Effect of low-temperature precipitates on microstructure and pseudoelasticity of an Fe–Mn–Si-based shape memory alloy

Effect of Cerium Addition on the Microstructure and Shape Memory Properties of Austenitic Fe–Mn–Si–Cr–Ni Alloys

“…Recent studies have shown that precipitates can facilitate the formation of numerous SFs in austenitic phase. [37] This phenomenon occurs due to dislocation dissociation at the matrixprecipitate interface, which adjusts the elastic strain field. [38,39] As a result, the newly formed dislocations may experience a decrease in the local SFE in the presence of Ce-rich particles with high Si content, leading to a reduction in the overall SFE of the alloys with Ce addition.…”

“…[38,39] As a result, the newly formed dislocations may experience a decrease in the local SFE in the presence of Ce-rich particles with high Si content, leading to a reduction in the overall SFE of the alloys with Ce addition. Khodaverd et al [37] suggested that the change in the local chemical composition of the austenite surrounding the precipitates and the lattice strain during their formation may play a key role in the formation of the SF and the increase in the M S temperature.…”

“…In these alloys, monovariant ε-martensite plates were formed within austenitic grains, which could be due to the formation of Ce-rich particles. It has been suggested [37] that precipitates promote the formation of SFs grouped along the same orientation within austenitic grains instead of randomly oriented SFs, which favors the formation of monovariant ε-martensite plates. Although the formation of monovariant ε-martensite plates in combination with the strengthening of the austenitic phase with 0.42 wt% Ce and a lower SFE of 12 mJ m À2 is considered the ideal approach to achieve better SME, [8,44,46] the stress-induced martensite volume fraction was half that observed for SMA-1 (about 20%).…”

Memory‐Steel for Smart Steel Structures: A Review on Recent Developments and Applications

“…Furthermore, studies by Khodaverdi et al [13] indicate low-temperature aging at 485 °C in combination with high-temperature precipitates further enhances the PE of the alloy. The formation of sigma-type precipitates aligns stacking faults within the austenite grains (Figure 3), which improves the martensitic phase transformation and reduces the formation of undesired martensite phases [13]. Overall, these findings provide insights into improving the PE behaviour of Fe-SMAs, making them a promising alternative to NiTi-SMAs for seismic applications.…”

Verstärkung von Stahlkonstruktionen mit Memory‐Stahl

“…Bei weniger steifen Bauteilen kann die Vorspannung reduziert werden.Abschließend wird eine externe Last auf das verstärkte Bauteil aufgebracht (Bild 1c.v). Das führt zu einem Anstieg der Spannung im Fe-SMA (Bilder 1a, 1b -Pfad 5).Darüber hinaus zeigen Untersuchungen von Khodaverdi et al[35], dass eine Niedrigtemperaturalterung bei 485 °C in Kombination mit Hochtemperaturausscheidungen die PE der Legierung weiter optimieren kann. Die Bildung von Sigmaausscheidungen richtet Stapelfehler innerhalb der Austenitkörner aus (Bild 4), was die martensitische Phasenumwandlung verbessert und die Bildung unerwünschter Martensitphasen verringert[35].Insgesamt bieten diese Ergebnisse Einblicke in die Verbesserung des PE-Verhaltens von Fe-SMAs und machen sie zu einer vielversprechenden Alternative zu NiTi-SMAs für seismische Anwendungen.…”