Microstructure, mechanical properties and energetic characteristics of a novel high-entropy alloy HfZrTiTa0.53

A novel HfZrTiTa0.53 high-entropy alloy (HEA) was fabricated by arc vacuum melting. The microstructure, mechanical behavior loaded at the initial strain rates from 1.0 x 10(-3) to 2.2 x 10(3) s(-1) and energetic characteristics were studied. Results reveal that the alloy is composed of two phases with the same body-centered cubic (BCC) structure and similar lattice constant. Dispersed nano lamellar modulated structure inside equiaxed grain is derived from spinodal decomposition. Due to the co-contribution of solid solution strengthening and spinodal decomposition hardening, the quasi-static yield strength, compressive strength and fracture strain of HfZrTiTa0.53 alloy reach 786 MPa, 1314 MPa and 13.5%, respectively. Strain rate strengthening effect is clearly observed in this alloy. In the dynamic regime, the alloy displays thermoplastic instability and deformation is strong localized in adiabatic shear bands and co-influenced by strain hardening, strain rate strengthening and thermal softening. Upon high-speed impact, the HfZrTiTa0.53 energetic projectiles were initiated and reacted with air to release a large quantity of energy. Excellent mechanical properties and high density, along with good energetic characteristics contribute to structural reliability, good penetrating performance and high energy release of HfZrTiTa0.53 HEA, demonstrating its great potential to be high strength energetic structural materials. (C) 2017 Elsevier Ltd. All rights reserved.