Compression and superelasticity behaviors of NiTi porous structures with tiny strut fabricated by selective laser melting

Abstract

Though NiTi alloys are widely utilized in biomedical and automotive industries, conventional processing methods can hardly fabricate porous NiTi alloys. Selective laser melting shows prominent advantages in fabricating complex structure with relatively high surface finish and geometrical accuracy. In the present paper, we investigated the compression and superelasticity behaviors of selective laser melting fabricated NiTi porous structures with tiny strut (0.6 mm, 0.4 mm and 0.2 mm). When the strut thickness decreased from 0.6 mm to 0.2 mm, the compressive strain of the NiTi structure firstly decreased and then increased, the best compressive strain (28%) was obtained when the strut thickness was 0.4 mm and the scanning speed was 400 mm/s. The recovery strain increased monotonously as the strut thickness decreased, the best recovery strain (10%) was obtained when the strut thickness was 0.2 mm and the scanning speed was 200 mm/s. The compressive strain was closely related to both the martensitic transformation temperature and the defect volume fraction, while the recovery strain was mainly affected by the martensitic transformation temperature.