## 1 Introduction
In this field, wire and arc additive manufacturing (WAAM) using an electric arc as the heat source and metal wire as the feedstock has been applied to manufacture metallic components [25], and a series of related models have been developed to improve the accuracy of prepared components [26; 27; 28]. Laser-based AM using the laser as the heat source and the powder as the feedstock, and it gives better resolution and surface finish compared with WAAM [29]. Such as Selective Laser Melting (SLM) and Laser Solid Forming (LSF), also known as Laser-based Directed Energy Deposition (LDED) technology are two widely concerning technologies for preparing NiTi [22], SLM has high precision in preparing samples while LSF can build a larger sample volume, they gradually get more research because of their advantages. There are some works on the microstructure and phase transformation of NiTi or NiTiNb prepared by SLM or LSF. [PERSON] et al. [22] found that NiTi alloys prepared by LDED appeared spatially varying composition. [PERSON] et al. [30] studied the distribution of precipitates in NiTi alloy prepared by LDED, they reported that the area fraction and size of Ni4 Ti3 precipitates decreased as the z-height (building height) increased. The above research showed that the microstructure of the samples prepared by LDED changes with the building height, so we can speculate that the sample properties will also change with the building height. [PERSON] et al. [31] found that controlling the scanning speed can regulate the transformation temperature and controlling the laser power and scanning path can regulate the microstructure, that is, the shape and arrangement of grains and the grain size. [PERSON] et al. [32] found that NiTi alloy parts prepared by combining high laser power with high scanning speed or combining low laser power with low scanning speed often have high density. The above research mainly explained the relationship between the process parameters and the microstructure and phase transformation of the prepared samples. Recently, [PERSON] et al. [33] explored the microstructure and phase transformation temperature of NiTiNb prepared by SLM, which provided a reference for us to prepare NiTiNb by LSF, they found that the microstructure of SLM-NiTiNb was composed of B2-NiTi matrix, fine NiTi+\(\beta\)-Nb eutectic phase and residual un-melted Nb particles, and the phase transformation hysteresis was increased by about 40 \({}^{\circ}\)C compared with the traditional cast NiTiNb alloy. Therefore, we can use the combination of process parameters for reference and expect the influence of LSF process parameters on NiTiNb microstructure and phase transformation to a certain extent. In previous studies [11; 31; 34; 35], the input energy density is often regarded as the key factor affecting the phase transformation behavior, and the phase transformation temperature increases with the increase of the energy density [36; 37]. However, there are still some works that show that under the same energy density, there are significant differences in the phase transformation behavior of NiTi alloys [38; 39]. Due to the complexity of potential physical phenomena in the process of AM preparation, such as large temperature gradient, extremely fast solidification, and complex thermal history, and the diversity of the combination of manufacturing process parameters, the prepared samples have great variability in microstructure and mechanical properties [40]. At the same time, the large thermal gradient in the AM process may lead to the accumulation of residual stress and deformation in the specimen [41]. The selection of different process parameters in AM preparation technology will change the microstructure, phase transformation temperature, and mechanical properties of the prepared components. In addition, due to the variability and diversity of additive manufacturing parameters, an inappropriate combination of parameters will lead to delamination and cracks.