Microstructure and properties of a shape memory alloy Ti–Ni–Al–V fabricated by double-wire arc additive manufacturing

Abstract

In this study, a novel heterogeneous double-wire arc additive manufacturing method was used for the in-situ synthesis of a novel Ti–Ni–Al–V alloy wall. The results indicated that the synthesis wall was composed of the NiTi2, B2, and Ni4Ti3 phases from the bottom to the top. With an increase in deposition layers, the Ti2Ni content decreased. The hardness at the bottom was ∼685.4 HV0.2, while that of the middle and stable regions was 553 HV0.2. The maximum compressive strength was 2100 MPa. The fracture morphology was brittle. After cyclic compression, the recoverable and unrecoverable strains were 4.79 % and 1.21 %, respectively, indicating excellent recovery characteristics. Highlights: • A novel Ti–Ni–Al–V alloy fabricated in situ for the first time • Reaction between pure Ni and Ti–6Al–4V wires occurs in weld pool • As-Built wall is composed of NiTi2, B2, and Ni4Ti3 phases • Microhardness of Ti–Ni–Al–V alloy stabilized at 553 HV0.2.

Keywords

• Shape memory materials
• Metals and alloys
• Ti–Ni–Al–V alloy
• Microstructure