Nanocomposites and nanomaterials
Effect of Ar+ treatment on thermal stability and micromechanical properties of Fe75Mo5Si6B14 amorphous alloy 

Tsaregradskaya T.L., Kozachenko V.V, Ovsiienko I.V., Saenko G.V., 
Kuryliuk A.M.,  Turkov O.V., Maidanyk B.O.

Taras Shevchenko National University of Kyiv, Department of Physics
01601, Volodymyrska st. 64/13, Kyiv, Ukraine
E-mail: tsar_grd@ukr.net

Amorphous alloys, or metallic glasses, are materials with homogenous and isotropic structure, lacking long-distance order in atom arrangement. Such structure leads to a specific combination of mechanical and functional properties which makes them ideal for various applications. Amorphous alloys are kinetically and thermodynamically metastable and can exist in a certain range of certain parameters such as temperature, pressure, etc. Outside these ranges, they tend to stabilize through crystallization, usually resulting in a loss of favorable functional properties. Extending the ranges of amorphous alloys existing and controlling their mechanical properties is an important task. We tried solving this problem by   amorphous alloy surface treating with Ar+ ions.
Experimental studies were performed to determine the effect of Ar+ treatment on the parameters of thermal stability and micromechanical properties of Fe75Mo5Si6B14 amorphous alloy. The amorphous alloy treatment with argon ions was performed at the following parameters: the voltage at the anode was of 1 kV, the current through the sample was of 1 mA. The morphology study of the surface of the amorphous alloy were performed using LensSEI SEM. The parameters of thermal stability of the amorphous alloy were determined using a highly sensitive dilatometric technique. It is shown, that after Ar+ treatment of the amorphous alloy for (5-25) minutes, the thermal stability interval expanded by (30-120) K, respectively. When treating an amorphous alloy by Ar+ for (5-15) minutes, the relative change in microhardness is (2.5-4)%, ie is within the experimental error (5%). When treating Fe75Mo5Si6B14 amorphous alloy for 25 minutes, the microhardness decreases by 13%, ie the effect of plasticization is observed. The effects of expanding the interval of thermal stability and plasticization of the amorphous alloy can be explained by the dissolution of frozen crystallization centers. This fact is confirmed by studies of the morphology of the amorphous alloy surface. The surface of the amorphous alloy changes dramatically after Ar+ treatment: small grains disappear, which indicates that frozen crystallization centers dissolve in the amorphous matrix due to action of argon ions flux.