Current achievements on superplasticity and related phenomena at the Institute for Metals Superplasticity Problems

Abstract

A short review on the results of research and development on superplasticity of alloys and related processes such as grain refinement, solid state bonding carried out at the Institute for Metals Superplasticity of the Russian Academy of Sciences (IMSP RAS) is given. One of the most important contributions of IMSP RAS to the fundamentals of superplasticity consists in a development of the theory of superplastic flow based on the notion of cooperative grain boundary sliding. Main bases and results of this theory are presented. Since achieving superplasticity requires the formation of ultrafine grained microstructures in alloys, methods for grain refinement have been developed. The principles of the method of multiple isothermal forging invented at IMSP RAS, which allows refining grains in a wide range of metals and alloys down to the submicron and nanometer sizes, are reported. The method is capable of fabricating large bulk and sheet semiproducts with an UFG structure. The most important achievements in enhancing the characteristics of superplasticity of aluminum and intermetallic alloys are reported. Also, significant results have been obtained in the studies of diffusion bonding of similar and dissimilar materials, superplastic forming of hollow structures. These results have been used in the development of a technology for fabrication a titanium wide-chord hollow fan blade for the indigenous fifth-generation aircraft engine PD-14, which has been certified quite recently. Finally, results of finite-element modeling of superplastic forming processes are reviewed shortly.