In order to investigate the effect of boron additions in the magnetostrictive behavior of Fe₇₂Ga₂₈ alloy, this alloy was doped with 0.5, 1.0, 1.5 and 2.0 at.% of boron. The results have shown that boron additions of 0.5 and 1.0% improve significantly the magnetostriction, the values being about two-fold higher compared to the undoped alloy. Microstructural evaluations suggest that boron additions suppress partially the D0₃ phase ordering, retaining the α-phase. Furthermore, the increase of lattice parameters of the α and D0₃ phases indicates that boron enters interstitially in the cubic lattice of these phases. Both effects are considered to be responsible for the increased magnetostriction observed in the (Fe_0.72Ga_0.28)_99.5B_0.5 and Fe_0.72Ga_0.28)_99.0B_1.0 alloys.

Additive manufacturing (AM) is revolutionizing the fabrication of metallic components, offering significant potential to compete with or complement traditional casting, forging, and machining processes, and enabling the production of complex functional components. Recent advancements in AM technology have facilitated the processing of shape memory alloys (SMAs) with functional properties comparable to those of conventionally processed alloys. However, the AM of NiTi SMAs remains underexplored due to the extreme complexity of the process, high melting point, and reactivity with oxygen. This study investigates the impact of AM processing on the shape memory properties of NiTi alloys using the Micro Wire and Arc Directed Energy Deposition (μ-WA-DED) technique in short circuit mode with a pioneering 0.3 mm pre-alloyed wire, focusing on increasing precision and control in the deposition process. The macroscopic morphology, microstructure, phase composition, phase-transformation temperatures, and mechanical properties of each deposited layer were analyzed. Results indicated austenite (B2) as the predominant phase, with retained martensite (B19′) and a reversible martensitic transformation (B2 ⇌ B19′) in the second layer. Mechanical characterization revealed variations in hardness (H) and elastic modulus (E) due to microstructural heterogeneity and composition. The first layer exhibited H = 3.8 GPa and E = 70 GPa, associated with the B2-NiTi phase, while higher values were obtained in the second layer, i.e., E = 100 GPa and H = 7 GPa. This study establishes for the first time the feasibility of NiTi alloy deposition with a 0.3 mm wire, setting a new standard for future research and applications in AM using μ-WA-DED.