Microstructure and Mechanical Properties of NiTi Alloy Prepared by Double-Wire + Arc Additive Manufacturing Plus In Situ Heat Treatment

3D Print Addit Manuf. 2024 Jun 18;11(3):1008-1015. doi: 10.1089/3dp.2023.0003. eCollection 2024 Jun.

ABSTRACT

In this study, NiTi shape memory alloy was prepared by double-wire + arc additive manufacturing plus in situ heat treatment using TA1 and ER-Ni welding wires as the raw materials. The results show that the microstructural evolution from the bottom to top is NiTi₂ + NiTi → NiTi + Ni₃Ti + Ni₄Ti₃ → NiTi + Ni₄Ti₃ + Ni₃Ti₂ + Ni₃Ti + α-Ti. Complex thermal cycles led to the precipitation of Ni₃Ti, which improves the hardness of the matrix (B2), and the average hardness value of the top region reaches 550.7 HV_0.2. The fracture stress is 2075 ± 138.4 MPa and the fracture strain is 11.2 ± 1.27%. The sample shows 7.02% residual strain and 5.87% reversible strain after 15 cycles, and the stress hysteresis decreases with an increase in cyclic strain.

PMID:39359590 | PMC:PMC11442353 | DOI:10.1089/3dp.2023.0003