This paper investigates the growth, characterization and electrochemical corrosion properties of tricalcium phosphate (TCP) doped with 0 wt. %, 1 wt. %, 5 wt. % and 10 wt. % of silver coatings deposited on magnesium substrate using pulsed laser deposition (PLD). The phase and morphological properties of the coatings were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The SEM images showed that increasing the percentage of Ag dopant reduces the size of droplets formed during the deposition process. The corrosion protection behavior of the coated samples were evaluated using potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS). The corrosion test were performed in Hanks' Balanced Salt Solution and 0.9 wt. % saline solution using three electrode electrochemical cell. The results showed that TCP coated magnesium exhibits a much superior stability and lower corrosion rate compared to bare Mg. It was observed that increasing the mass of the Ag dopant increases the corrosion protection, but 10 % Ag doping in TCP reduces the corrosion protection behavior. In conclusion, we have developed TCP and TCP doped with 1 %, 5 % and 10 % Ag coating with tunable corrosion protection efficiency.

The magneto-thermoelectric generator (MTG) converts wasted thermal energy into electrical energy in two steps. The first step involves thermal to mechanical energy conversion through balance of magnetic and elastic forces and the second step involves mechanical to electrical energy conversion through piezoelectric effect. The requirements for soft magnetic material in improving the efficiency of first step were identified and met through the design of a composite architecture. The Curie temperature of La(1–x)SrxMnO3 can be engineered to be near room temperature by modifying the Sr content. Composite of La0.85Sr0.15MnO3 (LSMO) and Ni0.6Cu0.2Zn0.2Fe2O4 (NCZF) was found to exhibit high saturation (Ms) and remnant (Mr) magnetization magnitude while maintaining the soft magnetic nature. Two-step sintering was found to prevent the inter-diffusion of LSMO and NCZF phases and provided high density without grain growth. The LSMO-NCZF (70:30 wt%) composite exhibited a large variation in Ms with respect to the change in temperature near Curie temperature which meets the requirements for efficient operation of MTG. The fabricated MTG using LSMO-NCZF (70:30 wt%) composite reached 0.2 Hz operational frequency and generated electrical output voltage of 2 Vp–p and peak power of 17 µW under the thermal gradient of 80 °C (0 °C/80 °C).

Niobium-containing ferritic stainless steels are finding new applications in automotive exhaust components because of their oxidation resistance, thermal fatigue resistance, and high-temperature strength. The mechanical behavior of Nb-containing ferritic steels at service temperatures of 973K(700°C) and higher results from the convolution of dynamic microstructural changes including precipitation, precipitate coarsening, strain hardening, recovery, and recrystallization. The relative contributions of these competing processes have yet to be clarified. In this study, the high-temperature flow strength of an 18Cr-2Mo-0.5Nb ferritic stainless steel (SUS 444) was correlated with microstructure under different strain and initial precipitate distributions to clarify the relative role of the strengthening and softening processes. High-temperature tensile tests at 1023K(750°C) of un-aged (initial 2 microstructure is precipitate-free) and pre-aged (initial microstructure contains precipitates) samples were carried out and transmission electron microscopy was used to assess dislocation distributions and precipitate morphology. The difference in the stress-strain curves between un-aged and pre-aged samples was drastic; the yield strength of the un-aged sample was twice that of the pre-aged sample, and the unaged sample exhibits a noticeable yield drop. Transmission electron microscopy revealed a Laves phase nucleated and grew during the high-temperature tensile test in the un-aged sample and the majority of the precipitates in the pre-aged sample were the same Laves phase. Furthermore, a strain effect on precipitate growth was recognized in un-aged and pre-aged conditions by comparing grip (no strain) and gauge (strained) sections of tensile samples. The dominant strengthening contribution in un-aged samples is initially the precipitate shearing mechanism and it changes to Orowan strengthening beyond the ultimate tensile strength, whereas the dominant contribution in the pre-aged samples appears to be Orowan strengthening throughout the stress-strain curve.

We report a class of amorphous thin film material comprising of transition (Fe) and Lanthanide metals (Dy and Tb) that show unique combination of functional properties. Films were deposited with different atomic weight ratio (R) of Fe to Lanthanide (Dy + Tb) using electron beam co-evaporation at room temperature. The films were found to be amorphous, with grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy studies indicating that the films were largely oxidized with a majority of the metal being in higher oxidation states. Films with R = 0.6 were semiconducting with visible light transmission due to a direct optical band-gap (2.49 eV), had low resistivity and sheet resistance (7.15 × 10−4 Ω-cm and ~200 Ω/sq respectively), and showed room temperature ferromagnetism. A metal to semiconductor transition with composition (for R < 11.9) also correlated well with the absence of any metallic Fe0 oxidation state in the R = 0.6 case as well as a significantly higher fraction of oxidized Dy. The combination of amorphous microstructure and room temperature electronic and magnetic properties could lead to the use of the material in multiple applications, including as a transparent conductor, active material in thin film transistors for display devices, and in spin-dependent electronics.