T. Asai, M. Tokuda, T. Inaba, Mie University, Mie, Japan; K. Kitamura, Aichi University of Education, Kariya, Japan; Y. Yoshimi, Yoshimi inc., Obu, Japan; Y. Watanabe, K. Hattori, TOYO SEIKO CO.,LTD., Yatomi, Japan
Ti-Ni alloy is a functional material that has shape memory effect and superelasticity. This alloy widely used in industrial and bio-medical fields. However, almost all applications are limited to the use as wire or thin plate, because Ti-Ni alloy has two big problems of little processability and gravity segregation in casting. From above-mentioned point of view, in this research work, we adopted a self-propagating high-temperature synthesis (SHS) for making an ingot of Ti-Ni alloy without the gravity segregation, and tried to a centrifugal casting for making arbitrarily-shaped products. The mechanical properties (shape memory effect, superelastic property, and so on) of Ti-Ni alloy made by this new method were investigated by systematic experiments. Furthermore, in order to confirm these mechanical properties, the metallurgical properties (transformation temperature, crystallinity, and so on) were measured by differential scanning calorimeter (DSC) and X-ray diffraction (XRD). Moreover, shot peening which is kind of cold work was given to the specimen as substitute of strong processing, and it investigated about influence on the mechanical property improvement by processing. From these results, it was considered that Ti-Ni alloy manufactured by the centrifugal casting after the SHS could be used for practical applications, and that Ti-Ni SMA products with arbitrarily shape were realized by using this method.
Summary: Ti-Ni alloy is a functional material that has shape memory effect and superelasticity. This alloy widely used in industrial and bio-medical fields. However, almost all applications are limited to the use as wire or thin plate, because Ti-Ni alloy has two big problems of little processability and gravity segregation in casting. From above-mentioned point of view, in this research work, we adopted a self-propagating high-temperature synthesis (SHS) for making an ingot of Ti-Ni alloy without the gravity segregation, and tried to a centrifugal casting for making arbitrarily-shaped products. The mechanical properties (shape memory effect, superelastic property, and so on) of Ti-Ni alloy made by this new method were investigated by systematic experiments. Furthermore, in order to confirm these mechanical properties, the metallurgical properties (transformation temperature, crystallinity, and so on) were measured by differential scanning calorimeter (DSC) and X-ray diffraction (XRD). Moreover, shot peening which is kind of cold work was given to the specimen as substitute of strong processing, and it investigated about influence on the mechanical property improvement by processing. From these results, it was considered that Ti-Ni alloy manufactured by the centrifugal casting after the SHS could be used for practical applications, and that Ti-Ni SMA products with arbitrarily shape were realized by using this method.
