Fabrication of Integrated Ni-Ti Alloys Possessing Both Super-elastic and Shape Memory Properties by Laser Powder Bed Fusion

Purpose: Integrated Ni-Ti alloys possessing both super-elastic (SE) properties and shape memory effects (SMEs) greatly increase the flexibility of designing complex systems and have broad application prospects. However, existing research mainly focuses on connecting ready-made SE parts and SME parts though welding. Method: In this paper, laser powder bed fusion (LPBF) was used to fabricate integrated Ni-Ti alloys. First, SE parts with high relative density were fabricated with a Ni-rich powder. Then, different process parameters were used to fabricate the SME parts with a Ti-rich powder based on the SE parts. The integrated component with the best mechanical properties herein was selected. Metallographic analysis, energy dispersive X-ray spectroscopy, differential scanning calorimetry and micro-hardness analyses were carried out for this sample. Findings: The results show that the integrated component possessed both SE and SME properties at room temperature. Moreover, at the junction of the two materials, the grains were continuous and complete, which indicates that the joint had good quality. Originality: Our work confirms that LPBF is a feasible method to fabricate integrated Ni-Ti alloys possessing both SE and SME properties.