Effect of the Heating/Cooling Rate of Nonisothermal Aging on Microstructure and Mechanical Properties of 2050 Al-Li Alloy

The effect of the heating/cooling rates of nonisothermal aging (NIA) on microstructure and mechanical properties of 2050 Al-Li alloy are investigated. The 2050 Al-Li alloy is first solid solutioned and predeformed and then heated from 130 to 220 degrees C at different rates of 20, 30 degrees C h-1, or 40 degrees C h-1 and then cooled to 150 degrees C. The results show that the mechanical properties of the alloy subjected to NIA treatment can be improved by adjusting the heating and cooling rate. When the heating and cooling rate is 30 degrees C h-1, the alloy achieves the best mechanical properties; the hardness, ultimate tensile strength (UTS), yield strength (YS), and elongation are 182.9 HV, 597, 571 MPa, and 9.6%, respectively. With the decrease of heating (or cooling) rate of NIA, the diameter and thickness of the T1 precipitate increase and the volume fraction decreases, resulting in the variation in mechanical properties. Therefore, herein, premier precipitation behavior and improved mechanical properties are both achieved by modifying the heating and cooling rate of NIA; the effect of the heating/cooling rate of NIA on the microstructure evolution of 2050 Al-Li alloy is revealed, and the underlying strengthening mechanism is investigated in detail. The heating/cooling rate of nonisothermal aging treatment can effectively regulate the microstructural characteristics of the T1 precipitate, and with the decrease of heating/cooling rate, the diameter and thickness of the T1 precipitate become larger and the volume fraction becomes smaller, which provides a reasonable explanation for the difference in mechanical properties under Orowan bypass mechanisms.image (c) 2024 WILEY-VCH GmbH