Search Results for nitinol

Fig. 24 Scanning electron microscopy micrographs showing (a) nitinol stent strut cracking and (b) fatigue fracture surface after prolonged ultrasonic cleaning More

Fig. 26 Scanning electron microscopy images of fractured low-strength nitinol wire device. (a) Overview of fractured wire showing secondary cracks at the compressive side of the sharp shape-set bends, as marked by white arrows. (b) High-magnification view of fracture surface exhibiting More

Fig. 26 (a) Nitinol wires. (b) General view of the fracture surface showing surface defects and massive corrosion, magnification 150×. (c) Detail of the fracture surface showing a ductile fracture, magnification 3500×. (d) Acicular microstructure and the progression of lateral cracking. (e More

Fig. 27 SEM image of fractured nitinol stent More

Fig. 28 SEM image of striations on fractured nitinol stent More

Fig. 29 SEM image of cracks from other locations on the nitinol stent More

Fig. 30 SEM image showing a nitinol wire in compression with cracks at the intrados and no cracking at the extrados More

Fig. 32 SEM image of compression-induced cracks in a nitinol wire sample subjected to 50% strain More

Fig. 33 SEM image of slip lines and cracks in a compression-damaged nitinol wire sample subjected to 31% strain More

Fig. 34 Metallographic image of intrados cracks in compressed and released nitinol wire sample. Cracks initiate in shear during compression and grow in tension upon release More

Fig. 37 Martensite in nitinol (Ni-50at.%Ti) shape memory alloy revealed by etching using equal parts HNO 3 , acetic acid, and hydrofluoric acid, and viewed using bright field (a) and Nomarski DIC (b). Nomarski DIC reveals more detail compared with bright field. More

Fig. 5 Elastic strain characteristics of Nitinol. Adapted from Ref 43 More

Fig. 18 Laser-welded microforceps made from Nitinol. Source: Ref 1 More

Fig. 7 Typical stress-strain curve for Nitinol deformed to fracture above its M d temperature, where it can no longer transform to martensite. In this case, the specimen is 50.8 at.% Ni wire, and the test temperature is 160 °C (320 °F). More

Fig. 10 Schematic map of apparent yield stress of Nitinol showing three distinct regions. Below M s , yielding is governed by the resistance to twin-boundary movement (solid line). Above M d , dislocation slip in the austenitic phase controls yielding (dashed line). Between M s and M d More

Fig. 15 Traditional S - N curves for two fully annealed binary Nitinol alloys, one with M s = −30 °C (22 °F) and the other with M s = 70 °C (160 °F), representing typical stress-controlled fatigue. The reported stress is the total cyclic stress (σ max − σ min ), or two times the amplitude More

Fig. 2 Ductile torsion fracture in Nitinol wire. Fracture surface is parallel to maximum shear stress. More

Fig. 4 SEM image of microvoid coalescence in Nitinol from uniaxial tensile loading More

Fig. 6 SEM image of directional microvoid coalescence in a Nitinol wire that fractured in bending (arrow identifies the crack growth direction) More