Thermal-driven gigantic enhancement in critical current density of high-entropy alloy superconductors

•Annealing effects on the superconducting critical properties of Ta1/6Nb2/6Hf1/6Zr1/6Ti1/6 high-entropy alloy (HEA) superconductors are systematically studied.•The zero-field Jc at 4.2 K for the annealed sample at 550 °C for 24 h is increased significantly by approximately 1,860 % compared to the as-cast sample.•In annealed HEA superconductors, normal point pinning becomes dominant.•Vickers hardness is significantly improved from ∼384 to 528 HVIT through thermal annealing.