Comparison of Rare Earth Refinement in 4130 and HY100

Solidification based grain refinement has gained wide interest by both researchers and industry. This method provides a route for refinement in processes where thermomechanical approaches are ineffective. Prior research into 4130 and HY100 found very different responses when rare earth additions were made. The 4130 was effectively refined while HY100 showed no response. The cause of this difference was not determined. The research presented in this paper examined heats of 4130 and HY100 with rare earth silicide or EGR additions. Characterization included macrostructure examination, mechanical testing, thermal analysis, and electron microscopy. Refinement was observed only in the treated 4130 heats and corresponded to an increase in the peritectic temperature. The HY100 heats had no changes in macrostructure or solidification reactions. Rare earth containing inclusions of similar compositions were observed in the treated 4130 and HY100 heats. These inclusions appear to be a good fit for austenite based on the 4130 data. It was proposed that the unresponsiveness of HY100 was due to the strong segregation of nickel before the peritectic in that alloy. Nickel promotes austenite, and its segregation may provide a stronger driving force for its formation than the energy barrier reduction caused by the presence of rare earth inclusions.

Mechanism of self-propagating hightemperature synthesis of AlB2‒Al2O3

The mechanism of self-propagating high-temperature synthesis (SHS) of AlB2‒Al2O3 composite powders was studied by means of a combustion front quenching method (CFQM). The results showed that combustion reaction started with the melting of B2O3 and Al particles. As the combustion reaction proceeded, the interpenetration of Al and B2O3 in melts happened. The XRD results of the product revealed the reflections of Al2O3, suggesting there had been an exchange of oxygen atoms between Al and B, and evidencing the reaction, B2O3 (l) + 2Al (l) → 2B (s) + Al2O3 (l). Under higher temperature, some of B2O3 volatilized and reacted with B forming gaseous B2O2, which deposited on the surface of Al to precipitate Al2O3 and B. Then B made available dissolved into Al melt, and reacted with the Al in melt to precipitate AlB12 particles. Finally, AlB12 transforms to AlB2 at the peritectic temperature under high cooling rate. Thus, this combustion reaction can be described by the dissolution-precipitation mechanism. In the final products, besides AlB2 and Al2O3 particles, some of Al was also detected. A model corresponding to the dissolutionprecipitation mechanism was proposed, and the ignition temperature of the combustion reaction was determined to be around 800 °C. Ill. 13. Ref. 47.

Effect of Ti-Doped on Y134 Superconductor

We investigated some properties of Y134 superconductor doped Ti superconductor. The series of samples of Y134 doped Titanium (YBa3Cu4TixO9-δ) which x=0, 0.05, 0.10, 0.15, 0.20, 0.25 were prepared by solid state reaction method with calcinations and sintering temperature at 980 °C. The porosity was reduced and the melting area were found for all Ti-doped samples. There was a little effect of Ti-doped on Tc onset but the lower of Tc offset were found that agree with the melting found on surface of sample with Ti-doped. The peritectic temperature of Y134 powder, and Y134 + 0.10Ti were on the same range about with more peak area of pure Y134 than Y134 with Ti-doping.

Film thermal stability correlation with seeding modes in the growth of YBa2Cu3O7−δcrystals

High-quality and large YBa2Cu3O7−δ(YBCO or Y123) single crystals are necessary for both fundamental studies and practical applications. The recently exploited modified melt growth (MMG) procedure realizes a high efficiency of growth and high purity of Y123. However, it was unexpectedly found that the thermal stability of the NdBa2Cu3O7−δ(Nd123) film seed applied in MMG is greatly reduced owing to a change in the liquid property. In order to solve this problem, a new top-seeding mode, buried seeding, is developed to strengthen the film thermal stability, leading to a remarkable enhancement of endurable maximum processing temperature of over 30 K in low supersaturation. Furthermore, the correlation of the thermal stability of the film seed in melt growth with the liquid property and top-seeding modes is clarified. Most importantly, the buried-seeding mode was successfully applied in this work, opening a promising pathway for the effective growth of single crystals of other REBCO (RE = Nd, Sm, Gd) oxides (possessing a higher peritectic temperature than YBCO), as well as other functional oxides.

Mushy Zone Resolidification in a Temperature Gradient in Multiphase and Multicomponent Alloys

A model for simulating mushy zone resolidification in a temperature gradient is presented. For describing macroscopic mass transport in the liquid phase in the mushy zone, an extended diffusion equation is solved numerically using the Finite Difference Method. Temperature dependent local equilibria at each position in the mushy zone are calculated using the thermodynamic software package ChemApp. The resolidification model treats multicomponent alloying systems and accounts for multiphase equilibria. Simulation results for peritectic Cu-40wt%Al and eutectic Al-5wt%Si-1wt%Mg alloys are compared with microstructures from temperature gradient annealing experiments. It is shown that the model is well suited to predict mushy zone resolidification in multicomponent and multiphase alloys. The predicted evolution of the liquid fraction is qualitatively in full agreement with the observed microstructures, including local remelting at the peritectic temperature prior to resolidification, an effect that was first predicted by the model and confirmed by the experiments.

