Enhanced Tensile Plasticity in Ultrafine Lamellar Eutectic Al-CuBased Composites with α-Al Dendrites Prepared by Progressive Solidification

In this paper, a new class of Al-Cubased composites which combine the ultrafine lamellar eutectic matrix (alpha-Al + theta-Al2Cu) and micron-sized primary alpha-Al dendrites was prepared by progressive solidification. By adjusting the alloy composition and solidification process, the formation of favorable microstructural and micromechanical features can be achieved. The ultrafine lamellar eutectic composite Al94Cu6 exhibits excellent mechanical properties with 472 MPa fracture strength and 7.4% tensile plastic strain. The plasticity of the ultrafine lamellar eutectic composite relies on the volume fraction and work hardening ability of micron-scale primary phase. The present results provide a new perspective for improving the plasticity of the ultrafine lamellar eutectic alloys.