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Pure NiO and NiO thin films doped with 0.1 to 25% Cu were grown on pre-heated soda-lime glass substrates via spray pyrolysis technique. The surface roughness of the NiO:Cu thin films decreased as Cu/Ni ratio was increased. Antifungal activity of these thin films against Aspergillus niger (A. niger) which affects some of the fruits, and Macrophomina phaseolina (M. phaseolina) which is a soil borne fungus responsible for the infection of root and lower stem of several plants, was then investigated by bioassay and broth dilution methods. The antifungal response of pure NiO thin film was weak but it improved considerably on doping with copper. The higher the copper content in NiO:Cu thin film, the better was its antifungal response. Moreover, for the given Cu/Ni ratio range of 0–25%, the optical density (OD) of Potato Dextrose (PD) broth inoculated with A. niger and containing NiO:Cu material was reduced or antifungal ability was enhanced by 8.3, 9.9, 11.7, and 13.4 times for the exposure time of 6, 8, 10, and 12 days, respectively. Similarly, the OD of PD broth inoculated with M. phaseolina and containing NiO:Cu material was reduced or antifungal ability was enhanced by 16–37 times in the exposure temperature range of 20–40 °C. A linear relationship of OD with crystallite size and lattice strain of the thin films showed that NiO:Cu material possessed memory of the structural modifications induced by the dopant atoms though its phase changed from crystalline to non-crystalline state. These results can be utilized in agricultural sector. [ABSTRACT FROM AUTHOR]

Five W-alloy specimens, containing 8.57% Ni, 6.34% Cu, and 1.34% Mo, were bombarded with 5.2 MeV singly charged nitrogen ions. The ions dose range was 5 × 1014–1 × 1016 ions/cm2. XRD patterns portrayed diffraction peaks of pure W as well as of Cu0.4W0.6, MoNi4, and Ni4W phases. Harris analysis showed that the preferentially oriented planes depend on the nitrogen ions dose. The structural parameters, namely lattice strain and crystallite size, vary with nitrogen ions dose alike. Same pattern is followed by surface hardness and electrical resistivity. The increase in the values of all the parameters with ions dose is rapid in the range 0–1 × 1015 ions/cm2 and later on slow till the maximum ions dose 1 × 1016 ions/cm2. However, the interdependence of each parameter on the other ones was linear. Surface roughness of the specimens was found to decrease on increasing ions dose. On the other hand, surface hardness registers a rise as crystallite size increases, and hence follows Inverse Hall–Petch relation. [ABSTRACT FROM AUTHOR]

Structural material AA-7075-T6, an aluminium-based alloy, was subjected to thermal exposure for 60 min in the temperature range 100–300 °C with an interval of 20 °C. Harris analysis of the XRD patterns of specimens showed that the un-exposed AA-7075-T6 material was texture free, but upon thermal exposure, it developed texture. The crystallite size and lattice strain of the specimens were evaluated by Williamson-Hall analysis of the XRD patterns. Thermal exposure in the temperature range 100‒200 °C had no noticeable effect on the surface hardness. However, it decreased rapidly with the increase in temperature from 200 to 300 °C. This behaviour was accounted for in terms of dislocation glide by Orowan mechanism in an atmosphere of semi-coherent ή precipitates (MgZn2) in the main matrix. Breakdown of Hall–Petch relation established that crystallite boundaries do not make any significant contribution to the surface hardness, but the resistance to glide dislocations is offered by the semi-coherent ή precipitates (MgZn2) present in the matrix. [ABSTRACT FROM AUTHOR]

Zinc single crystal specimens were irradiated with pulsed Nd:YAG laser in vacuum. Keeping the number of laser shots constant (10 shots), laser energy was varied from 50 to 150 mJ, whereas the corresponding laser fluence was 97 to 292 J cm−2, respectively. Using optical microscope, the dimensions (area and perimeter) of laser ablated region on the surface of each specimen were measured. Both parameters increased, in general, on increasing laser pulse energy. Examination of surface morphology by scanning electron microscope revealed formation of pores, grooves, cracks, bubbles, micron-size rods, ripples, ridges, cavities, microcones, and solid flakes, etc. Surface roughness had no systematic dependence on the laser pulse energy. Structural parameters, i.e., texture coefficient, lattice strain, and crystallite size, were determined by means of Harris analysis as well as Williamson–Hall analysis of the XRD patterns of specimens. The variation of lattice strain and crystallite size with laser fluence or laser pulse energy was alike. Surface hardness decreased on increasing laser fluence, and followed classical Hall–Petch relation. [ABSTRACT FROM AUTHOR]

Microstructure of Cu-10wt.%Sn alloy, prepared by powder metallurgy technique and sintered at 900 °C for 120 min in hydrogen atmosphere, was studied by optical microscopy and XRD technique as a function of aging time. Isothermal aging of the alloy specimens was performed at 250 °C for a period of 30, 60, 120, 300, and 1440 min after solution treatment at 500 °C for 60 min. Rockwell hardness of aged specimens was also measured at room temperature as a function of aging time. It was observed that microstructure of the as-sintered specimens consists of the grains of alpha Cu-Sn solid solution. Moreover, solution treatment of the alloy specimens followed by quenching in water increased the hardness of the as-sintered alloy specimens from 35.5 to 59.8 HRF due to the residual stresses generated by fast cooling. Aging at 250 °C for 30, 60, and 120 min was found to cause a decrease in hardness from 59.8 to 45.1 HRF, whereas the specimens aged for 300 and 1440 min show an increase in hardness from 45.1 to 75.7 HRF. The values of porosity calculated from XRD patterns of the alloy specimens referred to show that porosity varies with aging time in a manner opposite to that of hardness, e.g., porosity is maximum for 120 min aging time where hardness is minimum. [ABSTRACT FROM AUTHOR]

Available data on the temperature and concentration dependences of the critical resolved shear stress (CRSS) of KBr–KCl solid-solution crystals containing 8–41 mol% KCl in the temperature range 77–230 K have been analysed within the frame work of the kink-pair nucleation model of plastic flow in solid-solution crystals. It is found that CRSS τ decreases with the increase in temperature T in accord with the model relation ln τ = A− BT, where A and B are positive constants. The CRSS τ at a given temperature depends on solute concentration c as τ ∝ c p , where exponent p has a value between 0.5 and 1 depending on the temperature at which deformation is carried out. The model parameter W o, i.e. binding energy between the edge-dislocation segment involved in the unit activation process and the solute atoms close to it ( T→0 K), which is inversely proportional to B, increases with solute concentration c monotonically in accord with the model prediction W o ∝ c 1/4 upto a critical value c m = 35 mol% KCl. However, W o decreases with increase in c beyond c m , which indicates somewhat ordered distribution of solute in the host lattice of concentrated solid-solutions with c > c m . [ABSTRACT FROM AUTHOR]