Preparation and Characterization of the New Y257 Superconductors

The new Y257 superconductor in YBaCuO family was synthesized by standard solid state reaction. The Y257 samples were measured the critical temperature (Tc) by the four-probes method that found at 90 K. The XRD technique and FULLPROF program were used to determine the lattice parameters, space group and phase compositions. It was found that the Y257 exhibited in both of superconducting and non-superconducting phase. The Pmmm space group was fit well on superconducting phase with the lattice parameters as a=3.8108 Å, b=3.8544 Å and c=26.4967 Å. The non-superconducting phase exhibited in two space groups of Pccm (a=12.9770 Å, b=20.54780 Å and c=11.3530 Å) and Im-3m (a= 18.2104 Å, b=18.2104 Å and c=18.2104 Å). The peritectic temperature at 976.73°C was measured by differential thermal analysis.

Investigate the Properties of Y211 Doping Effect in the New Superconducting Y7Ba11Cu18Oy Compound

The new superconductors of Y-based compound, Y7Ba11Cu18Oy(Y7-11-18), has been discovered by solid state reaction with the different ratios of raw materials. All obtained samples were analyzed and characterized by XRD and the FULLPROF program. The lattice parameters of Y7-11-18 were a=3.8268 Å, b=3.8810 Å and c= 69.8794 Å. The Y7-11-18 showed the sharp transition curve of resistivity (ρ) at the critical temperature (Tc) =94 K. The doping of Y2BaCuO5 (Y211) showed that the higher Y211, the lower Tc and c lattice parameter. The SEM and EDX micrographs showed the grain size about 1-5 μm and without impurities. The DTA analysis resulted the decreasing of peritectic temperature from 962.74 °C by the higher Y211 contents.

The Preparation and Characterization of Y145 Superconductor

In this research, we synthesized and characterized the physical properties of YBa2Cu3Ox (Y123) and YBa4Cu5Ox (Y145) superconductors by solid state reaction and melt process. The raw materials Y2O3, BaCO3 and CuO were mixed, ground and react in the air atmosphere at 950 °C, at 980 °C for solid state reaction and melt process, respectively. The samples obtained were characterized by the resistivity measurement, SEM, EDX, XRD and DTA. It was found that the critical temperature onset of Y145 is 94 K and 96 K for solid state reaction and melt process, respectively. The samples were inhomogeneous with no impurity. The crystal structures was orthorhombic which a = 3.80446 Å, b = 3.86474 Å and c = 19.37104 Å for Y145 solid state reaction and a = 3.80180 Å, b = 3.86483 Å and c = 19.38194 Å for melt process. The peritectic temperature of Y145 is 1018 °C.

Hydrocarbon fluid inclusions in the Argo salt, offshore Canadian Atlantic margin

Fluid inclusions hosted in rock salt from the Triassic Argo Formation in the Canadian Atlantic continental margin were studied to investigate the nature and origin of petroleum fluids in them. Inclusions were studied in two wells: Glooscap-C63 and Weymouth-A45. The pillow-shaped salt body intersected by the Glooscap-C63 well is autochthonous, and the salt is transparent and colorless compared with that in the allochthonous, canopy–diaper-shaped body cut by the Weymouth-A45 well which is translucent and buff-colored. Aqueous (AFI), petroleum (PFI), and heterogeneously trapped, mixed petroleum – aqueous (MFI) fluid inclusions were identified using transmitted and fluorescent microscopy, and representative samples were analyzed microthermometrically. Petroleum-bearing fluid inclusions (PFI and MFI) are more common and contain more concentrated petroleum phases in the allochthonous salts of Weymouth-A45 well. Based on microthermometric studies, the AFI and MFI in Glooscap-C63 salt mostly belong to NaCl–H2O and NaCl–H2O–petroleum systems, respectively; in contrast, those of Weymouth-A45 belong to NaCl–MgCl2–H2O and (or) NaCl–CaCl2–H2O and NaCl–MgCl2–H2O–petroleum and (or) NaCl–CaCl2–H2O–petroleum systems, respectively. Each of the AFI, PFI, and MFI types consists of different phases. The medians of Tf (freezing temperature), Tim (initial melting temperature), Te (Eutectic temperature), Tm (final melting (peritectic) temperature), and Th (homogenization temperature) in the AFI and MFI in the salts of Glooscap-C63 well are (−82, −75 °C), (−39, −38 °C), (−25, −24 °C), (−1.8, −3 °C), and (291, 287 °C), respectively. The corresponding medians for the Weymouth-A45 well are (−71, −78 °C), (−52, −52 °C), (−37, −38 °C), (−2.7, −3 °C), and (122, 20 °C), respectively. The median Th of PFI in Glooscap-C63 and Weymouth-A45 salts are 79 and 23 °C, respectively. The most probable source rocks for the petroleum are the shales of the Late Triassic – Early Jurassic Eurydice Formation which is widely distributed at depth underlying the Argo salt.