Physico-Chemical nanomaterials science 

Low-temperature modification of amorphous metallic alloys 
Fe-(Me)-Si-B 
Hula T.H.1, Hertsyk O.M.1, Kovbuz M.O.1, Yezerska O.A.2, Pandyak N.L.3, Tashak M.S.4
1 Faculty of Chemistry, Ivan Franko National University of Lviv, Kyryla and Mefodiya Str., 6, Lviv-79005, Ukraine. 
E-mail: djunjer1@gmail.com
2 Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Wiener Strasse 12, 28359 Bremen, Germany.
3 Ukrainian National Forestry University, Gen. Chuprynka Str., 103, Lviv-79057, Ukraine.
4 Lviv Polytechnic National University, S. Bandery Str., 12, Lviv-79013, Ukraine.

Rapid cooling, which is used in the technology of production amorphous metallic alloys (AMA), inhibits the diffusion processes in the solid phase [1]. As a result, amorphous metallic alloys do not have such defects as secondary phases, segregations, which are usually formed due to diffusion during slow cooling. Therefore, AMAs are considered to be ideal chemically homogeneous alloys, highly corrosion resistant, able to withstand extreme conditions and those could be nanostructured under temperature treatment. Applying of such alloys in conditions of extreme temperatures, for example, in the space industry, requires an investigation of the dependence of structural and electrochemical parameters of amorphous alloys Fe80,0Si6,0B14,0 (AMA-1); Fe78.5Ni1.0Mo0.5Si6.0B14.0 (AMA-2); Fe73,1Cu1,0Nb3,0Si15,5B7,4 (AMA-3) and Fe59Ni26Cr6,6Mo0,9V1,6W0,3Si3B2,9 (AMA-4) from low temperature treatment at 77 K.
X-ray investigation of AMA samples Fe-(Me)-Si-B cooled at T = 77 K showed that after such low-temperature treatment there are no significant changes in the structure [2]. Evaluation of the microhardness of samples exposed to low temperatures showed that cooling AMA-2 and AMA-3 to T = 77 K increases the microhardness of such alloys, for multicomponent AMA-4 change is nonlinear. AMA-2 was the least sensitive to cooling. One-hour exposure at T = 77 K strengthened the surface of AMA-3 most significantly, while for multicomponent AMA-4 one- and three-hour exposure reduced the strength of the alloy surface. Fluctuations in the hardening coefficients for the investigated amorphous alloys in the vicinity of the unit demonstrate the high mechanical stability of the AMA surface.
Stabilization of electrochemical parameters in 0,5 M aqueous solution of NaCl amorphous metallic alloys after cooling them at T = 77 K promotes their further investigation in other aggressive environments.
1.	Sheng Guo, Yong Liu. Estimation of critical cooling rates for formation of amorphous alloys from critical sizes // J Non-Cryst Sol.-2012.-358.-P. 2753- 2758.
2.	Hertsyk O.M., Kovbuz M.A., Pereverzeva T.G., Boichyshyn L.M., Kotur B.Ya. An effect of low temperature processing on stability of physical and chemical properties of amorphous alloy Fe78,5Ni1,0Mo0,5Si6,0B14,0 // Rus J Appl Chem.-2013.-86, N 6.-Р. 802-806.