The phase-field microelasticity theory has exhibited great capacities in studying elasticity and its effects on microstructure evolution due to various structural and chemical non-uniformities (impurities and defects) in solids. However, the usually adopted linear and/ or collinear coupling between eigen transformation strain tensors and order parameters in phase-field microelasticity have excl...

Martensitic crystals which can undergo a cubic to tetragonal phase transformation have a nonconvex energy density with three symmetry-related, rotationally invariant energy wells. We give estimates for the numerical approximation of a first-order laminate for such martensitic crystals. We give bounds for the L2 convergence of directional derivatives in the “twin” plane, for the L2 convergence o...

The different contributions to the entropy change linked to the austenite-martensitic transition in a Ni-Mn-Sn metamagnetic shape memory alloy have been determined by combining different experimental techniques. The vibrational contribution has been inferred from the vibrational density of states of both the martensitic and austenite phases. This has been accomplished by combining time-of-fligh...

There have been considerable efforts to create welding consumables which on solid state phase transformation partly compensate for the stresses which develop when a constrained weld cools to ambient temperatures. All of these efforts have focused on structural steels which are ferritic. In the present work, alloy design methods have been used to create a stainless steel welding consumable which...

This work is to the best of my knowledge original, except where acknowledgements and references are made to previous work. Neither this, nor any substantially similar dissertation has been or is being submitted for any other degree, diploma or other qualification at any other university. This dissertation does not exceed 60,000 words in length. Abstract iii DFT Pak, Jun Hak 20080959 Coalesced s...

The subject of martensitic phase transformation is one of considerable scientific as well as technological interest. Among the martensitic materials, the "shape-memory" alloys have received special attention. ' These alloys exhibit curious elastic behavior near the martensitic transformation temperature (M, ): They can be strained beyond the elastic limit in a reversible manner. In some cases, ...

This paper reports a computer simulation of martensitic transformation in both Cu-Zn-Al and Fe-Ni-C alloys by a 2-dimensional model . The influence of the imposed stress on the mechanical behaviour, the transformation kinetics, and the microstructure are illustrated for Cu-Zn-A1 alloy. The study of transformation kinetics shows the following features: (1) in case of stress-free transformation, ...

The mechanical behaviour associated to the martensitic transformation has been modelled using a 2D FE description. The martensite variants are constituted of different elements of the mesh and four different variants are allowed to transform in the grain. The transformation progress is prescribed using a thermodynamical criterion based on the maximal work associated to the variant formation. Tr...

The electric resistance, sensitively dependent on the electronic structure and currently used to detect transformation temperatures in shape memory alloys, deserves attention also in the stress transformation domain. In fact, the electric resistance has already been investigated under increasing stress in the martensitic phase of several shape memory alloys: in this case a linear relationship i...