Most research to date in the field of L-PBF of nitinol has been with near equiatomic nickel-titanium binary pre-alloyed powders. Significant understanding over the last 10 years has been gained in relation to aspects such as microstructural evolution, control of elemental composition, phase transformation behaviour, control of defects and mechanical properties. Challenges with the use of pre-alloyed nitinol powders include expense and time constraints in producing new blends. Elemental blending with in-situ alloying of nickel, titanium and other constituents at the point of additive manufacture offers the opportunity to significantly accelerate the pace of research of nitinol material and part geometry design. Other potential advantages of elementally blended over pre-alloyed powders include reduced process costs, energy savings, and improved control over final part macroscopic properties as well as local microscopic composition and properties. The relationship between elemental and pre-alloyed powder characteristics, the nitinol L-PBF process parameters and the resulting melt homogeneity has not previously been examined. This paper addresses this gap by examining, for in-situ alloyed nitinol, the relationship between laser power, scanning speed, powder properties and the resulting solidification track characteristics, and comparing results to those from pre-alloyed powder.

Due to the unique characteristics of nitinol (NiTi) such as shape memory and super-elasticity, it is widely utilized in various industries, particularly in aerospace and biomedical applications. Additive manufacturing technology can provide the accurate dimensioning of NiTi components, even for those with intricate and complex geometries. However, the presence of residual stresses poses a significant concern from additive manufacturing. These residual stresses can adversely impact the structural integrity and performance of the manufactured parts, necessitating careful consideration and management. This study delves into a distinctive approach for predicting residual stresses within additive manufactured NiTi components, employing a simple, non-destructive, and cost-efficient method that integrates beam mechanics equations with finite element analysis (FEA). This work aimed to develop a rapid and accurate method for measuring the residual stress from additively manufactured nitinol beams which will be validated via established techniques such as hole-drilling, XRD and/or neutron diffraction.

Nickel-titanium offers a promising alternative to traditional actuation devices due to its shape memory effect (SME) large strain recovery, and damping capability. Shape memory alloy actuators, thereby, offer a low-shock alternative to traditional pyrotechnic release devices used in spacecraft and satellites as well as energy-absorption components such as spacecraft landing systems. Additive manufacturing (AM) allows the production of complex geometries benefiting from their lightweight and compact nature. A prime example is lattice structures, with a geometrically defined porous structures featuring a repeating unit cell pattern or patterns in space. Beyond being lightweight, these structures offer high specific strength, excellent shock absorption, heat dissipation, and biocompatibility. By examining different process parameters, AM presents the possibility of tailoring nitinol’s properties while potentially removing the additional step of post-processing heat treatments conventionally required for shaping shape memory alloys. This approach has the potential to save time, cost, and energy.