Phase transformations, fracture, and other structural changes in inelastic materials

Grain boundary-induced martensitic transformations: A phase-field study of nucleation, size-effect, triple junction-effect, microstructures, and compatibility at the nanoscale

“…Nucleation was also observed due to the stress concentration within dislocation pileups near the GBs and shear bands (see, e.g. [15] and the references therein) and due to the geometric constraint within the samples in [106].…”

“…Grain boundary-induced martensitic transformations: Austenite (A)↔martensite (M) phase transformations play a central role in various industrially important materials, including shape memory alloys (SMAs) which can recover large strains and exhibit superelasticity [1][2][3][4]; dual phase steels where a proper mixture of ferrite and martensite yields suitable mechanical properties [5]; ferroic materials which are used for actuation and control [6]; various ceramics and minerals [6], etc. In materially uniform bodies, the heterogeneities, including the dislocations ( [7,8], Chapter 6 of [2]), accumulated plastic strains and shear bands [7,[10][11][12][13]15], crack tips [16], free surface [8,9], anti-phase boundaries [8], or any other regions within the materials with concentrated stresses [17,18], etc., are usually the preferred sites for nucleation of M in a single grain or polycrystalline samples of materials capable of undergoing martensitic transformations (MTs). The reduction in energies during MTs at other heterogeneous sites such as the matrix-precipitate interfaces [19], external surfaces of the samples [9,18,[20][21][22], and heterophase interfaces [23,24] also promotes the nucleation of M. On the other hand, point defects such as vacancies, interstitials, and ani-site defects may suppress the nucleation of M by significantly reducing the transformation temperatures [25,26].…”

“…It is to be mentioned that none of the existing papers on MTs in polycrystalline solids [15,81,[97][98][99][100][101][102][103][104][105][106][108][109][110][111][112][113][114][115][116][117] studied the role of the GB width on the temperature of nucleation of the phases and the subsequent microstructure evolution. The change in GB energy due to MTs, an important material parameter discussed above, is also yet to be incorporated to develop a robust model.…”

“…Furthermore, the role of the TJ energy on GB-induced MTs is not yet studied. The PF models in [15,[97][98][99][100][101][102][103][104][105][106][108][109][110][111][112][113][114][115] considered small strains, whereas the MTs usually involve large strains, and hence a large strains-based general PF model for MTs in polycrystals is yet to be developed. Recall that the only large strains-based model in [116,117] has issues with the kinematic model, as pointed out above.…”

Turbulent shear flow of solids

“…Investigations of SST as a stochastic nonlinear phenomenon is of great scientific significance, as it has certain universality and can occur at different length scales: from laboratory experiments to processes in the Earth's lithosphere [20]. The phenomenon is also of practical importance, as SST opens an avenue for solid-state mixing and physicochemical reactions under high pressure, whose potentialities in materials engineering can hardly be overestimated [13,21]. Indeed, SST offers an ecologically advantageous alternative to conventional metallurgical processing.…”