Microstructure and Mechanical Properties of As-Cast Al-Ti Based High Entropy Alloys with Ni-Cr-Sn and Ni-Fe-Sn Alloying Elements

This study investigates the microstructure and mechanical properties of as-cast Al-Ti-Ni-based high entropy alloys (HEAs) alloyed with Cr-Sn and Fe-Sn. The alloys were produced by arc melting under an argon atmosphere without subsequent heat treatment. Microstructural analysis using optical metallography, scanning electron microscopy (SEM), and X-ray diffraction (XRD) revealed dendritic structures with interdendritic segregation. XRD results confirmed the presence of multiphase structures composed of body-centered cubic (BCC) solid solutions and intermetallic compounds. Mechanical behavior was evaluated through Vickers hardness and uniaxial compression testing, while theoretical densities calculated from alloy compositions were used to obtain specific hardness values (HV·cm³/g). Among the examined alloys, Al-Ti-Ni-Cr-Sn achieved a specific hardness of 90.21 and an ultimate compressive strength (UCS) of 1096 MPa, whereas Al-Ti-Ni-Fe-Sn recorded a specific hardness of 55.19 and a UCS of 515 MPa. Overall, the findings demonstrate that Al-Ti-Ni-based HEAs exhibit promising potential for lightweight, high-strength, and wear-resistant structural applications without the need for post-solidification processing.