Microstructure characterization and hardness of Al-Cu-Mn eutectic alloy

The composition of Al-Cu-Mn ternary eutectic alloy was chosen to be Al-32.5 wt.%Cu-0.6 wt.%Mn to the Al2 Cu and Al12 Cu Mn2 solid phases within an aluminum matrix(α-Al) from its melt. The Al-32.5 wt.%Cu-0.6 wt.%Mn alloy was directionally solidified at a constant temperature gradient(G=8.1 K·mm^(-1)) with different growth rates, 8.4 to 166.2 μm·s^(-1),by using a Bridgman-type furnace. The eutectic temperature(the melting point) of 547.85 °C for the Al-32.5 wt.%Cu-0.6 wt.%Mn alloy was obtained from the DTA curve of the temperature difference between the test sample and the inert reference sample versus temperature or time. The lamellar spacings(λ) were measured from transverse sections of the samples. The dependencies of lamellar spacings(λAl-Al2 Cu) and microhardness on growth rates were obtained as, λ_(Al-Al2Cu)=3.02 V^(-0.36), HV=153.2(V)^(0.035), HV=170.6(λ)^(-0.09) and HV=144.3+0.82(λ_(AlAl2 Cu))^(-0.50), HV=149.9+53.48 V^(0.25), respectively, for the Al-Cu-Mn eutectic alloy. The bulk growth rates were determined as λ~2_(Al-Al2 Cu)·V = 25.38 μm^3·s^(-1) by using the measured values of λ_(Al-Al2 Cu) and V. A comparison of present results was also made with the previous similar experimental results.

Lattice Dynamics and Electronic Properties of Heusler Alloys Li_(2)AlX(X=Ga,In):A Comparison Study

The lattice parameters,bulk modulus,rst derivative of the bulk modulus,electronic band structures,phonon dispersion curves and phonon density of states calculations for Li_(2)AlGa and Li_(2)AlIn Heusler alloys are performed and compared in this study using density functional theory within the generalized gradient approximation.Computed lattice parameters display a good agreement with the literature.Obtained electronic band structures of both Heusler alloys show that they are in semi-metallic structure.Phonon dispersion curves and the phonon density of states graphs are also obtained in order to study the lattice dynamics of these Heusler alloys.It is noticed that Li_(2)AlGa and Li_(2)AlIn Heusler alloys are dynamically stable in the ground state.

Photometric Investigation of Contact Binary DY Cet Based on TESS Data

We present a photometric analysis of the Transiting Exoplanet Survey Satellite(TESS)light curve of contact binary system DY Cet and the behavior of its orbital period variation.The light curve and published radial velocity data analysis was performed using the Wilson-Devinney code.As a result of simultaneous analysis of the light curve with radial velocity data,the masses and radii of the system’s components were determined as M_(1)=1.55±0.02 M_(⊙),M_(2)=0.55±0.01 M_(⊙) and R_(1)=1.51±0.02 R_(⊙),R_(2)=0.95±0.02 R_(⊙),respectively.The degree of contact(f)and mass ratio(q)of the system were determined as 23%and 0.355±0.012,respectively.Orbital period analysis of DY Cet was conducted for the first time in this study.It was observed that the orbital period has a sinusoidal change with decreasing parabola.To explain the orbital period change,mass transfer between components is proposed with the assumption of conservative mass,and the transfer rate was calculated to be dM/dt=1.1×10^(-7) M_(⊙)yr^(-1).A possible third component is suggested for explaining the sinusoidal change,and the mass of the unseen component was determined as 0.13 M_(⊙).The age of the DY Cet system was estimated as 3.77 Gyr.

Investigation of Erosion Corrosion Caused by Drinking Water in the Faucet with Computational Fluid Dynamics

In this study,the reason for erosion-corrosion of drinking or mains water in the faucet was investigated by computational fluid dynamics.Pipes used in homes,the service sector,and industry are responsible for transporting different types of fluids from one place to another.Considering the faucet design,the SolidWorks program was used for 3D studies.In-faucet flow analyses were performed using Ansys Fluent,a computational fluid dynamics program based on the finite volume method.In the analyses,lime particles were chosen.At the end of the analysis,the amount of erosion in the faucet was obtained.

Determination of the inner forms of hollow blocks containing phase-changing material for different climate regions

Hollow blocks are used widely in buildings for their lightweight construction and high thermal resistance charac-teristics.When used with a phase change material(PCM),these blocks can reduce the heating and cooling loads of buildings compared to conventional hollow blocks.However,it is essential that the block inner forms and PCMs should be selected based on climate conditions.In this study,hollow blocks containing PCM in different climate types are thermally analysed.In the first step,ten different formed blocks are thermally analysed.In these blocks,the effects of hollow ratio(HR),inner form,and the number of cavities on heat flux and temperature distribution are investigated.The inner form of the hollow block with the least heat flux is determined in this step.The second step consists of optimization for the PCM melting temperature and layer thickness for the different provinces.The optimization results are evaluated on a building in terms of primary energy consumption and global costs.The best performing locations of the PCMs within the block are defined for all provinces in the last step.The results of the study are discussed in terms of the block surface temperatures and liquid fraction.The best PCM locations are found close to the block’s centerline in hot and warm climates and close to the indoor side in cold climates.