Effect of nitrogen on mechanical properties of CoCrFeMnNi high entropy alloy at room and cryogenic temperatures

Specimens of a CoCrFeMnNi high entropy alloy with different content of nitrogen (0.5e2.0 at.%) were prepared by induction melting. Microstructure and tensile mechanical behavior of the alloys in the ascast condition were analyzed. The alloys with a low amount of N (0.5e1.0 at.%) had a single fcc phase coarse-grained microstructure. An increase in the content of N to 2.0 at.% resulted in the precipitation of a small amount (~1%) of Cr-rich M₂N nitride particles. The yield strength of the alloys increased in proportion to the percentage of nitrogen by 117 MPa/at% N at 293 K or by 316 MPa/at% N at 77 K. The observed increase in strength was attributed to solid solution hardenin