The influence of the solidification rate of the melt was investigated for amorphous metallic systems based on iron: Fe 60 Co 7 Cr (NHRP-6). Rapidly cooled (10 5 K·s -1 ) alloys in the form of tapes with a thickness of 35 µm showed lower microhardness and higher plasticity. The surface composition of bulk samples cooled at a rate of 10 3 K·s -1 differed from that of tape samples, due to slow diffusion and formation of two or three phases. Some samples were enriched with Cr, V, W, Mo, Nb, or Mn. Bulk alloys showed higher microhardness and lower plasticity than tape samples. Amorphous alloys based on Fe / Bulk and tape samples / Microhardness / Plasticity / Elemental composition Фізико-механічні властивості стрічкових та об'ємних зразків аморфних сплавів на основі FeДосліджено вплив швидкості гартування розплавів складнолегованих металевих систем на основі заліза: Fe 60 Co 7 Cr (NHRP-6) на їхні фізико-механічні властивості. Швидкогартованим (10 5 К·с -1 ) сплавам у формі стрічки товщиною 35 мкм характерна нижча мікротвердість і дещо вища пластичність. Склад поверхні об'ємних зразків, що формуються із швидкістю охолодження 10 3 К·с -1 , відрізняється від стрічкових за рахунок тривалішої дифузії і формування 2-3 фаз. Деякі з них збагачені Cr, V, W, Mo, Nb, Mn. Об'ємні сплави володіють вищою мікротвердістю, нижчою пластичністю в порівняні із стрічковими. Аморфні сплави на основі заліза / Об'ємні та стрічкові зразки / Мікротвердість / Пластичність / Елементний склад
О. Герцик, Т. Переверзєва, М. Ковбуз та ін. ISSN 2078ISSN -5615. Вісник Львівського університету. Серія хімічна. 2018 With the increase in the potential scanning rate in voltammetry analysis, the decrease in potential changes and the reduction of corrosion currents can be traced, indicating formation of corrosion products on the alloys surface (such as iron salts), which are soluble in sulfate acid. In conditions of additional load on samples of Fe 78.5 Ni 1.0 Mo 0.5 Si 6.0 B 14.0 cyclic potential scanning in 0.5 M aqueous solution of sulfate acid, a decrease in two orders of magnitude of corrosion currents can be observed, which can be explained by the formation of a protective layer on their surface, which consists mainly of insoluble in H 2 SO 4 iron sulfate. Modification of the Fe 78.5 Ni 1.0 Mo 0.5 Si 6.0 B 14.0 surface with layer of a heterofunctional oligomer based on vinyl acetate, 2-tert-butylperoxy-2-methyl-5-hexen-3-yne and maleic anhydride increases corrosion resistance of samples in 0.05 M sulfate acid. The investigated amorphous alloy can be recommended for use in a sulfuric acid, which facilitates its passivation. Modification of the alloy surface by thirty-minute formation of the oligoperoxide layer increases its corrosion resistance in 0.05 M aqueous solution of H 2 SO 4 , and further, apparently, such alloy can be used for fixing biologically active substanceson its surface.
Under such conditions amorphous samples are characterized by high corrosion resistance in comparison with crystalline steel and during the exposure for 24 days samples of amorphous alloys are passivated. Due to the slower cooling rate for the bulk samples (10 2-10 3 K/min) compared the tape (10 4-10 6 K/min) the dense oxide layers are formed on the surface of the bulk amorphous alloys, providing them the highest corrosion resistance. The microhardness of amorphous alloys exceeded the microhardness of steels in 4-5 times, especially after the previous low-temperature modification. After cooling at low temperatures the surface layers of the AMA are sealed. Considering the high corrosion resistance we recommend amorphous alloys for laser coatings (lamination) of agricultural machines, which contact with different aggressive media. They also can be applied to the forest industry, the peat cutting, the grinding of garbage, and also to the military industry.
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