ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2026 38 SMJ HIGHLIGHTS Shape Memory and Superelasticity: Advances in Science and Technology (SMJ) is the official journal of the International Organization on Shape Memory and Superelastic Technologies (SMST), an affiliate society of ASM International. The journal publishes original peer-reviewed papers that focus on shape memory materials research 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. Both articles were taken from the June 2026 issue. They were selected by Shape Memory Editor-in-Chief Huseyin Sehitoglu. SMJ is available through link.springer.com. For more information, visit asminter- national.org/smst. June 2026 VERY HIGH CYCLE FATIGUE OF WROUGHT NiTi SHAPE MEMORY ALLOYS Pete Angelo Rocco, Alireza Behvar, Harsh Kamlash Bajaj, Meysam Haghshenas, and Mohammad Elahinia Very-high-cycle fatigue (VHCF) data for superelastic NiTi beyond 107 cycles remain limited, particularly for wrought, precipitate-tuned conditions tested under ultrasonic loading. Here, the VHCF response of a Ni-rich wrought NiTi (Ni50.8Ti49.2) was quantified by coupling calorimetry and monotonic mechanics with 20 kHz axial ultrasonic fatigue in fully reversed loading (R = -1) using pulse-pause control and forced-air cooling to mitigate self-heating. The alloy was solutionized at 1000°C for 2 h and aged at 600°C for 1 h to promote Ni4Ti3 precipitation. DSC showed suppressed transformation temperatures relative to the non-heat-treated state, with a two-step B2 → R → B19′ sequence on cooling and a sharp reverse transformation on heating (Af = 9 to 10°C). Room-temperature tensile tests confirmed a fully austenitic starting state (E=61.9 GPa) and a stress-induced martensitic transformation (SIMT) onset near 223 MPa with a 250 to 300 MPa transformation plateau. S–N data spanning 105 to 109 cycles were fitted by a Basquin relation (σf’ = 653.7 MPa, b = -0.089), indicating a gradual fatigue-strength reduction with increasing life and increased scatter in the VHCF regime without a clear endurance limit. Fractography and EDS revealed a stress-dependent transition in crack initiation: higher-amplitude failures were dominated by surface slip/ damage, whereas VHCF failures initiated subsurface at Ti-rich nonmetallic inclusions (TiC and Ti2NiOx). These results provide a benchmark VHCF dataset for wrought NiTi under R = -1 ultrasonic loading and clarify how precipitation-tuned transformation behavior and inclusion populations govern VHCF crack initiation (Fig. 1). Fig. 1 — Schematic representation of the experimental procedure implemented in this study, illustrating the steps involved in sample preparation, fatigue testing, and subsequent microstructural analysis.
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