Controlled Diffusion Solidification (CDS) of Al-Zn-Mg-Cu (7050): Microstructure, heat treatment and mechanical properties

Ghiaasiaan, Reza; Zeng, Xiaochun; Shankar, Sumanth

doi:10.1016/j.msea.2013.11.087

Cited by 65 publications

(22 citation statements)

References 28 publications

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“…pct Zn. It is noted that the Mg atoms in the white phase take up approximately one third of the total atoms in all cases (the same phenomenon has been observed for the near-equilibrium g precipitates with structure of MgZn 2 [5] ), and the compositions of these white phases are close to the concentration of r phase, [27] which can always be observed in as-cast AlZn-Mg-Cu alloys. The region D (Figure 2(b)) gives an average composition of the (Al + r) eutectic, and its alloying element concentrations are approximately half of those of r phase because of higher Al content from Al matrix to the compounds for the use of energy spectrum.…”

Section: A Phase Components and Solidification Paths Of The As-cast supporting

confidence: 71%

“…The Al:Cu atom ratios of the gray phases with few dissolved Zn and Mg atoms are approximately 2.0, and it is deduced to be Al 2 Cu (h) phase. [27] Moreover, a common phenomenon for the alloys containing h phase is that the h phase always adjoins the r phase, indicating the h phase was solidified as the (Al + r + h) eutectic.…”

Section: A Phase Components and Solidification Paths Of The As-cast mentioning

confidence: 99%

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Solidification Paths and Phase Components at High Temperatures of High-Zn Al-Zn-Mg-Cu Alloys with Different Mg and Cu Contents

Shu

Hou

Liu

et al. 2015

Metall Mater Trans A

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Studies were carried out systematically on a series of Al-8.5 wt pct Zn-xMg-yCu alloys (x is about 1.5, 2.0, and 2.5 wt pct, and y is about 1.5, 2.0, 2.5, and 2.9 wt pct). The effects of alloying elements Mg and Cu on the microstructures of as-cast and homogenized alloys were investigated using the computational/experimental approach. It shows that Mg(Zn,Al,Cu) 2 (r) phase can exist in all the as-cast alloys without any observable Mg 32 (Al,Zn) 49 /Al 2 Mg 3 Zn 3 (T) or Al 2 CuMg (S) phase, whereas Al 2 Cu (h) phase is prone to exist in the alloys with low Mg and high Cu contents. Thermodynamic calculation shows that the real solidification paths of the designed alloys fall in between the Scheil and the equilibrium conditions, and close to the former. After the long-time homogenization [733 K (460°C)/168 hours] and the two-step homogenization [733 K (460°C)/24 hours + 748 K (475°C)/24 hours], the phase components of the designed alloys are generally consistent with the calculated phase diagrams. At 733 K (460°C), the phase components in the thermodynamic equilibrium state are greatly influenced by Mg content, and the alloys with low Mg content are more likely to be in single-Al phase field even if the alloys contain high Cu content. At 748 K (475°C), the dissolution of the second phases is more effective, and the phase components in the thermodynamic equilibrium state are dominated primarily by (Mg + Cu) content, except the alloys with (Mg + Cu) Z 4.35 wt pct, all designed alloys are in single-Al phase field.

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Section: A Phase Components and Solidification Paths Of The As-cast supporting

confidence: 71%

Section: A Phase Components and Solidification Paths Of The As-cast mentioning

confidence: 99%

Solidification Paths and Phase Components at High Temperatures of High-Zn Al-Zn-Mg-Cu Alloys with Different Mg and Cu Contents

Shu

Hou

Liu

et al. 2015

Metall Mater Trans A

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“…Such alloys are widely used in automobile applications due to their high strength-to-weight ratio and their technological importance as medium to high strength materials. [1][2][3][4][5][6] The microstructure and mechanical properties obtainable from these alloys are known to be influenced by the growth rate, addition of the alloying elements, and heat treatment procedures.…”

Section: Introductionmentioning

confidence: 99%

“…[1] through [3], exponent value of V for k 1 is 0.25, and exponent values of V for k 2 changes from 0.5 to 0.66 from Eqs. [4] through [7].…”

Section: Introductionmentioning

confidence: 99%

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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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The role of indium in the activation of aluminum alloy galvanic anodes

Pourgharibshahi

Lambert

2015

Materials & Corrosion

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Despite six decades use of aluminum as a galvanic (sacrificial) anode, there remains a need for a better understanding of the underlying mechanisms for enhancing its efficient performance in cathodic protection systems. A few mechanisms have been proposed for the role of indium in the activation of Al‐Zn‐In anodes and there appears to be no general agreement on whether this element plays its depassivating role by modifying the bulk microstructure of the anode, chemical composition of its surrounding electrolyte or directly through doping the structure of the passive oxide film. These mechanisms have been critically reviewed to achieve a more comprehensive understanding of the role of indium in such applications. Moreover, the novel solidification processing called controlled diffusion solidification (CDS) has been introduced as an efficient way to surmount the poor castability of the anode alloy without any need for the addition of elements with detrimental effects on the electrochemical properties of the anode.

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Controlled Diffusion Solidification (CDS) of Al-Zn-Mg-Cu (7050): Microstructure, heat treatment and mechanical properties

Cited by 65 publications

References 28 publications

Solidification Paths and Phase Components at High Temperatures of High-Zn Al-Zn-Mg-Cu Alloys with Different Mg and Cu Contents

Solidification Paths and Phase Components at High Temperatures of High-Zn Al-Zn-Mg-Cu Alloys with Different Mg and Cu Contents

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

The role of indium in the activation of aluminum alloy galvanic anodes

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