## 1 Introduction  
Among Shape Memory Alloys (SMAs), intermetallic near equiatomic NiTi compound is the most diffused and well-known smart metallic material, which can offer unique properties, among which the more characteristic are shape memory effect (SME) and pseudoelasticity (PE) [1]. These peculiar characteristics depend on a diffusionless phase transformation occurring in the solid state, namely martensitic transformation (MT), which occurs, to a first approximation, above room temperature in Ti-rich NiTi, and below room temperature in Ni-rich NiTi alloys [2]. Transformation temperatures of the MT and stable, functional characteristics are strongly affected not only by Ni/Ti ratio but also by microstructural features such as grain size, texture, and eventual secondary phases or precipitates. All these features are intimately related to the thermal history of the material during production: this correlation imposes a strict control of the manufacturing parameters for fixing the final functional performances of NiTi SMA parts [3, 4]. In the last years, the most studied advanced manufacturing process of NiTi SMA has been 3D printing, or additive manufacturing (AM), which is able to offer flexibility in designing complex structures integrating the functional performances of this smart material [5; 6; 7]. Literature reports several scientific works regarding significant issues to be taken into account, including Ni loss [8], suitable heat treatments [9], and functional performance optimization of the parts [10]. The most diffused and investigated AM process is the Laser Powder Bed Fusion (LPBF) or Selective Laser Melting (SLM). Other relatively new metal additive manufacturing methods, such as Wire Arc Additive Manufacturing (WAAM) process, have the advantage of higher deposition rates and the capability of producing larger components but suffer from lower accuracy [11; 12; 13]. Thus, LPBF or SLM can offer much superior accuracy and greater flexibility in geometry design. In this process, a high-power laser beam melts a portion of the powder bed locally: this indicates very high cooling rates can be achieved, provoking the generation of fine and oriented grains. Anyways, due to high thermal gradients induced by the laser beam scans, some local chemical inhomogeneities can also be another typical issue of the SLM process. The literature provides several works focused on processability, microstructure, and functional properties of additive manufactured samples produced using Ni-rich NiTi and Ti-rich NiTi powders, specifically for biomedical and aerospace applications. A common finding is that MT temperatures comparable to those of the wrought alloy can be obtained [1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15]; at the same time, the modulation of MT through a strict Ni/Ti ratio control reveals to be a challenging issue [16; 17]. SLMed and wrought NiTi also differ in other relevant issues: different texture orientations are generally observed, and local chemical compositions which arise from the manufacturing process characteristics, such as cooling rates and thermal gradients [18], proved to be critical for the former. The NiTi-built microstructure can be strongly textured due to the evident epitaxial grain growth, oriented along the building direction [19]. The obtained microstructure is able to tailor the functional properties, as reported in several works [20; 21; 22]. The usable incident laser fluence range can induce different cooling rates and modified melt pool sizes, which are able to induce the formation of microstructures exhibiting different levels of texturing. Indeed, most of the reported literature works make use of lasers working in continuous mode, limited laser fluence variation is considered, and comparison of works from different research groups can be difficult due to variated initial powder composition of ancillary production conditions.