Longitudinal Spin Seebeck Effect thermopiles based on flexible Co-rich amorphous ribbons/Pt thin-film heterostructures

Thermoelectric phenomena, such as the Anomalous Nernst and Longitudinal Spin Seebeck Effects, are promising for sensor applications in the area of renewable energy. In the case of flexible electronic materials, the request is even larger because they can be integrated into devices having complex shape surfaces. Here, we reveal that Pt promotes an enhancement of the thermoelectric response in Co-rich ribbon/Pt heterostructures due to the spin-to-charge conversion. Moreover, we demonstrated that the employment of the thermopiles configuration in this system increases the induced thermoelectric current, a fact related to the considerable decrease in the electric resistance of the system. By comparing present findings with the literature, we were able to design a flexible thermopile based on LSSE without the lithography process. Additionally, the thermoelectric voltage found in the studied flexible heterostructures is comparable to the ones verified for rigid systems.This research was funded by different sources. M.A.C. thanks CAPES (8887.573100/2020-00) and CNPq. A.F. thanks the FCT (CTTI-31/18-C.F. (2) junior researcher contract). A.V.S. and G.V.K. were supported in the frame of the Priority-2030 Program of Ural Federal University

Effect of small vanadium addition on the microstructure, transformation temperatures, and corrosion behavior of a Cu72Al17Mn11 shape memory alloy

In the present work, effects of 0.1 at.% and 0.2 at.% vanadium content on the microstructure, transformation characteristics and corrosion behavior of the Cu72Al17Mn11 shape memory alloy (SMA) have been investigated by means of OM, SEM, XRD, DSC measurements and corrosion test. The alloys were produced in an induction furnace under air atmosphere. The results indicate that microstructure at room temperature consisted of a mixture of β3(L21) parent phase with 0.06–0.08 at% of vanadium into solid solution, small amounts of a cubic bcc δ(V,Mn) precipitate, β1′(18R) and γ1′(2H) martensites. The small addition of vanadium contributes to the induction of martensite γ1′ and broads the hysteresis of the alloys. Thermal analysis evidences the shift of Af, Ms to higher temperatures, showing multi-stage phase transformations of the reaction β1′→γ1′→β3, which results in increased values of ΔHM→A, ΔSM→A, ΔGe. The addition of V also interfered in the corrosion resistance of the alloy. Electrochemical measurements were carried out to evaluate the corrosion resistance alloys. With the results obtained, an increase in corrosion resistance was observed with the increase in the vanadium content in the alloy. The results of this work provide an important systematic analysis for the development and application of corrosion resistant CuAlMn SMA

Thermomechanical Behavior of CuAlMn SMA Cellular Structures Obtained by Rapid Investment Casting

Shape memory alloy (SMA) bidimensional cellular structures (CSs) have a great potential application in attenuation of vibrations due to reversible martensitic phase transformations induced by thermal or mechanical loading. This work aims to produce a thermal and mechanical characterization of CuAlMn SMA CSs produced by rapid investment casting (RIC). Structures with different unit cell geometries and thicknesses of 0.5 mm and 1 mm were manufactured by centrifugal RIC. Compression tests at different temperatures were performed on the CS to verify its thermomechanical behavior. We observed that a CS with a thickness of 0.5 mm presents greater mechanical strength and lower levels of maximum force at the end of each 5% compression cycle, ranging from approximately 1/10 to 1/3, compared to structures with a thickness of 1 mm. Among all the CS configurations, the re-entrant structure exhibited higher levels of force, with higher secant stiffness and dissipated energy. The structures resisted the application of compressive forces that varied between 125 N and 500 N for the 0.5 mm CS and between 500 N and 5500 N for the 1 mm CS. Therefore, the results showed that all CuAlMn SMA CSs produced by RIC exhibited sufficient strength to attain strain levels of up to 5% at different temperatures, and that the unit cell geometry can be used to tune the mechanical properties