International Journal of Microstructure and Materials Properties (14 papers in press)
Asymmetric Gated Ge-Si0.7Ge0.3 nHTFET and pHTFET for Steep Subthreshold Characteristics
by Suman Lata Tripathi, Sobhit Saxena
Abstract: The miniaturisation of transistors imposes thermal limits on MOSFET structures due to increase in leakage current and static power consumption per unit area of chip below 20 nm technology node. Tunnel FET has potential to reduce static power consumption to design below 20 nm technology within thermal limits thus increases the scope of future scaling trends. A new asymmetric Ge-Si0.7Ge0.3 hetero-junction tunnel FET (HTFET) is proposed with different oxide thickness from source and drain side. The
asymmetric Ge-Si0.7Ge0.3 HTFET has steep subthreshold characteristic, low DIBL with high ION/IOFF current ratio for operating voltage less than 1V. The proposed design can be fabricated easily due to the similar lattice structure of Ge and Si. The ION/IOFF current ratio greater than 108 is achieved for gate length of 15 nm in nHTFET having Pt/HfO2 as gate contact and oxide material. The lowering of parasitic BJT effect in OFF state condition is also achieved in the same.
Keywords: band to band tunnelling; BTBT; drain induced barrier lowering; DIBL; subthershold slope; SS; hetero-junction; narrow band gap material.
Micro hardness and corrosion properties of A390alloy + x vol. % Zirconium dioxide (ZrO2) composites processed by P/M method
by Karthikeyan S, M. Subramanian, Ashoke Ghosh, M. Prashanth, R. Karunanithi
Abstract: A390+X vol. %ZrO2 (X=5, 10, 15) composites have been fabricated through P/M technique. The mixed aluminum alloy and zirconium oxide powders were cold compacted at 200MPa and sintered at 580
Keywords: A390 alloy; Zirconium Oxide; Corrosion; Vickers micro hardness; Powder Metallurgy.
Comparison of texture evolution in low carbon steel fabricated by plane strain and multi-directional forging of the martensite starting structure
by Mahdi Saalari
Abstract: It has been clarified that deformation and annealing of martensite starting structure can produce ultrafine grained structure in low carbon steel. This study aims to investigate the texture evolution and mechanical properties of samples with martensite structure deformed by two different forging processes. The martensitic steel samples were forged by plane strain compression and multi-directional forging up to the same true strain of 2. All samples were then annealed at 450 and 550
Keywords: texture evolution; martensite treatment; multi-directional forging; plane strain compression; low carbon steel; mechanical properties.
Structural, Thermal and Electrical Properties of Ionic Conductors (AgPO3)1-x(Ag2SO4)x Glass Systems
by Atif Alkhazali, Morad Etier, Mohammad Aljarrah, Hesham Al-Momani, Fathy Salman
Abstract: This study aims to investigate the effect of temperature and frequency on the ac conductivity of ion conducting glasses systems of (AgPO3)1-x(Ag2SO4)x , where x = 0.00, 0.10, 0.15, 0.20 and 0.25. Structural characterization was examined in different samples using different techniques. At lower frequency range, the frequency dependence of the total conductivity was nearly constant and then followed a power relation as frequency and temperature increased. The observed values of the exponent S were somehow frequency-dependent and decreased with increasing temperature from 1.3 to 0.2 for the composition when x = 0.15. The cutoff frequency from dc to the dispersive region, ?c, increased with temperature. In addition, ?c values were within the same range as other values. Total conductivity ?tot(?) was found to be thermally activated of the Arrhenius type.
Keywords: ionic conductivity; impedance spectroscopy; glass synthesis.
Vegetable oil quenchants: a review
by Rosa Lucia Simencio Otero, Lemmy Meekisho, Lauralice De Campos Franceschini Canale, George Edward Totten
Abstract: For thousands of years, vegetable oils have been used as cooling media to heat treat metals. However, the motivation for employing quenchants formulated with biodegradable, non-toxic and renewable base stocks has seen significant increase due to the environmental appeal to replace petroleum based quenchants. This paper presents an overview of the main aspects and characteristics of vegetable oils that directly influence their commercial application such as structure, classification, biodegradability and toxicity, quenching properties, oxidation and inhibition, and wetting. Further, some applications of vegetable oils as quenchants will be discussed here.
Keywords: quenching; heat treating; heat transfer; vegetable oil; triglycerides; hardening; quenchants.
