Modulation of Multiple Precipitates for High Strength and Ductility in Al-Cu-Mn Alloy

Abstract

The category and morphology of precipitates are essential factors in determining the mechanical behaviors of aluminum alloys. It is a great challenge to synthetically modulate multiple precipitates to simultaneously improve strength and ductility. In the present work, by optimizing the precipitations of the GP zone, θ’-approximant and θ’ phase for an Al-Cu-Mn alloy, a high tensile strength of 585 MPa with large elongation of 12.35% was achieved through pre-deformation and aging. The microstructure evolution pattern was revealed by detailed characterizations of scanning electron microscopy and transmission electron microscopy. It was found that such high tensile strength of the samples was due to a combination of strengthening by the high density of dispersive fine precipitates and dislocations, and the high elongation to failure was primarily attributed to the multimodal precipitates and elimination of precipitation-free zones along the grain boundaries. The strategy proposed here is a promising way of preparing ultra-strong Al-Cu-Mn alloys.

Effects of Sc Addition and Direct Aging Treatment on Microstructure and Hardness of AlSi10Mg Alloy

“…The coarsening of precipitates frequently happens as the aging time increases as reported elsewhere. [27,28] Under such microstructural configurations, the pinning effect on the dislocations movement gradually declined, resulting in a loss of hardness. According to Iwamura and Miura, [28] increasing the AlSc particle size may cause strength degradation of Al-Sc alloys in overaging conditions.…”

Experimental and Simulation Study for the Influence of Thermal Pre-Deformation on Subsequent Aging Precipitation Kinetics of Al-Zn-Mg-Cu Alloy

“…The driving force for the nucleation of the precipitates, as well as the solubility of the MgZn 2 phase in the Al-rich phase for Al-Zn-Mg-Cu alloys, can be calculated based on Equation (10) [40,41].…”

“…where c Zn and c Mg are equilibrium atomic concentrations of alloying elements Zn and Mg in the Al-rich matrix phase; A 0 is a constant; ∆H sol is the dissolution enthalpy of the precipitates. According to the sum of the equilibrium atomic concentration of Mg and Zn, which equals to 1.0% at 160 • C and 5.4% at 400 • C [26], as well as the experimental results for the specimen without pre-deformation, the dissolution enthalpy of the precipitates (∆H sol ) can be fixed at about 63.8 kJ/mol based on Equation (10). Other main thermo-physical parameters used in the calculation are shown in Table 3.…”

“…The effect of pre-deformation on subsequent artificial aging has been extensively studied for many heat treatable aluminum alloys [4][5][6][7][8][9][10][11]. The results show that pre-deformation can be positive or negative on the mechanical properties of aluminum alloys depending on the alloy composition, precipitate types and deformation parameters [9,[12][13][14][15].…”