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Shape Memory and Superelasticity OnlineFirst articles

09.01.2019 | SPECIAL ISSUE: HTSMA 2018, INVITED PAPER

On the Oxidation Behavior and Its Influence on the Martensitic Transformation of Ti–Ta High-Temperature Shape Memory Alloys

In the present work, the influence of oxidation on the martensitic transformation in Ti–Ta high-temperature shape memory alloys is investigated. Thermogravimetric analysis in combination with microstructural investigations by scanning electron …

Autoren:
Dennis Langenkämper, Alexander Paulsen, Christoph Somsen, Jan Frenzel, Gunther Eggeler

20.12.2018 | Special Issue: HTSMA 2018, Invited Paper HTSMA Open Access

Tensile Deformation of Superelastic NiTi Wires in Wide Temperature and Microstructure Ranges

Superelastic NiTi wires were prepared from a single cold worked wire by various electropulse heat treatments. The wires having a wide range of virgin microstructures were subjected to tensile tests until rupture and cyclic superelastic tensile …

Autoren:
Yuchen Chen, Ondřej Tyc, Orsolya Molnárová, Luděk Heller, Petr Šittner

18.12.2018 | Special Issue: HTSMA 2018

A Kinetic Study on the Evolution of Martensitic Transformation Behavior and Microstructures in Ti–Ta High-Temperature Shape-Memory Alloys During Aging

Ti–Ta alloys represent candidate materials for high-temperature shape-memory alloys (HTSMAs). They outperform several other types of HTSMAs in terms of cost, ductility, and cold workability. However, Ti–Ta alloys are characterized by a relatively …

Autoren:
Alexander Paulsen, Jan Frenzel, Dennis Langenkämper, Ramona Rynko, Peter Kadletz, Lukas Grossmann, Wolfgang W. Schmahl, Christoph Somsen, Gunther Eggeler

09.12.2018

Assessment of Entropy Differences from Critical Stress Versus Temperature Martensitic Transformation Data in Cu-Based Shape-Memory Alloys

The entropy differences per unit volume (ΔStrans) between the close-packed phases in a martensitic transformation (MT) in Cu-based shape-memory alloys are obtained from mechanical tests by measuring, as a function of temperature (T), the critical …

Autoren:
J. L. Pelegrina, A. M. Condó, A. Fernández Guillermet

07.12.2018 | Special Issue: Htsma 2018, Invited Paper

Effect of Aging Heat Treatment on the High Cycle Fatigue Life of Ni50.3Ti29.7Hf20 High-Temperature Shape Memory Alloy

Shape memory alloys can be utilized as actuators for several applications in aerospace industry which require high strength and stable actuation cycles together with the transformation temperatures above 100 °C. Aging is one of the methods for …

Autoren:
Hasan H. Saygili, H. Onat Tugrul, Benat Kockar

07.12.2018 | Special Issue: HTSMA 2018, Invited Paper

Pathways Towards Grain Boundary Engineering for Improved Structural Performance in Polycrystalline Co–Ni–Ga Shape Memory Alloys

In recent years, Co–Ni–Ga high-temperature shape memory alloys (HT-SMAs) attracted a lot of scientific attention due to their superior functional material properties. In the single-crystalline state, Co–Ni–Ga HT-SMAs feature a good pseudoelastic …

Autoren:
C. Lauhoff, M. Vollmer, P. Krooß, I. Kireeva, Y. I. Chumlyakov, T. Niendorf

06.12.2018 | Special Issue: HTSMA 2018, Invited Paper

Reconciling Experimental and Theoretical Data in the Structural Analysis of Ti–Ta Shape-Memory Alloys

The structural characterization of the various phases that occur in Ti–Ta-based high-temperature shape-memory alloys is complicated by the presence of many competing phases as a function of composition. In this study, we resolve apparent …

Autoren:
Alberto Ferrari, Peter M. Kadletz, Tanmoy Chakraborty, Kunyen Liao, Dennis Langenkämper, Yahya Motemani, Alexander Paulsen, Yury Lysogorskiy, Jan Frenzel, Jutta Rogal, Alfred Ludwig, Christoph Somsen, Ralf Drautz, Wolfgang W. Schmahl

12.11.2018

Effects of Sn Addition on NiTi Shape Memory Alloys

NiTiSn shape memory alloys provide a cost-effective alternative to many NiTi-based low-temperature shape memory alloy systems such as NiTi: Cr, Co, and Nb. To demonstrate the viability of NiTiSn shape memory alloys for low-temperature actuator …

Autoren:
Avery W. Young, Tyler Torgerson, Nathan A. Ley, Keirsten Gomez, Othmane Benafan, Marcus L. Young