Phase Evolution and Thermal Analysis of Nanocrystalline AlCrCuFeNiZn High Entropy Alloy Produced by Mechanical Alloying

• Published in: Journal of materials engineering and performance 2013-10, Vol.22 (10), p.3077-3084
• Main Authors: Koundinya, N. T. B. N., Sajith Babu, C., Sivaprasad, K., Susila, P., Kishore Babu, N., Baburao, J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Cross-disciplinary physics: materials science; rheology; Engineering Design; Exact sciences and technology; Materials Science; Metals. Metallurgy; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Physics; Powder metallurgy. Composite materials; Production techniques; Quality Control; Reliability; Safety and Risk; Technology; Tribology
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-013-0580-5

A multi-component nanocrystalline AlCrCuFeNiZn high entropy alloy with 12 nm crystallite size was successfully synthesized using high energy ball milling. The progress of solid solution formation during milling was analyzed using XRD. A major portion of the HEA is observed to be BCC in crystal structure after 30 h of milling. Thermal analysis showed that HEA powders exhibited exponential oxidation characteristics. Thermal analysis showed that low activation energy was sufficient to start recrystallization because of high energy stored in the milled powders. The crystallite size after consolidation is in nanocrystalline range due to the sluggish diffusion of atoms and nanotwinning. After consolidation, the crystallite size is around 79 nm. Samples sintered at 850 °C for 2 h exhibited high hardness values of 700 ± 15 HV 1.0 , major volume fraction of the phases are having FCC crystal structure along with a minor phase having BCC crystal structure. Due to positive enthalpy mixing of Cu with other elements, decomposition of BCC to new FCC phases occurs.