Effect of heat treatment on the deformation behavior of an Al–Cu alloy studied by in-situ synchrotron X-ray diffraction

Abstract

The effect of T6 heat treatment on microstructure evolution and mechanical properties of a multi-component hot-rolled (HR) Al–Cu alloy were studied by scanning/transmission electron microscopy (SEM/TEM) and electron back scattering diffraction (EBSD), and in-situ synchrotron X-ray diffraction (SXRD). The microstructure in HR alloy comprising Al9FeNi, Al7Cu2Fe, Al3CuNi, Al20Ti2Ce, Al3(TiZr), and Al2Cu; while the HR-T6 alloy containing Al9FeNi and Al7Cu2Fe. The tensile strength and elongation of HR-T6 alloy were improved simultaneously compared to HR alloy. After T6 heat treatment, the tensile strength of sample increased from 240 MPa to 309 MPa (28.75 % improvement) and the elongation increased from 4.1 % to 8.9 % (increased by 117 %). The strain evolution and load partition on behavior of the secondary phase and Al matrix upon tensile load were investigated by in-situ SXRD. The lattice strains of Al matrix and Al9FeNi phase of HR and HR-T6 samples increased from 1750με and 1480με to 2870με and 3490με, respectively, in the plastic deformation zone. The Al matrix and the secondary phase after T6 treatment have improved stress bearing capacity, especially for Al9FeNi phase. The "hard" Al9FeNi phase exhibited higher stress of 377 MPa compared to the "soft" Al matrix (stress of 214 MPa). This work provides an insight into the tailoring of strength-ductility comprehensive understanding the deformation behavior of Al–Cu alloys.