Microstructure and strengthening mechanisms in FCC-structured single-phase TiC–CoCrFeCuNiAl0.3 HEACs with deformation twinning

This study aimed to investigate dislocation structures in CuNiCoFeCrAl0.3 alloy particles using a transmission electron microscope (TEM). A non-equiatomic CoCrFeCuNiAl0.3 high-entropy alloy composite (HEAC) reinforced with TiC5vol% nanoparticles was produced by mechanical alloying and spark plasma sintering. X-ray and TEM microanalyses confirmed the predominance of a nanotwinned single-phase face-centered cubic (FCC) solid solution with TiC nanoparticles. Further findings revealed that twin structure formation in FCC high-entropy alloys (HEAs) by the powder metallurgy technology was dependent on dislocations and the stratified structure formed in particles during mechanical alloying, low stacking-fault energy γSF, pressure, and hardness phase. The TiC5vol%–CoCrFeCuNiAl0.3 HEAC had the following excellent comprehensive mechanical properties: yield strength, 1582 MPa; fracture strength, 2185 MPa; and plastic strain, 23.60%. The dislocation glide and semi-twin expansion in HEAs provided excellent plasticity, while TiC particles and transgranular twins contributed to the material strength.