Deformation-induced Phase Transformations: On-Demand Poster Presentations
Program Organizers: Yangyang Zhao, Purdue University; Jonah Klemm-Toole, Colorado School of Mines; Amy Clarke, Los Alamos National Laboratory; Janelle Wharry, Purdue University
Friday 8:00 AM
October 22, 2021
Room: On-Demand Poster Hall
Location: MS&T On Demand
Wire Size Effect on the Nucleation of Fatigue Cracks Near Non-metallic Inclusions in Superelastic Nitinol
: Parisa Shabani Nezhad1; Jacob Rusch1; John Moore1; Dinc Erdeniz2; 1Marquette University; 2University of Cincinnati
Nitinol is a near-equiatomic alloy of nickel and titanium which has a wide range of applications due to its outstanding functional properties, such as shape memory and superelastic behavior. Superelastic nitinol wires, often used for the fabrication of stents, exhibit recoverable strains that are significantly greater than traditional alloys. This property arises from the transformations between the two phases, austenite and martensite, that it adopts near room temperature. In most of its applications, nitinol is cycled between these two phases, which results in functional and/or structural fatigue that ultimately leads to failure. It has been shown that the main fatigue crack initiation sites, other than surfaces, are microstructural inhomogeneities such as voids and non-metallic inclusions. In this work, nitinol wires with three different sizes are subjected to microstructural analysis and low-cycle fatigue tests to understand the effect of wire size on phase transformations and fatigue crack nucleation around non-metallic inclusions.