NiTi alloys fabricated by laser powder bed fusion (LPBF) additive manufacturing technology not only address the compositional instability resulting from complex processes but also solve the challenges of difficult machining of intricate aerospace structures. However, there are very few reports on the wear behavior of LPBF-NiTi alloys. In the present work, the effects of microstructure and thermal treatment, including heat treatment and frictional heat, on the wear behavior of LPBF-NiTi alloy and 100Cr6 ball were analyzed through a series of tribological experiments with different sliding speeds. As the average sliding speed increases (0.079–0.216 m/s), the wear rate of the as-built and heat-treated samples tends to decrease in the range of 2.69 × 10³–0.97 × 10³mm³/m. Although the heat-treated LPBF-NiTi alloy is 46 % harder than the as-built alloy is, the latter has a higher toughness (505 MJ/m³) and greater transformation strain of SIM (0.097). This leads to a coupling effect of heat treatment and sliding speed on the wear resistance. In addition, the wear track morphologies under different sliding speeds are asymmetric due to the 24% greater acceleration at the far end from the motor and the 2.15 mm deviation between the maximum speed position and the geometric center of the track. The wear modes of the as-built and heat-treated samples included adhesive, abrasive and delamination wear. Moreover, the wear morphologies and dominant wear modes change with the frictionally caused heat release induced by the sliding speed.

Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic devices. The essential magnetic properties of Nd-Fe-B magnets, particularly coercivity and remanent magnetization, are significantly influenced by the phase characteristics and microstructure. In this work, Nd-Fe-B magnets were manufactured using vacuum induction melting (VIM), laser directed energy deposition (LDED) and laser powder bed fusion (LPBF) technologies. The microstructure evolution and phase selection of Nd-Fe-B magnets were then clarified in detail. The results indicated that the solidification velocity (V) and cooling rate (R) are key factors in the phase selection. In terms of the VIM-casting Nd-Fe-B magnet, a large volume fraction of the α-Fe soft magnetic phase (39.7 vol.%) and Nd₂Fe₁₇B_x metastable phase (34.7 vol.%) are formed due to the low R (2.3 × 10⁻¹ ℃ s⁻¹), whereas only a minor fraction of the Nd₂Fe₁₄B hard magnetic phase (5.15 vol.%) is presented. For the LDED-processed Nd-Fe-B deposit, although the Nd₂Fe₁₄B hard magnetic phase also had a low value (3.4 vol.%) as the values of V (<10⁻² m s⁻¹) and R (5.06 × 10³ ℃ s⁻¹) increased, part of the α-Fe soft magnetic phase (31.7 vol.%) is suppressed, and a higher volume of Nd₂Fe₁₇B_x metastable phases (47.5 vol.%) are formed. As a result, both the VIM-casting and LDED-processed Nd-Fe-B deposits exhibited poor magnetic properties. In contrast, employing the high values of V (>10⁻² m s⁻¹) and R (1.45 × 10⁶ ℃ s⁻¹) in the LPBF process resulted in the substantial formation of the Nd₂Fe₁₄B hard magnetic phase (55.8 vol.%) directly from the liquid, while the α-Fe soft magnetic phase and Nd₂Fe₁₇B_x metastable phase precipitation are suppressed in the LPBF-processed Nd-Fe-B magnet. Additionally, crystallographic texture analysis reveals that the LPBF-processed Nd-Fe-B magnets exhibit isotropic magnetic characteristics. Consequently, the LPBF-processed Nd-Fe-B deposit, exhibiting a coercivity of 656 kA m⁻¹, remanence of 0.79 T and maximum energy product of 71.5 kJ m⁻³, achieved an acceptable magnetic performance, comparable to other additive manufacturing processed Nd-Fe-B magnets from MQP (Nd-lean) Nd-Fe-B powder.