Heat treatment of 7xxx series aluminium alloys—Some recent developments

Quench sensitivity of Al–Mg–Si alloys: A model for linear cooling and strengthening

“…For most commonly used alloys such as the Al-Mg-Si (6xxx) and the Al-Zn-Mg-(Cu) (7xxx) alloys, age hardening response can be seriously affected by the cooling rate from solution annealing (e. g. [1][2][3][4][5][6][7][8][9]; and also toughness can be reduced due to reduced cooling rate [10]. To achieve optimal mechanical properties, precipitation during quenching must be fully suppressed, and this is achieved only if the alloy is cooled with the upper critical cooling rate or faster (e. g. [4,8,7]). However, fast cooling can induce residual stresses (e. g. [11][12][13]), and hence, in order to obtain an optimal balance between strength and residual stresses / distortion, cooling from solution annealing should be done with the upper critical cooling rate or slightly faster.…”

Modeling over-ageing in Al-Mg-Si alloys by a multi-phase CALPHAD-coupled Kampmann-Wagner Numerical model

“…The formation of the equilibrium precipitate phase is preceded by a series of metastable ones due to their ease of nucleation. Examples include the needle β'' precipitate in Al-Mg-Si [2], the plate θ' precipitate in Al-Cu [3], the platelet η' precipitate in Al-Zn-Mg [4], and the lath S' precipitate in Al-Cu-Mg alloys [5]. It is these metastable precipitates rather than their stable counterparts that are contributing to peak hardening.…”

Mechanical properties analysis of Al-9Zn-5Cu-4Mg cast alloy by T5 heat treatment

“…Zinc combined with copper and / or magnesium will generate the heat-treatable compositions which contributed to the increased hardness and strength in the heat treatment because the presence of four major intermetallic phases that are expected in commercial AlZn-Cu-Mg alloys including η (MgZn2), T (Al2Zn3Mg3), S (Al2CuMg), θ (Al2Cu), Al7Cu2Fe, Al13Fe4, and Mg2Si phases [4][5][6]. T and η phase are often present in solid solution with the presence of the four elements [10,11].…”

“…fracture toughness and fatigue resistance), modulus, strength, and ductility. These important properties can be produced through a variety of alloys, the exact process or a combination of both [5].…”