Recrystallization Performance of AA7050 Varied with Sc and Zr

Riddle, Yancy W.; Sanders, T. H.

doi:10.4028/www.scientific.net/msf.331-337.799

Cited by 32 publications

(21 citation statements)

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“…[19] Furthermore, the literature shows that scandium addition inhibits recrystallization and assists grain refinement of Al alloys. [7,20,21] The optical micrographs also reveal the presence of some coarse intermetallics in the alloys. The EDX analysis of these particles revealed that the irregular particles consist of Al-Fe-Cu and the spherical particles have Al-Mg-Cu.…”

Section: A Microstructurementioning

confidence: 94%

Influence of Heat Treatment and Scandium Addition on the Electrochemical Polarization Behavior of Al-Zn-Mg-Cu-Zr Alloy

Kannan

Raja

2007

Metall Mater Trans A

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In this study, the electrochemical polarization behaviors of Al-Zn-Mg-Cu-Zr (7010) alloy in three different heat treatments, namely, underaged, peak-aged, and overaged, were examined in 3.5 wt pct NaCl solution. Experimental results show that the cathodic current increases marginally in the order of underaged < peak-aged < overaged alloys, which has been attributed to an increase in copper content of the precipitates in general and the grain boundary precipitates (GBPs) in particular. The change in the precipitate chemical composition has been found to affect the anodic polarization behavior even in a more significant way. Thus, both the anodic polarization curves of underaged and peak-aged alloys exhibit two distinct breakdown potentials and current reversal immediately below the second breakdown potential, whereas such a phenomenon is found to be absent in the overaged alloy. The overaged alloy exhibits only one breakdown potential without any current reversal. Detailed study of the polarization data and corroded surfaces of the alloy shows that the anodic current reversal is due to H 2 evolution on the alloy surface just after the occurrence of passive film breakdown along the grain boundary. Notably, it is only those heat treatments that are prone to intergranular corrosion (IGC) seems to exhibit the tendency to reduce H + ions, when they are anodically polarized. The chemical composition of the precipitates that can be altered by heat treatments is responsible for this behavior. The addition of 0.25 wt pct scandium to type 7010 Al alloy did not show any improvement in the corrosion resistance of the alloy. The E corr of scandium containing alloy shifted toward the active direction as compared to the base alloy. Noticeably, the peak-aged scandium containing alloy also exhibited two distinct breakdown potentials in the anodic polarization curve similar to the peak-aged base alloy, thus revealing its susceptibility to IGC and pitting corrosion.

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Section: A Microstructurementioning

confidence: 94%

Influence of Heat Treatment and Scandium Addition on the Electrochemical Polarization Behavior of Al-Zn-Mg-Cu-Zr Alloy

Kannan

Raja

2007

Metall Mater Trans A

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“…The alloys are prone to recrystallization, however, in the interdendritic regions, where the number density of Al 3 Zr precipitates is small [20][21][22][23]. Several recent studies have aimed to minimize the extent of the precipitate-free interdendritic regions through multi-step annealing procedures [20,24,25] and other alloying additions, including Cu, Mg, Zn [21,26], Si, Fe, Mn [23,27] and Sc [22,[27][28][29][30][31][32][33] in 7xxx and other commercial wrought alloys.…”

Section: Introductionmentioning

confidence: 99%

Ambient- and high-temperature mechanical properties of isochronally aged Al–0.06Sc, Al–0.06Zr and Al–0.06Sc–0.06Zr (at.%) alloys

2011

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Ambient-and high-temperature precipitation strengthening are investigated in Al-0.06Sc, Al-0.06Zr and Al-0.06Sc-0.06Zr (at.%) alloys. Following solidification, Sc is concentrated at the dendrite peripheries while Zr is segregated at the dendrite cores. During isochronal aging, precipitation of Al 3 Sc (L1 2 ) commences between 250 and 300°C for Al-0.06Sc, and reaches a 429 MPa peak microhardness at 325°C. For Al-0.06Zr, precipitation of Al 3 Zr (L1 2 ) first occurs between 400 and 425°C and reaches a 295 MPa peak microhardness at 475°C. A pronounced synergistic effect is observed when both Sc and Zr are present. Above 325°C, Zr additions provide a secondary strength increase that is attributed to precipitation of Zr-enriched outer shells onto the Al 3 Sc precipitates, leading to a peak microhardness of 618 MPa at 400°C for Al-0.06Sc-0.06Zr. Upon compressive creep deformation at 300-400°C, Al-0.06Sc-0.06Zr exhibits threshold stresses of 7-12 MPa; these values may be further improved by optimal heat-treatments.

