Nearly full-density pressureless sintering of AlCoCrFeNi-based high-entropy alloy powders


AlCoCrFeNi is among the promising high-entropy alloys (HEAs) that possess high strength with considerable ductility. Powder sintering is one of the competitive routes for the production of HEA powders. However, sintering of HEA powders under a pressureless condition is difficult. The present work aims to produce high-density components from mechanically alloyed AlCoCrFeNi HEA powders through the pressureless sintering method. Nearly full density was achieved at 1275 °C. Sintering was performed in the presence of a viscous phase in the temperature range of 1200–1250 °C, which was confirmed through differential scanning calorimetry and dilatometric measurements. This viscous phase was found have a Cr-rich composition, detected by interrupting the sintering and quenching of the sample. The powder initially contained the BCC phase with a small fraction of FCC and other phases. During sintering, a significant fraction of the FCC phase and nanosized B2 phase were formed. Sintered sample had a hardness of 679 ± 20 Hv.

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Authors thank Dr. S.K. Malladi from MSME, IIT Hyderabad, for their help in TEM work.

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Correspondence to Bharat B. Panigrahi.

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Rohila, S., Mane, R.B., Ummethala, G. et al. Nearly full-density pressureless sintering of AlCoCrFeNi-based high-entropy alloy powders. Journal of Materials Research 34, 777–786 (2019).

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