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The amorphous alloy Fe75Mo5Si6B14 has been shown for investigations. It is shown that the interval of thermal stability has expanded by 80–120 K after ion treatment of the amorphous alloy for 5–25 min, respectively. When Fe75Mo5Si6B14 amorphous alloy treated with Ar + for (5–10) minutes, the relative change in microhardness is of 2.5%–4%, that is, it is within the experimental error of 5%. When the alloy treated for 15–25 min, the microhardness decreases by 7%–13%, that is, a plasticization effect is observed. The effects of expansion of the thermal stability interval and plasticization of an amorphous alloy can be explained by the dissolution of frozen centers of crystallization. This fact is confirmed also by SEM studies of the surface morphology of the amorphous alloy. [ABSTRACT FROM AUTHOR]

The micromechanical properties of amorphous alloys Co67Fe3Cr3Si15B12 and Ni40Fe40B20 are nonmonotonically dependent on time of exposure in the magnetic field is established in the work. Magnetic treatment causes two competing processes that cause changes in the microhardness and temperature of the onset of intense crystallization. The first is fast-acting, associated with the decay of clusters (borides and silicides), that causes plasticization (reduction of microhardness by (22–27)%) and increase the temperature of thermal stability by (50–70)°C. The second process is long-term, associated with the growth of frozen crystallization centers. This process leads to a strengthening of the structure and, as a result, to decrease in the magnitude of magnetoplastic effect and the effect of thermal stability increasing. [ABSTRACT FROM AUTHOR]

For amorphous alloy Fe77,5Ni3,5Mo1Si2B16 the possibility of obtaining the amorphous-nanocrystalline state by controlled annealing of source alloy is evaluated. Based on theory of high-temperature stability of amorphous alloys the temperature interval in which the condition of growth of frozen-in crystallization centers is fulfilled, but the process of intensive crystallization has not yet begun, is calculated. With proposed method alloy in the amorphous-nanocrystalline state is obtained, that is confirmed by the results of X-ray diffraction and electron microscopic studies. Using the highly sensitive dilatometric technique, the onset temperatures of intense crystallization for the source amorphous alloy and for alloy in the amorphous-nanocrystalline state have been determined. It has been shown that the proposed heat treatment reduces the onset temperature of intense crystallization by 15°С. Calculated according to the dilatometric experiment, the part of the nanocrystalline phase in the obtained amorphous-nanocrystalline specimen does not exceed 24%. In the paper the micromechanical and electrical properties of obtained alloy in the amorphous-nanocrystalline state are investigated. [ABSTRACT FROM AUTHOR]

To develop new amorphous, amorphous-nanocrystalline and nanocrystalline materials, optimize their unique properties and successfully operate their products, knowledge of changes in their structure under the influence of external factors is required. For the practical use of amorphous metal alloys, it is important to have data on the stability or changes in their properties under the action of magnetic fields, since products based on them are often operated under conditions of prolonged exposure to this factor. An experimental study of the influence of a constant weak (B = 0.64 T) magnetic field on the micromechanical properties and thermal stability of amorphous Co67Fe3Cr3Si15B12 and Fe40Ni40B20 alloys was conducted. It is established that the long-term action of a weak constant magnetic field leads to a magnetoplastic effect: the microhardness of amorphous alloys decreases up to 18-21 % per 100 days. Results of dilatometric experiments indicate that after treatment of amorphous Co67Fe3Cr3Si15B12 and Fe40Ni40B20 alloys by a weak magnetic field, the temperature of the intense crystallization onset increases by 40-80 K, that is, the interval of thermal stability of the alloy expands. The established effects can be explained by the fact that the magnetic field creates magnetoelastic dynamic stresses that destroy borides and silicides in the amorphous alloy, which promotes the homogenization of its structure. This causes the destruction of frozen-in crystallization centers and the formation of a new, more stable structural state with other short-range parameters and the level of internal stresses caused by the processes of structural relaxation. [ABSTRACT FROM AUTHOR]

One of the most important trends in modern physics of condensed state is the study of amorphous metallic alloys in metastable state, because their properties essentially depend on the influence of external conditions, especially in the region of phase transitions. External actions, such as low temperature annealing and mechanical treatment, lead to a change in the structure and physical properties of amorphous alloys. Effect of ultrasonic mechanical activation on the structure and properties of amorphous metal alloys is studied not enough, so such research is a relevant task. The aim of the work is an experimental study of the effect of ultrasonic treatment on thermal stability of the amorphous alloy Fe76Ni4Si14B6. The results of dilatometric studies show the increase in crystallization temperature of the samples of amorphous alloy Fe76Ni4Si14B6, that is, the expansion of thermal stability interval of the alloy, after ultrasound treatment. When intensity of ultrasonic treatment is 1 W/cm2, the temperature of intensive crystallization beginning increases by 30 K regardless of processing time (1-100 min), and with intensity of ultrasonic treatment of 2 W/cm2, the temperature of intensive crystallization beginning increases by 50 K regardless of processing time (1-80 min). As a parameter for comparing the mechanical properties of the amorphous alloy before and after ultrasonic treatment, microhardness was used. Microhardness of the amorphous alloy after ultrasonic treatment is reduced by 15 %, which indirectly confirms the fact that percentage of crystalline phase in the alloy is reduced by reducing size of frozen-in crystallization centers. Increasing of the thermal stability interval of Fe76Ni4Si14B6 amorphous alloy and reducing of the microhardness can be explained by the fact that ultrasonic treatment leads to decrease in the size or dissolution of frozen-in crystallization centers, resulting in homogenization of the amorphous alloy structure. [ABSTRACT FROM AUTHOR]