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“…4,5) Subsequent studies of Al-Sc alloys investigated their solidification behaviour, 6,7) recrystallization behaviour, 8,9) weldability, [10][11][12] tensile properties, [13][14][15][16] and fundamental mechanical properties [17][18][19][20][21] etc. Al-Sc alloys are used to fabricate numerous structural components for applications in the aircraft, automobile, transportation, sporting goods, and recreation fields.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Mechanical Response and Microstructural Evolution of High Strength Aluminum–Scandium (Al–Sc) Alloy

Lee

Chen

2006

Mater. Trans.

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The dynamic mechanical properties of high strength aluminum-scandium (Al-Sc) alloy are investigated using a compression split Hopkinson bar. Dynamic impact testing is carried out at nominal strain rates (abbreviated to strain rate hereafter) ranging from 1:2 Â 10 3 to 5:8 Â 10 3 s À1 at room temperature. The effects of strain rate on the mechanical properties, microstructural evolution and fracture characteristics are investigated and the relationship between the mechanical properties of the alloy and its microstructure is explored. The measured strainstress curves reveal that the dynamic mechanical behaviour of Al-Sc alloy is highly dependent on the strain rate. The flow stress, work hardening rate and strain rate sensitivity increase with increasing strain rate, but the fracture strain and activation volume decrease. The Zerilli-Armstrong fcc constitutive law is used to model the shear flow response of the Al-Sc alloy. A good agreement is found between the predicted and measured shear flow responses. The Al-Sc alloy specimens fracture as a result of shear band formation and crack propagation within the shear band. SEM observations indicate that the fracture features are dominated by a transgranular dimple-like structure. The density and depth of the dimples decrease with increasing strain rate. TEM microstructural observations reveal that the presence of Al 3 Sc precipitated particles in the matrix and at the grain boundaries prevents dislocation motion and leads to a significant strengthening effect. An analysis of the dislocation substructure indicates that a higher strain rate increases the dislocation density, thereby reducing the size of the dislocation cells. The variations of the dislocation cell structure reflect different degrees of strain rate sensitivity and activation volume, and correlate well with the impact flow stressstrain response.

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Recrystallization Performance of AA7050 Varied with Sc and Zr

Cited by 32 publications

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Influence of Heat Treatment and Scandium Addition on the Electrochemical Polarization Behavior of Al-Zn-Mg-Cu-Zr Alloy

Influence of Heat Treatment and Scandium Addition on the Electrochemical Polarization Behavior of Al-Zn-Mg-Cu-Zr Alloy

Ambient- and high-temperature mechanical properties of isochronally aged Al–0.06Sc, Al–0.06Zr and Al–0.06Sc–0.06Zr (at.%) alloys

Dynamic Mechanical Response and Microstructural Evolution of High Strength Aluminum–Scandium (Al–Sc) Alloy

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Recrystallization Performance of AA7050 Varied with Sc and Zr

Cited by 32 publications

References 0 publications

Influence of Heat Treatment and Scandium Addition on the Electrochemical Polarization Behavior of Al-Zn-Mg-Cu-Zr Alloy

Influence of Heat Treatment and Scandium Addition on the Electrochemical Polarization Behavior of Al-Zn-Mg-Cu-Zr Alloy

Ambient- and high-temperature mechanical properties of isochronally aged Al–0.06Sc, Al–0.06Zr and Al–0.06Sc–0.06Zr (at.%) alloys

Dynamic Mechanical Response and Microstructural Evolution of High Strength Aluminum&ndash;Scandium (Al&ndash;Sc) Alloy

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Dynamic Mechanical Response and Microstructural Evolution of High Strength Aluminum–Scandium (Al–Sc) Alloy