Microstructure and Mechanical Properties of NiTi<sub>2</sub>-TiB Composite Fabricated by Spark Plasma Sintering

Abstract

Composites of NiTi2-TiB have been fabricated using spark plasma sintering and mechanical properties have been investigated. Dense specimens of monolithic NiTi2 have been obtained by the sintering at 950˚C. By the x-ray diffraction measurements it has been shown that NiTi2 co-exists with TiB in equilibrium at 950˚C. The bending strength of NiTi2-TiB composite increases with increasing the volume fraction of TiB2 up to 60 vol%. The maximum bending strength of 730 MPa has been obtained for NiTi2-60vol% TiB2. The Vickers hardness also increases with increasing the volume fraction of TiB up to 70% and the highest Vickers hardness of 1620 Hv has been obtained for NiTi2-70%TiB.

Searching New Solutions for NiTi Sensors through Indirect Additive Manufacturing

“…Hardness values are higher than the hardness of bulk NiTi (NiTi (B2) 275 HV, N (B19) 112 HV, NiTi2 163 HV and Ni3Ti 1071 HV [34][35][36][37]), confirming the presence of h phases (i.e., Ni3Ti) (Table 10). The hardness values are similar to those of NiTi 3D obje obtained from other non-conventional technologies (800 HV [38], 700 HV [39,40], and HV [41]). In composition C where Ni3Ti was not detected, a lower hardness was expect Indirect additive manufacturing, such as MEX, could be the sustainable technology ideal for applications where the geometry envisaged could be complex, but the thickness is less than 3 to 5 mm.…”

“…Hardness values are higher than the hardness of bulk NiTi (NiTi (B2) 275 HV, NiTi (B19) 112 HV, NiTi 2 163 HV and Ni 3 Ti 1071 HV [34][35][36][37]), confirming the presence of hard phases (i.e., Ni 3 Ti) (Table 10). The hardness values are similar to those of NiTi 3D objects obtained from other non-conventional technologies (800 HV [38], 700 HV [39,40], and 742 HV [41]). In composition C where Ni 3 Ti was not detected, a lower hardness was expected.…”

In Search of the Optimal Conditions to Process Shape Memory Alloys (NiTi) Using Fused Filament Fabrication (FFF)

“…The ultramicrohardness values are higher than the hardness of NiTi (±200 HV) [ 32 , 33 , 34 ]. This is not attributed to the low load applied during the indentation (40 mN), but to the presence of other intermetallic phases, especially NiTi 2 and/or Ni 3 Ti, which can potentially increase the hardness values to 700 [ 35 , 36 ] and 742 HV [ 37 ], respectively. The elastic moduli and Vickers hardness of the Ni–Ti intermetallic compounds decrease in the following order: Ni 3 Ti > B2_NiTi > B19′_NiTi > NiTi 2 .…”