Defect and Diffusion Forum Vol. 365

Abstract: Titanium alloys present favorable properties to industry applications that depend on their composition and microstructure. Adding alloy elements and thermomechanical treatments can change the microstructure of titanium alloys. In this paper, Ti-15Zr alloys with different molybdenum quantities were prepared and hot-rolled, having been previously subjected to homogenizing heat treatment. The results showed that the microstructure of the alloys was sensible to heat treatment, in accordance with the theoretical prediction from the molecular orbital method.

Abstract: The importance of leucoxene concentrates of Yaregskoye deposit as raw materials for pigmental dioxide production is shown in this paper. The technology of thermal activation of leucoxene concentrates is developed and tested in industrial conditions. The offered methods and technologies will allow providing in the long term domestic titanium-containing raw materials the pigmental industry of the Russian Federation.

Abstract: Anelastic properties of Bulk Metallic Glasses (BMG) were studied by mechanical spectroscopy using a flexural vibration apparatus. BMG’s samples, with nominal composition Cu₄₈Zr₄₃Al₉ and Cu₅₄Zr₄₀Al₆, were produced by skull push-pull casting technique in rectangular cavity cooper mold. In both samples, the differential scanning calorimeter patterns have evidenced the presence of amorphous structure, although the X-ray diffraction for Cu₄₈Zr₄₃Al₉ composition has shown a heterogeneous microstructure embedded in the amorphous matrix. Anelastic relaxation spectra were obtained using an acoustic elastometer system with vibration frequency in the kilohertz bandwidth, a heating rate of 1 K/min, vacuum greater than 10^-5 mBar in the temperature range of 300 K to 620 K. In the flexural apparatus, an acoustic elastometer system, the internal friction (energy loss) and the elastic modulus were obtained by free decay of vibrations and by the squared of the oscilation frequency, respectively. Internal friction spectra were not reproducible among the measurements, which may imply atomic rearrangement in the samples due to consecutive heating. Normalized elastic modulus data showed distinct behavior from the first to the other measurements evidencing irreversible microstructural alterations in the samples possibly associated with mechanical relaxation due to the motion of atoms or clusters in the glassy state.

Abstract: Cellulases, among many enzymes, have been highlighted in several areas of expertise, such as food, textiles, pulp and paper and wastewater treatment of effluents and residues. There is also the challenge of producing biofuels, where currently cellulases have been widely applied in the production of cellulosic ethanol, where it is used during the stage of hydrolysis of lignocellulosic biomass for conversion of cellulose to glucose. Studies have been developed in order to produce this enzyme through a process of solid state fermentation from lignocellulosic agroindustrial wastes, thus reducing the cost of enzyme production, and adding value to the residue. The aim of this work was to produce cellulases from the stalk of the cashew bagasse using Trichoderma reesei LCB 48. The study of the cellulase production was performed using 22 factorial design with central point in quadruplicate. The washed stalk of the cashew bagasse inoculated with T. reesei was evaluated for the production of cellulases with initial moisture contents of 45, 55 and 65% and in the presence of inorganic nitrogen ((NH4)₂SO₄) at concentrations 0.5, 0.75 and 1%. The fermentation was developed over 238 hours, and during this period the parameters analyzed were pH, moisture, AR and enzyme activity expressed in CMCase. Peak production of cellulase enzyme expressed in CMCase was achieved with 238 hours which value was 0.71 U/g (0.095 U/mL), under the conditions of 45% initial moisture content and 1% of nitrogen source. This activity was obtained in only one stage of the biotechnological process, the solid state fermentation; the next ones are concentration and purification. The using of experimental design methodology allowed us to observe the initial substrate moisture is the determining variable in the production of enzymes CMCases, and the minimum moisture level (45%) showed the highest production values of CMCase.