Actuation Response of Ti-rich Nitinol Produced by Laser Powder Bed Fusion

Additive manufacturing (AM) has been shown to provide more flexible material supply chains, device design, and unique process-structure-property relationships for many alloy systems. In recent years there has been growing interest in studying AM of Nitinol alloys and how their unique shape memory properties are affected by the powder and additive processes. In this work, the actuation response of Ti-rich Nitinol test samples produced by laser powder bed fusion (LPBF) were analyzed. The material supply is characterized by analyzing the chemistry and transformation temperatures of the atomization feedstock as well as the resulting powder properties and characteristics. Desirable additive process parameters to produce a dense part with feature resolution was determined by creating an energy density curve. Dog-bone samples were printed using two different energy density additive processes. The samples were subjected to several different post print heat treatments and evaluated for their actuation response, transformation temperatures, and microstructural features.