Surface morphology analysis of AISI-D3 tool steel using rotary tool electric discharge machining process
by Anand Prakash Dwivedi, Sounak Kumar Choudhury
Abstract: Electric discharge machining (EDM) is one of the most prominent machining processes, which is used across the world for machining and creating intricate shapes in very hard-to-cut electrically conducting materials. This comprehensive study aims to investigate the surface modification and characterisation of thin AISI-D3 tool steel sheets and provides thorough information about the material characteristics, which are quite vital from the design and reliability point of view. The analysis shows that the average improvement in the final surface finish of the machined surface is close to 12%. In addition, the energy dispersive spectroscopy (EDS) images confirm the presence of 2.1% copper and 25.22% of carbon on the workpiece surface, showing the tool material transfer at the workpiece surface. Moreover, the scanning electron microscope (SEM) images confirm the presence of a thinner recast layer, fewer micro-cracks and very less embedding of tool material on the workpiece surface as compared to the stationary tool process.
Keywords: EDM; electric discharge machining; EDS; energy dispersive spectroscopy; SEM; scanning electron microscope; micro-cracks; recast layer.
Determination of temperature-dependent Young's modulus of bulk metallic glass
by Suresh Kaluvan, Haifeng Zhang, Sanghita Mridha, Sundeep Mukherjee
Abstract: Bulk metallic glasses (BMGs) are fully amorphous multi-component alloys with homogeneous and isotropic structure down to the atomic scale. Some attractive attributes of BMGs include high strength and hardness as well as excellent corrosion and wear resistance. The research goal of this paper is to determine the mechanical properties at elevated temperatures. To accomplish this goal, we have used two methods in this paper to determine the Young's modulus of a BMGs, Zr41.2Ti13.8Cu12.5Ni10Be22.5 at elevated temperatures: sonic resonance method and nanoindentation. In the sonic resonance method, the system was designed using a laser displacement sensor to detect the sonic vibration produced by a speaker on the specimen in high-temperature furnace. The Young'ss modulus was found to reduce from 100 GPa (350°C) to 94 GPa (50°C). In the nanoindentation method, modulus was determined from the unloading curve and found to be in the same range as measurements from sonic resonance technique.
Keywords: Young's modulus; elevated temperature; sonic resonance; metallic glass.
Study of crystal-amorphous phase transition and morphologies of metal nanoparticle Fe under annealing
by Pham Huu Kien
Abstract: The present work investigates the crystal-amorphous phase transition and morphologies of metal nanoparticles Fe (NPs) using means of molecular dynamics (MD) simulation. Tracing the number of crystal atoms and the analysis of radial distribution functions, we found that the amorphous Fe NP is transformed into bcc crystal one when it was annealed for long times at 900 K. At the early stage of the annealing, small nuclei form in different places of NP and dissolve for short times. After long times some nuclei form and gather nearby which creates the stable clusters in the core of NP and to spread into the surface of NP. Based on the mean potential energy per atom analysis and MD data visualisation technique, the effect of B atoms that prevent the growth of crystallisation as well as the different morphologies of Fe and FeB NPs have been investigated in detail.
Keywords: phase transition; annealing; morphologies; crystal; amorphous; liquid; crystal atom; cluster; crystal grain; amorphous phases.
Analysis of influence of ultra-hydrophilicity of oxidation titanium surface on blood compatibility based on density functional theory
by Qiongjian Huang
Abstract: Based on the density functional theory, it adopts the first-principles method to calculate the ultra-hydrophilicity of oxidation titanium surface under different oxygen vacancy concentrations. The calculation results show that under the practically feasible oxygen vacancy concentration range, with the increase of the oxygen vacancy concentration, the ultra-hydrophilicity of oxidation titanium surface is increased, and the semiconductor type of the oxidation titanium is transformed from p type to n type. When the oxidation titanium surface is in contact with blood, the n-type semiconductor and the features of the electron state occupying the bottom of conduction band of the oxidation titanium surface can suppress the transfer of charge from the fibrinogen in the blood to the oxidation titanium surface so to suppress the aggregation and activation of blood platelet, thus improve the ultra-hydrophilicity of oxidation titanium surface on blood compatibility.
Keywords: oxidation titanium; oxygen vacancy; blood compatibility; electronic structure.
Structural, optical and electrical properties of CuBiS2 thin films deposited by spray pyrolysis at different deposition times
by A.M. Mansour, I.M. El Radaf
Abstract: Reproducible and good quality copper bismuth sulphide (CuBiS2) thin layer were situated on preheated glassy slide substrates made implementing the spraying pyrolysis approach at distinctive times of spraying 15, 30, 45, and 60 min with a fixed substrate temperature 400°C. The effect of spray time on the structural, morphology, optical and electrical benefits of the CuBiS2 thin films produced by spray pyrolysis methodology were studied. The structure was studied by XRD methodology. The surface texture of the produced films was considered by SEM. The optical benefits of the CuBiS2 films were inquired working with the spectrophotometric method in which the optical transmittance and reflectance beyond a wavelength range 200-2500 nm were measured. The d.c. conductivity was studied at different temperatures for all the prepared CuBiS2 thin films.
