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Indexed by:期刊论文

Date of Publication:2010-08-01

Journal:RARE METALS

Included Journals:SCIE、EI

Volume:29

Issue:4

Page Number:433-437

ISSN No.:1001-0521

Key Words:aluminum alloy; ageing treatment; microstructure; precipitate; fracture mechanism

Abstract:The tensile properties, electrical conductivity, and microstructure of the forged Al-7.1Zn-1.1Mg-1.6Cu-0.14Zr alloy were investigated after a two-step ageing treatment at 120 and 170 degrees C. The results indicate that the strength of the alloy reaches the peak value at 170 degrees C for 1 h during the second step ageing and then decreases sharply. However, the electrical conductivity value increases continuously with the second ageing time increasing. The fracture mechanism of the alloy is intergranular fracture for 1 h and then changes to dimple transgranular fracture later, and the toughness of the alloy is improved significantly. The phases of eta' and eta are major precipitates in the alloy under the two-step ageing condition. Discontinuous grain boundary precipitates and precipitate-free zones along the grain boundary are clearly observed.