Microstructural evolution, mechanical properties and corrosion behaviors of in-situ TiC reinforced AlCoCrFeNi high-entropy alloys

The novel (AlCoCrFeNi) 100– x (TiC) x ( x = 0, 2, 4, 6, and 8) high-entropy alloys (HEAs) with high specific strength and excellent corrosion resistance are successfully fabricated. Microstructure analysis indicated that the AlCoCrFeNi HEA was made up of BCC and B2 phases and exhibited course equiaxed grains. After introducing Ti and C, in-situ TiC phase is formed during high-temperature reaction, and the microstructure are comprised of a mixture of BCC, B2, TiC, and σ phases. An increase of Ti and C content reduces the density and improves the strength without remarkably decrease of ductility of the alloys. As Ti and C content increases, the specific yield strength of the alloys obviously increases from 237.62 MPa·cm 3 ·g –1 to 296.26 MPa·cm 3 ·g –1 . With an increase of Ti and C content, the corrosion potential increases from –266 mV to –222 mV and the corrosion current density reduces from 1×10 –1 μA·cm –2 to 3.16×10 –2 μA·cm –2 , which can effectively improve the corrosion resistance of the alloys. This is mainly attributed to the formation of a more stable and protective passive film, which effectively inhibit the passive film breakdown. This finding also provides a new insight into the development of high-performance HEAs with high strength and excellent corrosion resistance for structural materials application.