Phase transformation of the Ti-5553 titanium alloy subjected to rapid heating

Journal of Materials Science - The α?→?β phase transformation upon heating in the Ti-5553 alloy with lamellar-nodular bimodal microstructure was tracked in situ with...     

Experimental study of phase transformations in 3003 aluminium alloys during heating by in situ high energy X-ray synchrotron radiation

This paper aims to study microstructural evolutions in the 3003 aluminium alloys during the heating part of the homogenization treatment from the as-cast state. After solidification, both the solid solution and primary precipitates are far from equilibrium. During a subsequent heating, an eutectoid transformation of the primary eutectic particles and a fine precipitation of dispersoids occur. The evolution of the precipitation amounts are obtained by high energy synchrotron radiation diffraction and microstructural observations (TEM and SEM) combined with image analysis. The analysis of these different results lead to the volume fraction evolutions of dispersoids and primary particles with temperature. Moreover, the different evolutions are compared to in situ electrical resistivity leading to propose the main causes of the variations observed.     

Interaction Between Eutectic Intermetallic Particles and Dispersoids in the 3003 Aluminum Alloy During Homogenization Treatments

The transformation of primary eutectic Al₆(Mn,Fe) intermetallics into α-Al(Mn,Fe)Si and the precipitation of dispersoids were studied in the commercial in the form of 3003 series cast aluminum alloys, mainly under isothermal conditions between 673 K and 873 K (400 °C and 600 °C). After solidification, both the solid solution and the primary eutectic intermetallics were far from equilibrium. During further heat treatment, the precipitation of fine dispersoids and eutectoid transformation of the primary eutectic particles occurred simultaneously. Having characterized these evolutions under industrial homogenization conditions, the evolution of the microstructure (in terms of its nature, and the quantity, size, and chemical composition of the phases) was characterized during isothermal heat treatment, using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations, quantitative image analysis, and transmission electron microscopy–energy-dispersive spectroscopy (TEM-EDS). The experimental results are analyzed, and changes in chemical composition are discussed and compared with the calculated equilibrium compositions. It is shown that (1) the chemical composition of eutectic intermetallics evolves and tends toward an equilibrium composition; (2) during precipitation, the chemical composition of dispersoids is constant, and close to the expected equilibrium composition when the initial mean composition of the solidification cell is taken into account; (3) after the formation of dispersoids, the quantity of α-Al(Mn,Fe)Si formed from the initial eutectic intermetallics increased, with the kinetics being controlled by long-range manganese diffusion; and (4) the latter evolution is associated with the dissolution of dispersoids located close to eutectic intermetallics and contributes to the formation of a dispersoid-free zone (DFZ).     

On the use of wind energy to power reverse osmosis desalination plant: A case study from Ténès (Algeria)

The aim of this study was to provide a detailed analysis of wind energy resources for seawater reverse osmosis desalination (SWRO), in a case study region of Ténès Algeria, by using commercial Wasp software. An economic analysis of the environmental benefits was also done using RETScreen software to give details about financial investment hazards and CO₂ emissions reduction. An energy yield and economical analysis was performed of a hypothetical wind farm consisting of 5 wind turbines of type Bonus 2 MW. It was found that wind energy can successfully power a SWRO desalination plant in the case study region.     

σ-Phase Formation in Super Austenitic Stainless Steel During Directional Solidification and Subsequent Phase Transformations

Metallurgical and Materials Transactions A - The solidification path and the σ-phase precipitation mechanism in the S31254 (UNS designation) steel are investigated thanks to Quenching during...     

Properties of nanocrystalline and nanocomposite WxZr1−x thin films deposited by co-sputtering

W_xZr_1?x thin films were deposited at room temperature on glass substrates by co-sputtering tungsten and zirconium targets in argon. The composition was found in the range 0 ≤ x ≤ 0.81. The grain size deduced from X-ray diffraction analysis ranged from 1.3 nm to 16 nm depending on the composition. The events in the resistivity, optical reflectivity and thickness evolutions were correlated with the X-ray diffraction analysis. Depending on the composition, the local organization can be attributed to a nanocrystalline solid solution of W in Zr, to a nanocomposite structure involving ZrW₂ nanograins embedded in an amorphous matrix, to ZrW₂ Laves phase nanograins and to a nanocrystalline solid solution of Zr in W. For 0 < x ≤ 0.72, the equivalent grain size is very small (less than 2 nm) and the evolution of the resistivity can be fitted by the estimated volume of the material perturbed by the grain boundaries.