Fatigue Crack Growth in Austenitic and Martensitic NiTi: Modeling and Experiments

Fatigue crack-growth in shape-memory NiTi and NiTi–TiC composites

An experimental study was conducted to examine the room-temperature fatigue crack-growth characteristics of shape-memory NiTi matrix composites reinforced with 10 and 20 vol.% of TiC particles. Microstructural characterization of these hot-isostatically-pressed materials shows that the TiC particles do not react with the NiTi matrix and that they lack any texture. Overall fatigue crack-growth c...

Strain and texture evolution during mechanical loading of a crack tip in martensitic shape-memory NiTi

In situ synchrotron X-ray diffraction measurements are used to create two-dimensional maps of elastic strain and texture, averaged over a compact-tension specimen thickness, near a crack tip in a martensitic NiTi alloy. After fatigue crack propagation, the material ahead of the crack and in its wake exhibits a strong texture, which is eliminated by subsequent shape-memory heat treatment, indica...

Martensitic Transformation of NiTi and NiTi- TiC Composites

Fatigue-crack growth properties of thin-walled superelastic austenitic Nitinol tube for endovascular stents.

Over the past 10 years, the supereleastic nickel-titanium alloy Nitinol has found widespread application in the manufacture of small-scale biomedical devices, such as self-expanding endovascular stents. Although conventional stress/strain-life (S/N) analyses are invariably used as the primary method for design against fatigue loading and for predicting safe lifetimes, fracture mechanics-based m...

Incomplete self-similarity and fatigue-crack growth

The Paris power law, which relates fatigue-crack growth rates to the applied stress-intensity range, is an example of a scaling law with the inherent property of incomplete similarity. Previous considerations of dimensions and self-similarity have suggested that the assumed ‘materials constants’ in this law are also a function of specimen size. In this note, the question of the size-dependence ...