Abstract
The effects on sample size on abnormal grain growth in inexpensive FeMnAlNi shape memory alloy (SMAs) wires and rod were investigated. It was shown that repeated heat treatments between single phase (bcc) and two phase (bcc + fcc) region resulted in abnormal grains with bamboo structure both in small sized wires and large diameter rods. Microstructural features were investigated using electron backscatter diffraction (EBSD) and it was found that 0.5 mm wires possess strong [011] texture whereas, large diameter rods have random texture after grain growth heat treatments.
Highlights
Shape memory materials with superelastic properties can recover large deformations triggered by changes in stress
Cyclic heat treatments were performed in Fe-Mn-Al-Ni alloy rods and wires to promote abnormal grain growth (AGG)
Our results show that the d/D ratio of the 0.5 mm wires is ~8 and satisfies the conditions for superelasticity
Summary
Shape memory materials with superelastic properties can recover large deformations triggered by changes in stress. Since the loading and unloading paths do not coincide, a hysteresis loop occurs, which signifies energy dissipation. Due to these unique properties, superelastic SMA materials have been considered for a wide range of civil engineering applications, such as bracing systems [1, 2], connectors [3], and concreate reinforcement [4,5,6]. The damage sustained by the structure from adverse events has been decreased and crack propagation has been prevented. Current candidate for such applications is a very well-known NiTi-based alloy called ‘Nitinol’. Fe-SMAs possess an interesting meta-magnetic response where significant changes in magnetic properties occur during superelasticity
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