitation of strengthening phases. The matrix lattice parameter exhibited erratic changes during artificial aging that corresponded to the formation and partial dissolution of Guinier-Preston-Bagaryatsky (GPB) zones, the transformation of GPB zones to GPB2 zones, and the precipitation of S¢. The structural changes during the artificial aging of AA2618 occur in this sequence: supersaturated solid solution fi clusters + GPB fi GPB + GPB2 fi GPB2 + S¢ fi S¢+ S fi S.

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“…The 34 mm plate was not stretched, whereas the 38 and 45 mm plates were both given a 7% stretch prior to artificial ageing. The stretch generates dislocations which provide additional heterogeneous nucleation sites for the S/S phases during ageing (Wilson and Partridge 1965;Sen and West 1969). Slip planarity is expected to be less pronounced in material stretched before ageing due to the presence of a finer distribution of the S/S phases.…”

Section: Slip Planaritymentioning

confidence: 99%

A study aimed at determining and understanding the fracture behaviour of an Al–Li–Cu–Mg–Zr alloy 8090

Bregianos¹,

Crosky

Munroe

et al. 2010

Int J Fract

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The S-L fracture toughness of aluminiumlithium based alloys is generally poor and this has limited their applicability, particularly in aerospace where good damage tolerance is required. The low S-L toughness has been attributed variously to grain boundary precipitation, planar slip and lithium segregation. This work examined the S-L fracture behaviour of an 8090 Al-Li-based alloy in 34-45 mm plate. The results confirmed that the S-L fracture toughness decreases from the centre to the surface of plate material and increases with double ageing. Fracture is principally intergranular, with both ductile and brittle components occurring, but some transgranular fracture also occurs and this produces steps in the fracture plane. Changes in the relative proportions of brittle and ductile intergranular fracture, as well as in the amount of transgranular fracture, accompany the changes in toughness. However, A. C. Bregianos the decrease in fracture toughness across the plate is accompanied principally by an increase in the relative proportion of brittle intergranular fracture, while the toughening produced by double ageing is accompanied principally by an increase in the amount of transgranular fracture. Evidence of coarse slip, indicative of slip planarity, was seen from slip steps and dislocation structures. However, planar slip was seen only towards the centre of the plate and not towards the surface. The level of planar slip was not reduced markedly by double ageing. Texture varied with position across the plate. There were also a larger number of low angle boundaries towards the centre of the plate than towards the surface. The hardness did not change across the plate. The results could not be explained fully in terms of either the grain boundary precipitate theory or the planar slip model, but were generally consistent with the lithium segregation model. However, the basic tenet of this model is that the level of embrittlement is influenced by the grain boundary structure, and the results did not indicate a substantial difference between the boundaries that failed in a ductile manner and those which failed by brittle fracture. This suggests that the factors which affect lithium segregation may be more complex than originally envisaged.Keywords Short transverse · S-L orientation · Fracture behaviour · Toughness · 8090 Aluminiumlithium based aerospace alloy 123 142 A. C. Bregianos et al.

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The nucleation and growth of S' precipitates in an aluminium-2.5% copper-1.2% magnesium alloy

Cited by 143 publications

References 1 publication

Effect of reinforcement-particle-orientation anisotropy on the tensile and fatigue behavior of metal-matrix composites

Effect of reinforcement-particle-orientation anisotropy on the tensile and fatigue behavior of metal-matrix composites

Precipitation Behavior of AA2618

A study aimed at determining and understanding the fracture behaviour of an Al–Li–Cu–Mg–Zr alloy 8090

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