Microstructure and mechanical properties of constrained shape-memory alloy nanograins and nanowires

Abstract

We use the phase-field method to study the martensitic transformation at the nanoscale. For nanosystems such as nanowires and nanograins embedded in a stiff matrix, the geometric constraints and boundary conditions have an impact on martensite formation, leading to new microstructures --such as dots aligned on a square lattice with axes along <01>-- or preventing martensite formation altogether. We also perform tension tests on the nanowires. The stress-strain curves are very different from bulk results. Moreover, they are weakly affected by microstructures -- the mechanical response of nanowires with different microstructures may be similar, while nanowires with the same microstructure may have a different mechanical behavior. We also observe that at the transition temperature, or slightly below it, the narrowest wires behave pseudoelastically whereas wider wires are in the memory-shape regime. Moreover the yield stress does not change monotonically with width: it has a minimum value at intermediate width.

10 pages, 27 figures

References in corpus (3)

• Disorder-Driven Pretransitional Tweed in Martensitic Transformations
• Interplay between diffusive and displacive phase transformations: TTT diagrams and microstructures
• Effect of lattice mismatch-induced strains on coupled diffusive and displacive phase transformations

Cited by in corpus (8)

• A Nanoscale Shape Memory Oxide
• Phase-Field Reaction-Pathway Kinetics of Martensitic Transformations in a Model Fe3Ni Alloy
• Shape Memory Alloy Nanostructures With Coupled Dynamic Thermo-Mechanical Effects
• Phase-field modeling of paramagnetic austenite-ferromagnetic martensite transformation coupled with mechanics and micromagnetics
• Phase field simulations of coupled phase transformations in ferroelastic-ferroelastic nanocomposites
• Three Dimensional Non-Isothermal Ginzburg-Landau Phase-Field Model for Shape Memory Alloys
• Effect of Aspect Ratio and Boundary Conditions in Modeling Shape Memory Alloy Nanostructures with 3D Coupled Dynamic Phase-Field Models
• 3D Coupled Thermo-Mechanical Phase-Field Modeling of Shape Memory Alloy Dynamics via Isogeometric Analysis