MICROSTRUCTURAL EVALUATION OF AN Al-Cu-Mg ALLOY AFTER ADDITION OF RARE EARTH METAL UNDER SPARK PLASMA SINTERING CONDITIONS

In the past couple of decades, a rapidly growing commercial interest had been shown in the development of high- strength Al-Cu-Mg aluminium alloys. The present study shows that the addition of Rare Earth (RE) enhances the microstructure and mechanical properties of 2024 Aluminium Alloy (AA). Samples of 2024 AA with RE ranging from 1% to 5 wt% are fabricated by Spark Plasma Sintering (SPS). Hardness of the samples is determined using Vickers hardness testing machine. The metallurgical characterization of the samples is evaluated by Optical Microscopy (OM), and Field Emission Scanning Electron Microscopy (FE-SEM). Unreinforced 2024 AA sample is also fabricated as a benchmark to compare its properties with those of the composite developed. It is found that the RE addition mainly alters the precipitation kinetics and gradually increases the above mentioned properties. The highest hardness, yield strength and ultimate tensile strength achieved are 121 Hv, 298 MPa and 340 MPa. The percentage of elongation decreased with increase in RE wt%. High density is achieved in the samples fabricated by spark plasma sintering. Density of composites is attributed to its high heating and cooling rate achieved by SPS. Heating is done through joule heating which enables to achieve very high temperature in a very short period of time, thus forms a number of nucleation points and uniform distribution of RE is observed.

Keywords: Spark plasma sintering, 2024 AA, Rare Earth, Microstructure characterization, Mechanical properties.