X-ray Thermo-Diffraction Study of the Aluminum-Based Multicomponent Alloy Al₅₈Zn₂₈Si₈Mg₆

Area of Science:

• Materials Science
• Metallurgy
• Solid-state Chemistry

Background:

• Novel multicomponent light alloys exhibit unique microstructures requiring detailed characterization.
• Previous computational studies (CALPHAD) on Al58Zn28Si8Mg6 alloy necessitate experimental validation.

Purpose of the Study:

• To experimentally determine the phase evolution of the Al58Zn28Si8Mg6 alloy during casting and heat treatment.
• To understand the influence of thermal history on phase formation and stability.

Main Methods:

• In situ X-ray diffraction (XRD) for real-time phase analysis.
• Differential scanning calorimetry (DSC) for thermal transition identification.
• Electron microscopy (EM) for microstructural examination.

Main Results:

• Eight distinct phases (α-Al, α'-Al, Zn, Si, Mg2Si, MgZn2, Mg2Zn11, SrZn13) identified between 30-380 °C.
• Multiple thermal transitions below 360 °C were precisely determined.
• Natural precipitation of the Zn phase observed after nine months; thermal history impacts MgZn2 and Mg2Zn11 phases.

Conclusions:

• The combined use of in situ XRD, DSC, and EM provides a comprehensive understanding of the alloy's high-temperature behavior.
• Experimental findings validate and complement CALPHAD predictions for this novel light alloy.
• The study establishes a foundation for optimizing heat treatments to control microstructure and properties.