Cyclic degradation of titanium-tantalum high-temperature shape memory alloys - The role of dislocation activity and chemical decomposition

Titanium-tantalum shape memory alloys (SMAs) are promising candidates for actuator applications at elevated temperatures. They may even succeed in substituting ternary nickel-titanium high temperature SMAs, which are either extremely expensive or difficult to form. However, titanium-tantalum alloys show rapid functional and structural degradation under cyclic thermo-mechanical loading. The current work reveals that degradation is not only governed by the evolution of the ω-phase. Dislocation processes and chemical decomposition of the matrix at grain boundaries also play a major role.DFG/NI1327/3-1DFG/MA1175/34-1DFG/EG101/22-1DFG/FR2675/3-

Ingot metallurgy and microstructural characterization of Ti–Ta alloys

In the present work we perform a detailed investigation of ingot metallurgy processing routes of Ti-30Ta, a shape memory alloy with a good potential for applications at higher temperatures. There is currently considerable interest in high temperature shape memory alloys, both in industry (automotive and aerospace applications) and in academia. By means of scanning electron microscopy, we provide recommendations on the number of remelting cycles in the vacuum arc melting process, and on annealing temperatures/times in order to obtain chemical homogeneity. It is also shown that this is required to obtain well defined differential scanning calorimeter charts, which facilitates characterization and investigations of martensitic transformation in this alloy. Areas in need of further work are identified. Copyright © 2014 Carl Hanser Verlag GmbH Co. KG

Anisakid nematodes and anisakiasis

Anisakiasis (anisakidosis) refers to infection of people with larval stages of ascaridoid nematodes belonging to the family Anisakidae (and possibly also Raphidascarididae). These worms, commonly called anisakids, utilize aquatic mammals, piscivorous birds, aquatic reptiles, or fish as definitive hosts, and aquatic invertebrates and fish as intermediate or paratenic hosts