Paper Titles
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The Effect of Heat Treatment and Mn, Cu and Cr Additions on the Structure of Ingots of Al-Mg-Si-Fe Alloys
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Through Thickness Microstructural Gradients in 7475 and 2022 Creep - Ageformed Bend Coupons
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Effect of Al3Ni and Mg2Si Eutectic Phases on Casting Properties and Hardening of an Al-7% Zn-3% Mg Alloy
p.413
Mechanical Properties of Dispersion-Hardened P/M Al-Mn-Cu-Mg-Zn Alloys at Elevated Temperature
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Effects of a Small Addition of Cu or Ge on the Microstructure and Mechanical Property of an Al-Si Alloy
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Quantitative Correlation between Strength, Ductility and Precipitate Microstructures with PFZ in Al-Zn-Mg(-Ag, Cu) Alloys
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3DAP Analysis and Computer Simulation of Nanocluster Formation in the Initial Aging Stage of Al-Zn Alloys
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Effect of Al3Ni and Mg2Si Eutectic Phases on Casting Properties and Hardening of an Al-7% Zn-3% Mg Alloy

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Abstract:

The formation of eutectics in Al–Zn–Mg–Ni and Al–Zn–Mg–Si systems is studied by means of metallography, DSC, EPMA, X-ray spectroscopy and thermodynamical calculations. Polythermal sections of the corresponding phase diagrams are constructed. The concentrations and temperatures of binary eutectic reactions L → (Al) + Al3Ni and L → (Al) + Mg2Si in quaternary alloys are determined. Nonequilibrium solidification in Al–7% Zn–3% Mg-based alloys ceases at approximately 480 °C. The alloys close by composition to binary eutectics have considerably improved casting properties as compared to the base Al–7% Zn–3% Mg composition. In particular, hot tearing susceptibility is much less in alloys with Al3Ni or Mg2Si. These results are corroborated by measurements of thermal contraction during solidification. The alloys containing binary eutectics exhibit much lower temperatures of contraction onset and less thermal strain is accumulated in the solidification range. Fine eutectic morphology enables fragmentation and spheroidization of intermetallic particles during annealing. The presence of Al3Ni and Mg2Si particles does not decrease the precipitation hardening effect associated with precipitation of the T′ (AlMgZn) phase. Improved casting properties and good mechanical properties of castings allow the application of Al–Zn–Mg alloys with binary eutectics formed by Al3Ni or Mg2Si as foundry alloys.

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Periodical:

Materials Science Forum (Volumes 519-521)

Pages:

413-418

DOI:

https://doi.org/10.4028/www.scientific.net/MSF.519-521.413

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Online since:

July 2006

Authors:

Nikolay A. Belov, V.V. Cheverikin, Dmitry G. Eskin, A.N. Turchin

Keywords:

Eutectic Phases, Hot Tearing, Phase Diagram, Thermal Contraction

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© 2006 Trans Tech Publications Ltd. All Rights Reserved

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