Effect of carbon nanotubes on microstructure and mechanical properties of TiZrVMnCu–Er high entropy alloy composites

Abstract To improve the ductility and toughness of refractory high entropy alloy (Ti, Zr, V), Mn and Cu were added to form TiZrVMnCu high entropy alloy with soft and hard phases. Carbon nanotubes (CNTs) and Er were introduced to fabricated composites with high strength and ductility. The relative density, microhardness, and compressive strength of TiZrVMnCu–Er–CNTs composites were in direct proportional to CNTs content from 0 to 0.5 wt%. The composite with 0.5 wt% CNTs has the highest hardness (634.4 HV) and strength (1720.7 MPa), and the strain variable is 14.3 %. The fracture toughness of the composites was improved by the crack bridging mechanism and crack deflection mechanism induced by adding CNTs. The fine grain, second phase strengthening mechanism, and the load transfer mechanism induced by CNTs improved the strength and hardness of the composites. Er can achieve solid solution strengthening or play a role in the second phase and fine grain strengthening.