A new type of anti-phase boundaries in the T(Al20Cu2Mn3) phase and the pre-deformation effect on T phase precipitation

The anti-phase boundaries (APBs) in the T (Al20Cu2Mn3) phase and the interfaces of the T phase with an Al matrix were observed. The effects of pre-deformation on the precipitation behavior of T phase and hardening behavior of alloy were investigated by hardness measurement, mechanical tensile test, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Results show that two kinds of APBs exist in the T phase, i.e. {101}T and {301}T-type APBs. The first is commonly observed, while the latter is newly found and only coexists with the first to form a zig-zag shaped APB. Whatever its orientation relationships (ORs) with Al matrix and cross-section (CS) shape, the T phase always retains its interfaces constituted by {200}T, {101}T and {301}T planes. Pre-deformation increases the APBs in T phase and intensifies the irregularity of the CS shape of a T phase. Besides, it also promotes the nucleation and refines the size of the T phase during precipitation which enhances the mechanical properties of the alloy. •A new type of APB with slip displacement of 1/4 T is found in the T-phase.•The {301}T type APB coexists with {101}T type APB to form a zig-zag-shaped APB.•The T-phase interfaces are always constituted by {200}T, {101}T, and {301}T planes.•Pre-deformation increases APBs and causes a more irregular cross-section of T-phase.•Pre-deformation promotes the nucleation rate and refines T-phase.