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A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 0 6 7 Shape Memory and Super- elasticity: Advances in Science and Technology ( SMJ ) is the offi- cial journal of the International Organization on Shape Memory and Superelastic Technologies (SMST), an affiliate society of ASM International. The jour- nal publishes original peer- reviewed papers that focus on shape memory materials re- search with contributions from materials science, experimental and theoretical mechanics, physics with cognizance of the chemistry, underlying phases, and crystallography. It also provides a forum for researchers, scientists, and engineers of varied disciplines to access information about shape memory materials. The first two articles were taken froma special issue containing articles from the SMST 2019 Conference, published inDecember 2019. The next two are fromtheMarch 2020 issue, which featured papers from the International Conference on Ferromagnetic Shape Memory Alloys (ICFSMA) 2019. All were selected by Shape Memory Editor-in-Chief Huseyin Sehitoglu SMJ is available through springerlink.com . For more informa- tion, visit asminternational.org/web/smst. B2  ⇒  B19' ⇒  B2 T MARTENSITIC TRANSFORMATION AS A MECHANISM OF PLASTIC DEFORMATION OF NiTi P. Ŝittner, L. Heller, P. Sedlák, Y. Chen, O. Tye, OMolnárová, L. Kadeřávek, and H. Heiner Deformation of superelastic NiTi wire with tailored mi- crostructure was investigated in tensile loading–unloading tests up to the end of the stress plateau in wide temperature range from room temperature up to 200°C. Lattice defects left in the microstructure of deformed wires were investigated by transmission electron microscopy. Tensile deformation is localizedup to thehighest test temperatures, even if practically no martensite phase exists in the wire at the end of the stress plateau. In tensile tests at elevated temperatures around 100°C, at which the upper plateau stress approaches the yield stress for plastic deformation of martensite, upper plateau strains become unusually long, transformation strains be- come unrecoverable and deformation bands containing aus- tenite twins appear in the microstructure of deformed wires. These observations were rationalized by assuming activity of B2  ⇒  B19′  ⇒  B2 T martensitic transformation into the austenite twins representing a newmechanismof plastic deformation of NiTi, additional to the dislocation slip in austenite and/or mar- tensite. It is claimed that this transformation becomes activat- ed in any thermomechanical load in which the oriented B19′ martensite is exposed to high stress at high temperatures, as e.g., during shape setting or actuator cycling at high applied stress (Fig. 1). THE ROLE OF PARENT PHASE COMPLIANCE ON THE FATIGUE LIFETIME OF NiTi C. Bonsignore, A. Shamini, and T. Duerig It has been previously suggested that the fatigue lifetime of superelastic Ni–Ti might be improved if the R-phase were the parent to martensite rather than austenite. This body of work tests that hypothesis in two separate side-by-side fatigue tests both carefully constructed to match the superelastic properties in the two study arms. Both experiments show the R-phase parent to be more durable than the more common- ly considered austenitic parent phase. The first experiment considers straight wire specimens fabricated from standard purity material, in a tension–tension fatigue test to 107 cycles, at mean strain ranging of 0.5–5.8% and strain amplitudes of 0.15–0.45%. The second experiment considers formed wire specimens in bending fatigue, more representative of realistic Fig. 1 — Tensile tests on 16 ms NiTi wire at various test temperatures till rupture: (a) stress–strain curves; (b) material parameters evaluated from tensile tests: upper plateau stress σ UP , yield stress σ ν and upper plateau strain σ p UP are determined from the stress–strain curves in (a). 1 3 SMJ HIGHLIGHTS