Effect of Zn Concentration on the Microstructure and Mechanical Properties of Al-Mg-Si-Zn Alloys Processed by Gravity Die Casting

Longfei Li, Shouxun Ji, Qiang Zhu, Yun Wang, Xixi Dong, Wenchao Yang, Stephen Midson, Yonglin Kang

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

The microstructure and mechanical properties of Al-8.1Mg-2.6Si-(0.08 to 4.62)Zn alloys (in wt pct) have been investigated by the permanent mold casting process. X-ray diffraction analysis shows that the τ-Mg32(Al, Zn)49 phase forms when the Zn content is 1.01 wt pct. With higher Zn contents of 2.37 and 3.59 wt pct, the η-MgZn2 and τ-Mg32(Al, Zn)49 phases precipitate in the microstructure, and the η-MgZn2 phase forms when the Zn content is 4.62 wt pct. Metallurgical analysis shows that the η-MgZn2 and τ-Mg32(Al, Zn)49 phases strengthen the Al-8.1Mg-2.6Si-(0.08 to 4.62)Zn alloys. After solutionizing at 510 °C for 180 minutes and aging at 180 °C for 90 minutes, the η′-MgZn2 phase precipitates in the α-Al matrix, which significantly enhances the mechanical properties. Addition of 3.59 wt pct Zn to the Al-8.1Mg-2.6Si alloy with heat treatment increases the yield strength from 96 to 280 MPa, increases the ultimate tensile strength from 267 to 310 MPa, and decreases the elongation from 9.97 to 1.74 pct.

Original languageEnglish
Pages (from-to)3247-3256
Number of pages10
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume49
Issue number8
DOIs
StatePublished - 1 Aug 2018

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