Relationship between cooling rate, microstructure evolution, and performance improvement of an Al–Cu alloy prepared using different methods

Abstract

The relationship between the cooling rate and microstructure evolution and the performance improvement of an Al–4.5 wt% Cu alloy prepared using different casting methods was investigated. The microstructure evolution, solute element distribution, and mechanical properties of specimens prepared using different cooling rates were systematically investigated using multi-scale optical microscopy, scanning electron microscopy, transmission electron microscopy, tensile testing, and hardness testing. Upon increasing the cooling rate from 1.65 to 117.3 K s−1, the average grain size, secondary dendrite arm spacing, and width and area fraction of eutectic phases significantly decreased, and the density of the precipitated phase, super-saturation degree of solute elements, and mechanical properties improved. Through a combination of grain-boundary, solid-solution, and precipitation strengthening, the cooling rate indirectly affected the mechanical properties of the heat-treated alloy sheets. The Al−4.5 wt% Cu alloy prepared by twin-roll casting under a cooling rate of 117.3 K s−1 exhibited a strength between 145.33 and 321.79 MPa and an elongation of 11.65%, demonstrating its potential as a high-performance aluminium alloy.