Papers by Author: Yu.V. Milman

Abstract: It is generally supposed that diffusion is the main factor controlling the process of powder sintering. In this work it is shown that plastic deformation achieved by means of dislocation movement is also an important constituent of the sintering process. Since temperature essentially affects dislocation mobility, the temperature ranges of cold, warm and hot deformation are discussed. The stresses occurring on powder sintering leading to plastic deformation of the material are estimated. On the base of results recommendations are made for selecting the optimal condition for the sintering of powders.

Abstract: Metal foams based on high-strength Al-Zn-Mg alloy are promising material for energy absorption application. The performance of coated calcium carbonate (CaCO3) as foaming agent for Alporas like route is studied in the present paper by comparison with the conventional titanium hydride (TiH2). Compressive response of the foams was examined and microstructure of cell wall was investigated. The advantages of CaCO3–foam are shown and discussed.

Abstract: The review of the works devoted to the influence of scandium on the structure, mechanical behavior and corrosion resistance of aluminum alloys is given. The wrought thermally non-hardenable alloys of Al- Mg system and thermally hardenable high-strength alloys of Al-Zn- Mg-Cu system are considered. The influence of Sc on the glass forming ability of amorphous alloys and on the superplastic behavior of aluminum alloys is discussed.

Abstract: Specific features of mechanical behaviour of ultra fine grained iron subjected to friction treatment with nitriding (FN) were clarified by comparison with that induced by friction treatment (FT) with air. Mechanical parameters such as Young’s modulus, nanohardness, and plasticity characteristic δA were found to be of high sensitive both to the scale of grain structure and to iron modification by nitrogen. Young’s modulus tends to decrease and Hall-Petch low fails to describe correlation between grain structure and hardness for submicro-grained and nanocrystalline iron. Hall-Petch coefficient, ky, decreases as grain size decreases within submicro-grained and, then, nano grained sections and it takes even negative value in nano grained section modified by nitrogen. Parameter δA is found to be dependent on combination of hardness and Young’s modulus, resulting in its variation with decreasing the grain size. The presence of secondary nanocrystalline Fe4N phase fundamentally changes mechanical behaviour of nanocrystalline iron, leading to strengthening the grain boundaries and triple junctions.

Abstract: Aluminum-based alloys containing quasicrystalline particles of 50 – 600 nm in diameter as a reinforcing phase were produced in the form of powder or ribbons by water atomization or melt spinning techniques, respectively. Rods were compacted from powders and some ribbons by severe plastic deformation without sintering. Structure and mechanical behavior of alloys are discussed.