Deformation Behavior, Microstructure and Mechanical Properties of new Al-Cu-Yb(Gd)-Mg-Mn-Zr Alloys

Deformation behavior, microstructure and mechanical properties of Al-Cu-Yb(Gd)-Mg-Mn-Zr alloy sheets are investigated. Based upon results of processing maps, optimum regimes for thermomechanical treatment at temperatures of 490-540 degrees C and speeds of 0.01-1 sec-1 are determined. Annealing of cold-rolled sheets at temperatures up to 180 degrees C leads to predominance of a strengthening effect due to aging over weakening from polygonization. Annealing of alloy sheets for 1 h at 400 degrees C forms a partly recrystallized structure with a clear reduction in hardness from 145 HV to 75 HV. After 2 hours of annealing at 150 degrees C, alloy combines a high yield strength of 412-417 MPa, a tensile strength of 441-449 MPa, and a good relative elongation of 2.7-3.2%. Sheet hardening followed by aging makes it possible to increase ductility by up to 5-8%, while the yield strength is 300-306 MPa with tensile strength of 364-389 MPa.