Affiliation:
1. College of Applied Technology, Shenzhen University 1 , Shenzhen 518061, China
2. College of Engineering Physics, and Shenzhen Key Laboratory of Ultraintense Laser & Advanced Material Technology, Shenzhen Technology University 2 , Shenzhen 518118, China
Abstract
Compositional tuning of refractory high-entropy alloys (HEAs) is a powerful strategy to modulate their structural stability and mechanical properties. In this study, we investigate the sound velocities, elasticity, and mechanical properties of NbxTiZrHf (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) HEAs using ultrasonic interferometry combined with Vickers hardness measurements. Notably, the metastable bcc Nb0.2TiZrHf HEAs exhibits exceptional fracture toughness, reaching up to 12.2 MPa·m1/2, which is 1.7–3.3 times higher than that of other bcc NbxTiZrHf counterparts. The mechanism for the abnormal strengthening in fracture toughness of Nb0.2TiZrHf HEAs is primarily attributed to the stress-induced bcc-to-hcp phase transition, which promotes plasticity/ductility strengthening and crack deflection. These findings provide deep insights into “metastability engineering” for designing refractory HEAs with superior fracture toughness and high strength.
Funder
Shenzhen Science and Technology Innovation Program
National Natural Science Foundation of China
Natural Science Foundation of Top Talent of Shenzhen Technology University
Runyuan Young Principle Investigator
the Key Research Platforms and Research Projects of Universities in Guangdong Province