Keywords: copper bismuth sulphide; spray pyrolysis; optical; band gap; electrical.
Modelling and simulation of a bending process for S34MnV steel
by Zhiqiang Hu, Kaikun Wang, Yan Yang
Abstract: To investigate the hot deformation behaviour of S34MnV steel, hot compression tests in different deformation conditions were done. According to the experimental data, a constitutive equation was established and a mathematical model for dynamic recrystallisation was established to predict the volume fraction of dynamic recrystallisation. To reveal the plastic deformation, the bending process for a large S34MnV marine crank was simulated by Deform-3D. The stress and strain field of the bending process was obtained and analysed based on the simulation. Finally, to study the effect of the bending process on the crank, a bending process of a crank produced with a hydropress in the factory was studied. The microstructure and mechanical properties in three different positions of the bending crank were analysed. It was concluded that the bending process would reduce the uniformity of the microstructure and mechanical properties, owing to the nonuniformity of the deformation.
Keywords: hot deformation behaviour; modelling and simulation; bending process.
Micro-structural and interfacial transition zone investigation on oil palm shell lightweight concrete
by Muthumani Krishnamurthy, Swamy Nadh Vandanapu
Abstract: Oil palm shell (OPS) aggregates can be used as a replacement of coarse aggregate in concrete to produce lightweight concrete. OPS is found to absorb more water compared to normal aggregate. Hence, surface treatment is carried out on OPS and the effect of water cement ratio on strength of concrete is investigated. This paper presents X-ray diffraction analysis carried out for treated and non-treated OPS (NTOPS) aggregate to find the mineralogical characteristics. Microstructural analysis and interfacial transition zone is investigated for treated and NTOPS using digital image processing or digital microscope. The results of investigation is compared with conventional concrete.
Keywords: micro-structure; interfacial transition zone; treated oil palm shell; non-treated oil palm shell; lightweight concrete; conventional concrete; surface treatment.
Effect of deposition temperature on structural, optical and electrical properties of chemically deposited thermochromic Cu2HgI4 thin films
by A.M. Mansour, I.M. El Radaf, G.M. Mahmoud
Abstract: Copper mercury tetraiodide thin films were grown by the chemical bath deposition technique at different deposition temperatures varying from 300 K to 345 K. The structural properties of the prepared Cu2HgI4 thin films show that the Cu2HgI4 films have a polycrystalline nature. The compositional analysis confirmed the nearly stoichiometric structure of the deposited Cu2HgI4 thin films. Homogeneous and regular surface morphology, including of circular-shaped grains with a size range from 31 to 46 nm, was revealed. Thermal stability and phase transition were studied by means of thermogravimetric analysis (TGA) and differential thermal analysis (DSC), respectively. The effects of deposition temperature on the optical properties and D.C. electrical conductivity of the Cu2HgI4 films have been studied. The films were found to have an indirect optical energy gap of values increases with increasing substrate temperature. The electrical conductivity increases with increasing temperature according to grain boundary trapping model.
Keywords: copper mercury tetraiodide; differential thermal analysis; TGA; thermogravimetric analysis; optical; electrical conductivity.
Strength and microstructural characteristics evaluation of a fibre reinforced fine grained soil using Taguchi technique
by Amit Kumar, D.K. Soni
Abstract: The viability of Taguchi technique to optimise the unconfined compressive strength of polypropylene fibre (PPF) reinforced cohesive soil has been investigated in this paper. Dominating factors for UCS optimisation have also been reported. Eggshell powder and sodium chloride were used to treat the soil and 7, 14 and 21 days cured specimens were tested. The samples were prepared by design of experiments produced by Taguchi technique those arranged in orthogonal arrays. Experimental results were analysed by performing analysis of variance. Finally, optimised conditions were experimentally verified. Scanning electron microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) results were also studied to explore the microstructural changes and elemental analysis of subjected soil. Overall the study focuses on the potential of the additives to strengthen the weak soil and Taguchi technique for engineering problems. Results obtained from this study might be used for pavement design and ground improvement during foundation works.
Keywords: UCS; unconfined compressive strength; microstructural analysis; Taguchi; optimisation; eggshell powder; sodium chloride; polypropylene; fibre; cementitious compounds.