Optimization of Post-processing Annealing Conditions of the Laser Powder Bed-Fused Ti-18Zr-14Nb Shape Memory Alloy: Structure and Functional Properties

摘要

Ti-18Zr-14Nb (at%) shape memory alloy was processed by laser powder bed fusion (LPBF) and subjected to post-processing annealing treatments in the 500-800°C temperature range. The microstructure, crystallographic texture, static mechanical properties, and low-cycle fatigue behavior of this alloy in the as-built state and after different post-fusion annealings have been studied. It was found that a strongly columnar microstructure developed during LPBF processing morphed into a predominantly equiaxed grain structure after 800°C recrystallization annealing. However, the highest number of cycles to failure during high-intensity strain-controlled fatigue testing (2% of strain in a cycle) was obtained after annealing at 500°C, whereas the lowest number of cycles was found after annealing at 700°C. A beneficial combination of static and fatigue mechanical properties with a relatively low Young's modulus makes 500°C-annealed LPBF Ti-18Zr-14Nb components suitable for biomedical applications, especially where the capacity of LPBF to manufacture geometrically complex and patient-specific load-bearing components makes a difference.