Nickel-Titanium (NiTi) shape memory alloys continue to attract significant attention in medicine due to their superior shape memory and pseudoelastic properties, especially in the fields of cardiovascular surgery and orthodontics [1][2][3][4]. The pseudoelastic behavior stands out in dental applications: for instance, in the case of orthodontic archwires, the pseudoelastic property of NiTi makes the application of constant stress possible over large tooth displacements [1,2], which not only minimizes tissue damage during treatment [5], but also eliminates readjustment procedures -which are quite uncomfortable for the patients -required for archwires made of conventional materials, such as medical grade stainless steel [1,[6][7][8][9]. Specifically,

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Deformation temperature and manganese content dependencies of twinning activity in two types of high Mn austenitic steels were investigated upon high velocity tensile loading. It was observed that nanotwin formation within previously formed twins dominates at subzero temperatures and significantly contributes to work hardening.

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A new multiscale modeling approach is proposed to predict the contributions of dynamic strain aging (DSA) and the resulting negative strain rate sensitivity (NSRS) on the unusual strain-hardening response of Hadfield steel (HS). Mechanical response of HS was obtained from monotonic and strain rate jump experiments under uniaxial tensile loading within the 10−4 to 10−1 s−1 strain rate range. Specifically, a unique strain-hardening model was proposed that incorporates the atomic-level local instabilities imposed upon by the pinning of dislocations by diffusing carbon atoms to the classical Voce hardening. The novelty of the current approach is the computation of the shear stress contribution imposed on arrested dislocations leading to DSA at the atomic level, which is then implemented to the overall strain-hardening rule at the microscopic level. The new model not only successfully predicts the role of DSA and the resulting NSRS on the macroscopic deformation response of HS but also opens the venue for accurately predicting the deformation response of rate-sensitive metallic materials under any given loading condition.