On the effects of selective laser melting process parameters on microstructure and thermomechanical response of Ni-rich NiTi

Laser Powder Bed Fusion of Ti-rich TiNi lattice structures: Process optimisation, geometrical integrity, and phase transformations

“…As shown in Fig. 5, the formation of irregular pores was attributed to the turbulence in the melt pool at high P or E v , or insufficient heat input leading to lack of fusion defects [14,36].…”

“…5. The morphology of the sample produced using 44 J/mm 3 showed irregular pores with unconsolidated particles, which is characteristic of lack of fusion defects caused by insufficient heat input [14]. At E v of 267 J/mm 3 , the sample exhibited a significant number of spherical pores, which is characteristic of keyhole defects [32,33].…”

“…However, LPBF of TiNi encounters a number of challenges, including the formation of structural defects (pores, cracks, or lack of fusion), selective Ni-evaporation, pick-up of impurity elements, and the formation of intermetallic particles, which affect the phase transformation temperatures, mechanical behaviour and functional properties [5,12,14].…”

Laser beam energy dependence of martensitic transformation in SLM fabricated NiTi shape memory alloy

“…Relevant researches on the selective laser melting (SLM) fabricated NiTi alloy are mainly concentrated on the processing optimization with both pre-alloying powder [6][7][8][9][10][11][12][13][14][15][16][17][18] and mixed pure powders [19] as starting powder materials, the measurement of martensitic transformation temperatures [6][7][8][9][10][11][12][13][14][15][16][17][18], the detection of the stress or strain-induced martensitic transformation from different thermomechanical conditions [10,12,15,[16][17][18], the effect of post-heat treatment [10,12], evaluation of other functional properties such as the damping properties [6] and the fatigue behavior [13,14]. Based on these numerous investigations, it is worth noting that it exists large discrepancies in results, especially in terms of the final mechanical properties and shape memory effects.…”

“…As the origin of functional properties of NiTi alloy, the MT indeed plays a crucial role in the final processing and optimization. That is why the MT temperatures [6][7][8][9][10][11][12][13][14][15][16][17][18] and the critical stress inducing the martensitic transformation [10,12,15,[16][17][18] are widely investigated by most of…”