Defect and Diffusion Forum Vol. 330

Abstract: The Volume Diffusion of Homovalent Atomic Probes (APs) from the VB Group of the Periodic Ta-Ble of Elements (PTE) – V and Nb in W Single Crystals Has Been Studied by Using the Method of Secondary Ion Mass Spectrometry (SIMS). the Parameters of the Arrhenius Dependence of the Coefficients DV of Vanadium Volume Diffusion in W Have Been Measured: (D0)V = (1.3  0.4) X 10-4 M2s-1 and QV = (564 ± 6) Kj/mol. the Parameters (D0,Q)Nb of the Bulk Diffusion of Nb Aps in W Have Been Estimated with the Help of Several Measured Coefficients Dnb and the Empirical Correlation [1,2]: (D = DWW)(Tm)W: the Diffusion Coefficients of Substitutional Non-Magnetic 5d-Aps Coincide with the Self-Diffusion Coefficients in W at its Melting Point (Tm)W. the Enthalpies Qnb,Ta of the Bulk Diffusion of Non-Magnetic (nm) Homovalent Aps from the VB Group of PTE – Nb and Ta [3] Also Coincide with the Relaxation Volumes vacVBAPs of Complexes “vacancies-VB Aps” in the W Lattice. Electron Contributions (EDN)vacVBAPs to the Energies Evacvbaps of Interaction of Point Defects in Complexes “vacancies- VB Nm- Aps” Are Lower than in Complexes “vacancies-IVB Nm- Aps” [4]. the Dependence of {EDN(n)}vacVBAPs the Electron Contributions (EDN)vacVBAPs on the Difference of N Numbers of Periods of PTE the Deviation of Contributions (EDN)vacVAPs for Vanadium Aps to En-Ergies Evacvaps of their Interaction in Complexes “vacancy-VAP” Has Been Determined. this Devi-Ation Is Conditioned by the Contribution of the Exchange Energy (Eexch)VAP of Vanadium to the En-Ergy Evacvaps of the Point-Defect Interactions in the Complex “vacancy-VAP”.

Abstract: The Electrical Resistivity and a Mechanical Property (hardness) of some 5xxx Aluminum Alloys Were Investigated. the Samples Were Exposed to a Type of Plastic Deformation (compression) to Nearly40% Deformation; the Resistivity and Vickers Hardness Being Measured for Every Degree of Deformation. the Investigated Alloys Gave a Good Response to the above Two Techniques, and the Results Were Consistent with each other.

Abstract: Defects are central to any understanding of material characteristics. They determine a host of material properties, including strength, ductility, resistivity and opacity. Positron annihilation spectroscopy (PAS) is a well-established high-sensitivity technique for detecting defects in solids. In this work, we study the influence of plastic deformation on the properties of 5754(AlMg3) aluminum alloy.

Abstract: The methods of Mössbauer spectroscopy and X-ray diffraction analysis have been used to study the processes of a solid-phase alloying of the iron alloys with a bcc lattice by nitrogen that occur upon ball-mill mechanical activation in the presence of chromium nitrides. It is shown that a deformation-induced dissolution of chromium nitrides in the matrix of pure iron and in that of the alloys Fe–3Al and Fe–6V results in the formation of the substitutional chromium and interstitial nitrogen bcc solid solutions. An additional alloying of iron with aluminum or vanadium under the deformation dissolution of nitrides leads to the escape of aluminum and vanadium from the matrix and to a decrease in the nitrogen content characteristic of the interstitial solid solution proper due to the strong chemical bonding of alloying elements with nitrogen. The subsequent annealing leads to the decomposition of already formed solid solutions with the formation of aluminum, vanadium, and chromium nitrides of extreme dispersion.

Abstract: Tronoh silica sand was ground to nanoparticles using a ball mill and it was observed that the milling process increased the percentage purity of silica in silica sand. The size of the nanoparticles of silica sand was verified by using a ZetaSizer nanoparticles analyzer and FESEM analysis. The silica sand nanoparticles were used to develop and study the characterization and properties of metal, ceramic and polymer based composites. The powder metallurgy and powder processing techniques were used to develop MMC and CMC composites. Compression moulding was used to develop polymer matrix (HDPE) composites. An increased hardness in the case of MMC and CMC was observed. The tensile strength and flexural strength exhibited an increasing trend in the case of PMC with up to 15wt.% of silica sand nanoparticles.

Abstract: The ornamental granite stone-processing industries of Tamilnadu state produce tons of fine powder wastes during sawing and polishing. It is a non-biodegradable waste that can be easily inhaled by human being and animals and is also harmful to the environment. The main objective of this study is to investigate experimentally the suitability of granite powder (GP) waste as a substitute material for fine/natural aggregate in concrete production. The physical and chemical characterization of the GP waste was also addressed. The experimental parameter was the percentage of granite powder substitution. The cubes and cylinders were prepared using 0%, 5%, 10%, 15%, 20% and 25% of fine/natural aggregate substituted by GP waste. To understand fully the influence of GP waste on the behavior of concrete, several tests such as density, slump cone, split tensile strength, flexural strength; ultra sonic pulse velocity (UPV) and compressive strength tests were performed. The Young’s modulus of elasticity of the concrete was also determined. The GP waste exhibited a very high specific surface value of about 340kg/m2 and chemical analysis results showed that the examined material contains about 77% of silica (SiO2). Experimental results revealed that the rough texture and high specific area of the GP waste significantly decreased the workability of the concrete especially for the substitution level of 20% and 25%. The obtained test results show that the substitution of GP waste up to 15% does not affect the mechanical and fresh concrete properties of the concrete and it was recommended that the replacement of natural sand by GP waste up to 15% of any formulation would be favorable for concrete making.

Abstract: The graphs for variation of vacancy formation energy ( ) with r_c of Ashcroft's empty core model potential for different exchange and correlation functions are shown for six bcc metals, viz. Li, Na, K, Rb, Cs and Ba. Fitted value of for Li, Na, K, Rb, Cs and Ba are respectively 1.343, 1.694, 2.205, 2.384, 2.962 and 2.337 atomic unit (AU).