Surface energies and size-effects in shape-memory-alloys

A model for martensitic microstructure, its geometry and interface effects

“…Minimization of the elastic energy alone bears no implication of accommodation and the length scale properties observed. This suggests the presence of other constituents of energy with comparable orders of magnitude [1,3], namely the twin interfacial energy and the grain boundary energy. For the grain boundary energy we follow our derivation in [5], taking the energy density…”

Partially relaxed energy potentials for the modelling of microstructures – application to shape memory alloys

“…On the other hand, the interfacial energy between α and β, which in the general case can additionally be considered in ψ, increases with smaller values of l so that l must take finite values. This will lead to enhanced lamination theories as, for example, discussed in [22][23][24][25]. Here and in the following, we solve this problem simply by assuming that interfacial energies among the phases are negligible.…”

Theoretical Prediction on Martensitic Transformation Start-Strain of Nitinol

“…Following the micromechanical model proposed in our recent papers [8][9][10][11] we consider a representative volume element (RVE) of Nitinol polycrystal which is composed of many (say N-1) possible martensite variants (MVs). When N is large enough, the RVE may consist of grains.…”

“…Then following similar steps suggested in literature, [8][9][10][11] after substituting eq. (9) with eqs.…”

“…[8][9][10][11]). Starting with the observation of the MT, this framework successfully predicted various aspects of the microstructure evolution process and consequently the macroscopic properties such as shape memory effect, superelasticity, martensite reorientation mechanism and asymmetry of tension/compression response (detail, see Refs.…”