Journal of Particle Science and Technology

Journal of Particle Science and Technology

Effect of Zr particles and RRA heat treatment on properties and grain boundary precipitation of 7055 Aluminum alloys

Document Type : Research Article

Authors
Mehdi Shakoory
Mohammad Esmailian
Morteza Taheri
Advanced Materials and New Technology Department, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran
10.22104/jpst.2026.7865.1287
Abstract
Due to its high strength and corrosion resistance, aluminum alloy 7055 is widely used in aerospace structures. However, its susceptibility to stress corrosion cracking (SCC) limits its performance. In this study, the combined effects of zirconium (Zr) addition and retrogression and re-aging (RRA) heat treatment on the microstructure, grain boundary precipitates, and stress corrosion resistance (SCR) of 7055 aluminum alloy were investigated. For property evaluation, microstructural characterization was carried out using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), while mechanical and stress corrosion tests were conducted according to ASTM standards. The results showed that Zr addition refined the grains and promoted the formation of Al3Zr particles within the matrix, inhibiting grain growth during heat treatment. RRA treatment accompanied by Zr addition improved the mechanical strength from 528 to 608 MPa and increased the stress corrosion resistance from 68 to 96 %. The combined effect of Zr addition and RRA treatment resulted in a more stable microstructure, with improved strength and resistance to stress-corrosion cracking.

Graphical Abstract

Effect of Zr particles and RRA heat treatment on properties and grain boundary precipitation of 7055 Aluminum alloys

Highlights

  • Retrogression and re-aging (RRA) heat treatment improves both the mechanical strength and the stress-corrosion resistance of the 7055 aluminum alloy.
  • After RRA heat treatment, better distribution and composition changes of the precipitates have been achieved.
  • With the addition of Zr, this element remains within the grains during heat treatment and inhibits grain growth, thereby improving the mechanical properties and corrosion resistance of the aluminum alloy.

Keywords
7055 Al Treatment
Zr in Al Grain boundary
Al 7055 Corrosion
Zr in Al 7055
Subjects

Copyright © 2025 The Author(s). Published by IROST.

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Journal of Particle Science and Technology
Volume 11, Issue 2
December 2025
Pages 93-100

  • Receive Date 16 November 2025
  • Revise Date 09 February 2026
  • Accept Date 14 February 2026