Improvement in corrosion resistance of biocompatible Ti1.5Al0.3ZrNb refractory high entropy alloy in simulated body fluid by nanosecond laser shock processing

Abstract

A biocompatible Ti1.5Al0.3ZrNb refractory high-entropy alloy (RHEA) with high specific strength and superior tensile ductility is developed. The activation of multiple slip systems and dislocations cross-slip facilitate dislocation interactions, improving the plastic deformability and continuous strain hardening ability of the Ti1.5Al0.3ZrNb RHEA. After laser shock processing (LSP), the surface roughness of the RHEA increases and significant grain refinement occurs on the surface, from micron-grains to nano-grains. Meanwhile, abundant dislocations and dislocation debris are generated. This surface morphology significantly improves the corrosion resistance of the RHEA in simulated body fluid. The corrosion current density of the LSP-Ti1.5Al0.3ZrNb is only ∼1/3 of the Ti1.5Al0.3ZrNb, and the resistance Rct is 2.29 × 105 Ω·cm2 in the LSP-Ti1.5Al0.3ZrNb, which is an order of magnitude higher than that of the Ti1.5Al0.3ZrNb. The improved corrosion resistance of LSP-Ti1.5Al0.3ZrNb is ascribed to multiple LSP-induced compressive residual stress, grain refinement and high-density dislocations. Combining the RHEAs with LSP techniques could offer the opportunity to break existing corrosion limitation, and obtain substantial performance improvement.