Shape Memory Alloys (SMAs) is a class of smart materials with the ability to remember the original shape. SMAs exhibit stress-induced martensitic transformation through twinning which is an important deformation mechanism that renders strength and ductility. Tailoring the capability of alloys for deformation twinning enables to optimize their mechanical performance. This paper presents a comprehensive review on the effect of internal and external parameters on the twinning propensity. Among these parameters, the effect of the composition, grain size, temperature and strain rate will be explored. In addition the use of shape memory phase as a strategy to improve the ductility of metallic use memory behaviour is of great importance to develop SMAs for multiple applications including mechanical, automotive, aerospace, civil and biomedical industries. A tentative outlook about the challenges and proposed solutions will be also discussed.

Textile Bewehrungen in Form von bi‐ oder multiaxialen Gittergelegen aus Hochleistungsfilamentgarnen, insbesondere aus Carbon, bieten durch ihre gestreckten Fadenlagen sowie die variablen Anordnungsmöglichkeiten der Verstärkungsgarne ein hohes Festigkeits‐ und Steifigkeitspotenzial entlang der Faserrichtung. Darüber hinaus zeichnen sie sich durch hohe Handhabbarkeit und eine sehr gute chemische Beständigkeit aus. Die bisherigen Forschungen auf dem Gebiet der bautechnischen Verstärkung und Instandsetzung haben gezeigt, dass textile Gitterstrukturen aus Carbongarnen als Bewehrungen im Beton fungieren und eine hervorragende Alternative zur Betonstahlbewehrung sowie Ergänzung zu den bisher verwendeten Verstärkungs‐ bzw. Instandsetzungsmethoden darstellen können. Die Grundlagen für die Entwicklung und Herstellung derartiger textiler Bewehrungen wurden in langjähriger Forschungsarbeit am Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik (ITM) der Technischen Universität Dresden gelegt und spiegeln im internationalen Maßstab den Stand der Technik auf diesem Gebiet wider. Gleichzeitig wurden am ITM die technischen Voraussetzungen geschaffen, mit modernen und hochproduktiven Multiaxial‐Kettenwirkmaschinen leistungsfähige und anforderungsgerechte Bewehrungsstrukturen unter industriellen Bedingungen fertigen zu können. Diese Textilbewehrungen sind inzwischen in die Industrie überführt worden, haben bereits eine allgemeine bauaufsichtliche Zulassung (abZ) erhalten und werden von TUDATEX GmbH sowie V. FRAAS Solutions in Textile GmbH angeboten.Innovative textile reinforcements for concrete applicationsTextile Reinforcements made of high performance filament yarns in the form of biaxial or multiaxial open‐grid fabrics, esp. carbon, offer high strength and stiffness potential along the fiber direction due to their stretched filament layers and flexible arrangement possibilities of the reinforcing yarns. In addition, they are characterized by high handling capability and excellent chemical resistance. The recent research in the field of structural reinforcements and repair have shown that textile open‐grid fabric structures made of carbon yarns can act as reinforcement in concrete and provide an excellent alternative to the existing concrete steel reinforcement and repair methods. The fundamental work for the development and production of such textile reinforcements have been carried out in many years of research at the Institute of Textile Machinery and High Performance Material Technology (ITM), TU Dresden and is reflects the current state of the art on an international scale. Also, the technical expertise acquired at the ITM enables to produce application‐adapted, high performing textile reinforcements with the help of modern and highly productive multi‐axial warp knitting machines under industrial conditions as well. These textile reinforcements meanwhile have found industrial markets through cooperational activities with TUDATEX GmbH and V. FRAAS Solutions in Textile GmbH. They have received general construction approval as well and are now comercially available.

The stress-induced martensitic transformation of Cu 50 Zr 50 at. % shape memory alloy was tuned through microalloying and co-microalloying. The effect of microalloying elements Co or Ni individually or combined (i.e., co-microalloying) was investigated and compared at the macroand nanoscale. From nanoindentation experiments, change in the slopes of (P/h)-h curves, plastic index and recovery ratio after annealing were investigated: partial replacement of Cu by 1 at. % Ni was observed to promote twinning while for 1 at. % Co the twinning propensity decreased and co-microalloying using 0.5 at. % Co and Ni had an intermediate effect. The recovery ratio of the Cu 50 Zr 50 alloy, calculated from the volume change of a residual indent after annealing at 400 ˚C for 5 min after annealing at 400C for 5 min increased from 15.6 % to 19.5 % when substituting Cu by 1 at. % Ni. These results, obtained at the nanoscale, are in agreement with macroscale test observation, namely, differential scanning calorimetry and x-ray diffraction. Therefore, microalloying opens up possibilities for the development of more cost-effective CuZr alloys, with a view to develop commercial actuators that could replace costly NiTi alloys in the near future.

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Textile high-performance filament yarn subjected to extremely high thermal loads can be found in various technical application fields. Besides the mechanical loads, textile fiber materials have to also satisfy high safety requirements in these applications with respect to thermal loads. Some of the main fields of application in the field of mechanical engineering are turbines, drive devices, rocket components and fire protection coatings. Textile grid-like structures are also being increasingly used in civil engineering as reinforcements (textile concretes). The design and development of textile structures for these applications demands studying and acquiring the material behavior under high thermal loads. Neither sufficient data nor standardized testing methods have been extensively achieved for evaluating the tensile characteristics of filament yarns under thermal influences. Hence, studying the thermal behavior of these yarns, which are used as input material for the reinforcing structures, is essential. The impact of the standard atmospheric condition on the oxidation behavior of the yarns, as in the case of carbon filament yarns and their influence on the physicochemical and tensile mechanical properties, have to be studied as well. This paper aims to address this issue and provides an insight into the current research about the development and realization of a novel test stand and the subsequent study of tensile mechanical behavior for textile high-performance fiber material under extreme thermal loads together with their physicochemical behavior.