Effect of Zn Content on the Microstructure and Properties of Super-High Strength Al-Zn-Mg-Cu Alloys

Chen, Ziyong; Mo, Yuanke; Nie, Zuoren

doi:10.1007/s11661-013-1731-x

Cited by 118 publications

(30 citation statements)

References 30 publications

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“…Zn and Mg contents in the dendrite were determined to be approximately constant, and naturally, these values are lower than the nominal values of the composition because the alloy first starts to solidify with lower composition values, so the dendrite has higher temperatures than the surrounding. [41] The solute piles up in front of the dendrite tip at the solid-liquid interface, and then the contents of Zn and Mg were reduced from the solid-liquid interface to liquid phase, and finally, the content of Zn and Mg become closer to the nominal composition (Figure 4).…”

Section: A Composition Analysis Of the Phases (Wdxrf And Edx Analysis)mentioning

confidence: 99%

Effect of Growth Rate on the Microstructure and Microhardness in a Directionally Solidified Al-Zn-Mg Alloy

Acer

Çadırlı

Erol

et al. 2016

Metall Mater Trans A

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The Al-5.5Zn-2.5Mg (wt pct) ternary alloy was prepared using a vacuum melting furnace and a casting furnace. Five samples were directionally solidified upwards at a constant temperature gradient (G = 5.5 K/mm) under different growth rates (V = 8.3-165 lm/s) in a Bridgman-type directional solidification furnace. The primary dendrite arm spacing, k 1 , secondary dendrite arm spacing, k 2 , and microhardness, HV, of the samples were measured. The effects of V on k 1 , k 2 and HV properties of the Al-Zn-Mg alloy were studied by microstructure analysis and mechanical characterization. Microstructure characterization of the alloys was carried out using optical microscopy, scanning electron microscopy, wavelength-dispersive X-ray fluorescence spectrometry, and energy dispersive X-ray spectroscopy. From the experimental results, it is found that the k 1 , k 2 values decrease, but HV values increase with the increase in V, and HV values decrease with the increase in k 1 and k 2 . Dependencies of dendritic spacing and microhardness on the growth rate were determined using linear regression analysis. The growth rate, microstructure, and Hall-Petch-type relationships obtained in this work have been compared with the results of previous studies.

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Section: A Composition Analysis Of the Phases (Wdxrf And Edx Analysis)mentioning

confidence: 99%

Effect of Growth Rate on the Microstructure and Microhardness in a Directionally Solidified Al-Zn-Mg Alloy

Acer

Çadırlı

Erol

et al. 2016

Metall Mater Trans A

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“…In order to meet the raising demands of higher strength, fracture toughness, and improved stress corrosion cracking (SCC) resistance, a series of 7XXX aluminum alloys has been developed through changes in composition (mainly Zn/Mg/Cu ratios), heat treatments and processing (Koyama 2010).The strength of 7XXX alloys is mainly attributed to the presence of coherent  phase (MgZn 2 ) in the grain interior and non-coherent  phase along the grain boundaries (Immarigeon et al 1995). Hence, higher Zn-Mg ratio not only increases the formation of MgZn 2 that strengthens the alloys after a heat treatment but also makes the alloys prone to SCC (Chen et al 2013). Gruhl and Metallkd (1984) reported that the SCC susceptibility of 7XXX aluminum alloys increases with increasing Zn content.…”

Section: Introductionmentioning

confidence: 99%

Influences of hydrogen on deformation and fracture behaviors of high Zn 7XXX aluminum alloys

et al. 2016

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Hydrogen degrades the mechanical properties of high strength 7XXX aluminum alloys in two ways: (i) degrades the mechanical properties by hydrogen embrittlement, and (ii) partitioned into micropores as molecular hydrogen and make contributions to ordinary ductile fracture. The multifaceted effects of hydrogen on the mechanical properties of high Zn content 7XXX aluminum alloys during deformation and fracture is studied by using synchrotron X-ray microtomography. Our results have revealed that the hydrogen susceptibility has increased with increasing the Zn amount. High concentration of hydrogen was induced by the EDM wire eroder. This high concentrated hydrogen induces quasi-cleavage fracture and restricts the growth of 2 micropores during ductile deformation. The threshold concentration of hydrogen ahead of the crack tip for the nucleation of quasi-cleavage feature was estimated to be 13 cm 3 /100 g Al.

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“…Hydrogen embrittlement in 7XXX aluminum alloys has been recognized as one of the longstanding technological challenges in the aerospace industry. Until now, many efforts have been carried out by various researchers to increase the strength and toughness as well as to improve the hydrogen embrittlement resistance of 7XXX aluminum alloys through: (i) changes in composition (mainly Zn/Mg/Cu ratios) [4][5][6][7][8][9], (ii) minimizing the impurity level [10][11][12], (iii) heat treatment and processing [13][14][15][16][17][18][19][20]. Consequently, a range of microstructural features can be resulted, which can act as H trapping sites.…”

Section: Introductionmentioning

confidence: 99%

Combined microtomography, thermal desorption spectroscopy, X-ray diffraction study of hydrogen trapping behavior in 7XXX aluminum alloys

Bhuiyan

Toda

Zhang

et al. 2016

Materials Science and Engineering: A

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In the present study, combined thermal desorption spectroscopy (TDS), microtomography and X-ray diffraction study has been carried out to identify the hydrogen trap sites in 7XXX aluminum alloys. Through constant heating rate TDS experiments, three distinct trap states have been identified. It is revealed that micropores are the predominant hydrogen trap site in alloys with medium hydrogen content, whereas grain boundaries is the major hydrogen trap site in alloys with low and high hydrogen content. We have clarified that the rate of trap site occupancy in grain boundaries is high compared to dislocations and vacancies. Such high hydrogen coverage at grain boundaries indicates that the hydrogen-assisted fracture would be intergranular.

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Effect of Zn Content on the Microstructure and Properties of Super-High Strength Al-Zn-Mg-Cu Alloys

Cited by 118 publications

References 30 publications

Effect of Growth Rate on the Microstructure and Microhardness in a Directionally Solidified Al-Zn-Mg Alloy

Effect of Growth Rate on the Microstructure and Microhardness in a Directionally Solidified Al-Zn-Mg Alloy

Influences of hydrogen on deformation and fracture behaviors of high Zn 7XXX aluminum alloys

Combined microtomography, thermal desorption spectroscopy, X-ray diffraction study of hydrogen trapping behavior in 7XXX aluminum alloys

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