Open Access. Powered by Scholars. Published by Universities.®

Engineering Science and Materials Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 3 of 3

Full-Text Articles in Engineering Science and Materials

A Diffuse Interface Approach To Phase Transformation Via Virtual Melting, Kasra Momeni Jan 2015

A Diffuse Interface Approach To Phase Transformation Via Virtual Melting, Kasra Momeni

Graduate Theses and Dissertations

This work represents development of the first phase field models and detailed study solid-solid transformations via intermediate melting within nanometer size interface. Such phase transformations can occur in different materials, including HMX energetic crystals, PbTiO3 nanowires, complex pharmaceutical substances, electronic and geological materials, as well as colloidal, and superhard materials. A thermodynamically consistent phase field model for three phases is developed using two polar order parameters. It includes the effect of energy and width of solid-solid and solid-melt interfaces, interaction between two solid-melt interfaces, temperature, mechanics, and interface stresses. The derived thermodynamic potential satisfies all the equilibrium and stability conditions ...


Phase Field Approach For Multiphase Phase Transformations, Twinning, And Variant-Variant Transformations In Martensite, Arunabha Mohan Roy Jan 2015

Phase Field Approach For Multiphase Phase Transformations, Twinning, And Variant-Variant Transformations In Martensite, Arunabha Mohan Roy

Graduate Theses and Dissertations

New advanced phase field model of transformations between martensitic variants and multiple twinning within martensitic variants is developed for large strains and lattice rotations. It resolves numerous existing problems. The model, which involves just one order parameter for the description of each variant-variant transformation and multiple twinnings within each martensitic variant, provides a well-controlled description of variant-variant transformations and multiple twinning, including expressions for interface tension which are consistent with the sharp interface limit. The finite element approach is developed and applied to the solution of a number of examples of twinning and combined austenite-martensite and martensite-martensite phase transformations (PTs ...


Modeling And Simulations Of Strain-Induced Phase Transformations In Materials Under Compression And Compression-Torsion In Traditional And Rotational Diamond Anvil Cells, Biao Feng Jan 2015

Modeling And Simulations Of Strain-Induced Phase Transformations In Materials Under Compression And Compression-Torsion In Traditional And Rotational Diamond Anvil Cells, Biao Feng

Graduate Theses and Dissertations

Phase transformations (PTs) under high pressure and plastic shear are widespread in nature, physical experiments, and modern technologies. In order to study the effect of plastic deformations on PTs, a rotational diamond anvil cell (RDAC) and diamond anvil cell (DAC) without hydrostatic media are utilized, in which large plastic shear is superposed in the sample under high pressure. Such PTs are classified as strain-induced ones and they occur by nucleation at defects that continuously appear during the plastic deformation.

By applying finite element approach, plastic strain-induced PTs in a sample in DAC and RDAC are investigated in detail. A large-strain ...