SUPERPLASTICITY

SUPERPLASTICITY, a state in which polycrystalline solid bodies are substantially deformed during tensioning (elongation of up to several thous. %, while for normal plastic deformation it can hardly reach dozens %). S. studies were started in 1970s in UAI (O.A.Kaibyshev, M.H.Rabinovich) and continued in mid ‘80s in the Institute of Metals Superplasticity Problems. They have developed the S. theory, defining the universal character of this phenomenon and the possibility of transferring practically any industrial alloy into the superplasticity state. S. was discovered and studied in hard‑to‑deform materials (intermetallides, ceramics). It was discovered that high‑speed and low‑temperature S. may occur when sub‑micro‑ and nanocrystalline structures are reached in the materials. They have proved the efficiency of S. use for local deformation of the material and acceleration of the welding process for non‑organic materials in solid state. Zero tolerance die forging technologies were developed for complex shape items, for gas turbines and car wheel discs, for production of composites, with matrices made of light alloys, derived from aluminium, magnesium and titanium, reinforced with high strength and modular boron fibres, die forging with pressure welding of cells and multi‑layer cellular structures. Studies of nano‑structural materials creation with the deformation processing method were initiated in 1989 by the Institute of Metals Superplasticity Problems, and in 1995 by the Institute of Physics of Advanced Materials. In 1978 Ufa hosted the 1st All‑Union Conference for metal S. In 1994, a visiting session of the International Conference for S. of Advanced Materials (16 countries) was held. The scientists of the Republic obtained more than 250 national and foreign patents for inventions related to S.