• Schell, Norbert
• Moura, Isaque A. B.
• Wang, Binbin
• Shen, Jiajia
• Ghafoori, Elyas
• Barragan, André F. C.
• Oliveira Felice, Igor
• Khodaverdi, Hesamodin
• Santos, Telmo G.
• Li, Binqiang
• Oliveira, João Pedro
• Mohri, Maryam

Abstract

<p>Shape memory alloys (SMA) are a class of smart materials with inherent shape memory and superelastic characteristics. Unlike other SMAs, iron-based SMAs (Fe-SMA) offer cost-effectiveness, weldability, and robust mechanical strength for the construction industry. Thus, applying these promising materials to advanced manufacturing processes is of considerable industrial and academic relevance. This study aims to present a pioneer application of a Fe–Mn–Si–Cr–Ni–V-C SMA to arc-based directed energy deposition additive manufacturing, namely wire and arc additive manufacturing (WAAM), examining the microstructure evolution and mechanical/functional response. The WAAM-fabricated Fe-SMAs presented negligible porosity and high deposition efficiency. Microstructure characterization encompassing electron microscopy and high energy synchrotron X-ray diffraction revealed that the as-deposited material is primarily composed by γ FCC phase with modest amounts of VC, ε and σ phases. Tensile and cyclic testing highlighted the Fe-SMA's excellent mechanical and functional response. Tensile testing revealed a yield strength and fracture stress of 472 and 821 MPa, respectively, with a fracture strain of 26%. After uniaxial tensile loading to fracture, the γ → ε phase transformation was clearly evidenced with post-mortem synchrotron X-ray diffraction analysis. The cyclic stability during 100 load/unloading cycles was also evaluated, showcasing the potential applicability of the fabricated material for structural applications.</p>

Topics

• Deposition
• impedance spectroscopy
• phase
• x-ray diffraction
• strength
• electron microscopy
• iron
• yield strength
• porosity
• wire
• directed energy deposition