Influence of Mg content on quench sensitivity of Al–Zn–Mg–Cu aluminum alloys

• Published in: Journal of alloys and compounds Vol. 509; no. 13; pp. 4636 - 4642
• Main Authors: Deng, Yun-lai, Wan, Li, Zhang, Yun-ya, Zhang, Xin-ming
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 31.03.2011; Elsevier
• Subjects: Age hardening; Alloys; Aluminum base alloys; Al–Zn–Mg–Cu; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Cross-disciplinary physics: materials science; rheology; End-quenching; Exact sciences and technology; Grain boundaries; Hardness; Magnesium; Materials science; Microstructure; Physics; Precipitation; Quench sensitivity; Quenching; Quenching (cooling); Solid solution, precipitation, and dispersion hardening; aging; Treatment of materials and its effects on microstructure and properties; Al–Zn–Mg–Cu; Microstructure; Quench sensitivity; End-quenching; Aluminium base alloys; Cooling rate; Test method; Mechanical properties; Grain boundary precipitation; Hardness; Al-Zn-Mg-Cu; Age hardening; Quenching
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2011.01.147

► The end-quenching test is easy to reveal the quench sensitivity of Al–Zn–Mg–Cu aluminum alloys. ► The η particles undergo two precipitation processes successively during quenching: precipitation on grain boundaries and precipitation inside the grains. ► The quench sensitivity of Al–Zn–Mg–Cu aluminum alloys is influenced by the Mg content observably. The influence of Mg content on quench sensitivity of Al–8.0Zn– x(=1.0–2.0)Mg–1.6Cu alloys was investigated by an end-quenching test method. The depths of age hardening layer referenced to hardness retention values (e.g., 90%) of the end-quenched samples were used to describe the quench sensitivity. The results showed that the depths of age hardening layer decreased with increase of Mg content. The amount of the equilibrium-state MgZn 2 ( η) particles was the primary factor that determined the depths of age hardening layer. The η particles underwent two precipitation processes successively with decrease of cooling rate during quenching: precipitation on grain boundaries and precipitation inside the grains. The precipitation temperature peaks rose, and the ranges of the temperatures are extended with the increase of Mg content. A preliminary prediction has been made for the initial precipitation temperatures and the temperature peaks satisfying linear relation with Mg content (wt.%).