Optimization of Post-processing Annealing Conditions of the Laser Powder Bed-Fused Ti–18Zr–14Nb Shape Memory Alloy: Structure and Functional Properties
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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.
KeywordsFatigue Mechanical behavior SMA Additive manufacturing Laser powder bed fusion Ti–Zr–Nb alloy
The authors would like to express their appreciation for the financial support provided by NSERC (Natural Sciences and Engineering Research Council of Canada) and the Ministry of Education and Sciences of the Russian Federation in the framework of the Increase Competitiveness Program of NUST “MISIS” (Grant No. K4-2014-018).
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