Y.L. Jia

Effects of Yb addition on microstructures and mechanical properties of 2519A aluminum alloy plate

Abstract The effects of Yb content on the microstructures and mechanical properties of 2519A aluminum alloy plate were investigated by means of tensile test, optical microscopy, transmission electron microscopy, scanning electron microscopy and X-ray diffractometer. The results show that addition of 0.17% (mass fraction) Yb increases the density of θ particles of the 2519A alloy plate and reduces the coarsening speed rate of θ phase at 300 °C. Therefore, tensile strength is enhanced from 483.2 MPa to 501.0 MPa at room temperature and is improved from 139.5 MPa to 169.4 MPa at 300 °C. The results also show that with the addition of 0.30% (mass fraction) Yb, the mechanical properties increase at 300 °C and decrease at room temperature. With Yb additions, the Al 7.4 Cu 9.6 Yb 2 phase is found whilst the segregated phases of as-cast alloys along grain boundaries become discontinuous, thin and spheroidized.

Precipitation kinetics of 2519A aluminum alloy based on aging curves and DSC analysis

Abstract The precipitation kinetics of 2519A aluminum alloy after different cold rolling reductions before aging was investigated by hardness test and differential scanning calorimetry (DSC). The activation energy was calculated according to DSC curves using single heating rate method. The microstructures of as-rolled and peak-aged alloys were observed by transmission electron microscopy (TEM). The result shows that the age hardenability reduces and the activation energy rises with increasing the reduction from 7% to 40%. Nonuniform dislocations are found in as-rolled alloy and inhomogeneous distribution of θ′ phase is revealed in peak-aged alloy when the reduction is 15%. The inhomogeneous distribution of θ′ phase may be related to the age hardenability reducing and activation energy rising.