bluuebunny/crossref_metadata_2025 huggingface dataset:
Aluminum Nanocomposites via Gas Assisted Processing
Authors: Borgonovo Cecilia , Apelian Diran
Published: June 2011

Aluminum nitride (AlN) possesses superior thermal and electrical properties and is an ideal candidate for high-temperature, as well as for packaging and optoelectronic applications. Aluminum based composites reinforced with AlN have been manufactured via an in situ gas-assisted process, where nitrogen gas is injected in the molten aluminum at 1273-1323 K. The process is carried out in an inert atmosphere in order to avoid oxygen contamination. Addition of Mg lowered the oxygen content in the melt by forming MgO and thus favoring the nitridation reaction. The reinforcement phase has been detected throughout the casting in two morphologies: pockets of powders and embedded in the microstructure. Particle size formed in the matrix varied from 1- 3 µm to sub-micron scale.
Texture Development of Mg AZ80 after Cyclic Loading at 80% Yield Stress
Authors: Brokmeier Heinz Günter , Jiang Miao , Maawad Emad , Schwebke Bernd , Lippmann Thomas
Published: June 2011

In situ experiments with a 20kN loading device were carried out at the high energy beam line Harwi-II at Hasylab/Desy-Hamburg/Germany. Main goals were firstly to investigate lattice dependant strain development in the elastic as well as in the plastic region and secondly to perform cyclic loading for strain and texture development. Due to the high energy of about 100keV the synchrotron beam has a high penetration power. Moreover, measurements were comparably fast. The test sample was rectangular extruded Mg AZ80. According to the bar extrusion process, the Mg AZ80 sample has the typical texture with two ideal fibre components, <100> parallel RD and <0001> parallel ND, and an ideal texture component {0001}<100>. Tensile samples were cut with loading direction parallel to transfers direction. The sample diameter of round tensile samples was 4mm. Stress strain curves were carried out ex situ to get an overview of the materials behaviour and in situ to get strain dependant lattice values for at least 6 Mg reflections. The cyclic loading was carried out with a maximum load of about 80% of the yield stress so that one stays always in elastic region. Nevertheless, after 3800 cycles a texture change of the quantitative texture was obtained. Existing texture components are stable but the volume fractions of the three texture components change and additionally a new but weak texture component is growing.
The Relation between Shear Banding, Microstructure and Mechanical Properties in Mg and Mg-Y Alloys
Authors: Sandlöbes Stefanie , Schestakow Igor , Yi Sang Bong , Zaefferer Stefan , Chen Jing Qui , Friák Martin , Neugebauer Jörg , Raabe Dierk
Published: June 2011

The formation of deformation-induced shear bands plays an important role for the room temperature deformation of both, Mg and Mg-Y alloys, but the formation and structure of shear bands is distinctively different in the two materials. Due to limited deformation modes in pure Mg, the strain is localized in few shear bands leading to an early failure of the material during cold deformation. Contrarily, Mg-RE (RE: rare earth) alloys exhibit a high density of homogeneously distributed local shear bands during deformation at room temperature. A study of the microstructure of the shear bands by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) at different strains was performed. These investigations give insight into the formation of shear bands and their effects on the mechanical behaviour of pure Mg and Mg-3Y. Since in pure Mg mainly extension twinning and basal  dislocation slip are active, high stress fields at grain resp. twin boundaries in shear bands effect fast growth of the shear bands. In Mg-RE alloys additionally contraction and secondary twinning and pyramidal  dislocation slip are active leading to the formation of microscopic shear bands which are limited to the boundary between two grains. The effects of shear bands on the mechanical behaviour of pure Mg and Mg-RE alloys are discussed with respect to their formation and growth.
Liquid Atomic Structure and Viscosity of Al-Si Alloys with and without Sr
Authors: Jeyakumar Manickaraj , Prakash Srirangam VS , Shankar Sumanth
Published: June 2011

The liquid structure of Al-Si hypoeutectic binary alloys with and without the addition of 0.04 wt.% Sr was characterized by diffraction experiments using a high energy X-Ray (Synchrotron) beam source. The diffraction data for all the alloys were obtained at various melt temperatures. Reverse Monte Carlo (RMC) analysis was carried out using the diffraction experimental data to quantify the partial pair distribution function (PPDF). Further, the partial pair distribution function and the liquid atomic structure information were used in a semi empirical model to evaluate the viscosity of these liquid alloys at various temperatures.
Distribution of the Quality Index in AlSiMg Castings Produced by Different Processes: Reality vs Prediction
Authors: Chiesa Franco , Giguère Nicolas , Duchesne Bernard
Published: June 2011

The Quality Index is a useful tool allowing to assess the metallurgical quality of aluminium AlSiMg foundry alloys (AlSi7Mg03/AlSi7Mg06, or A356/357 in North America). Its value, calculated from the ultimate tensile strength and elongation, increases with the metallurgical quality of the casting, i.e. with finer dendrites, lower microporosity, lower iron content and cleaner metal. This Quality Index does not depend on the degree of temper applied during the heat treatment (aging time and temperature). This paper will briefly explain how solidification modeling can provide the local value of the Quality Index, via the secondary dendrite arm spacing and level of microporisity calculated from the predicted values of the local solidification time and solidus velocity. The validity of the predictions has been assessed against the properties of tensile specimens excised from parts of different geometries produced by a variety of casting processes, as reported in the literature. The case study of a race car bell housing poured by two processes, namely gravity sand casting (GSC) and low pressure die casting (LPDC, or LPPM for Low Pressure Permanent Mold in North America), will be the focus of the present paper. The Quality Index has been measured and predicted at 3 locations in the castings after a T6 temper was applied which resulted in a minimum elongation of 5% for both the GDC and LPDC bell housings. Metallographic examination and image analysis allowed to quantify the superior metallurgical quality of the LPDC housings when compared to their GDC competitors.
Studies and Researches Concerning the Presence of Iron in Secondary Aluminium Meltings and Valorification of Some Aluminium Waste
Authors: Butnariu Ilie , Butnariu D. , Butnariu I.
Published: June 2011

Present in the metallurgical industry one of the most frequently problem is the presence of Fe and his compound in secondary aluminum melting. This problem appears when using chip inadequate technologies. This work makes a survey on the problems which can appear because of the presence of Fe and his compound in aluminum. Two systems, Al-Si and Al-Si-Li, are analyzed, by taking into consideration metallographies, as well as the systems mechanical properties. The end presents metallographic evidence of the problems which Fe and his compound can cause in secondary aluminum meltings.
Development of Advanced and Free-Machining Titanium Alloys by Micrometer-Size Particle Distribution
Authors: Siemers Carsten , Laukart Judith , Zahra Badya , Rösler Joachim , Spotz Zdenek , Saksl Karel
Published: June 2011

The chip formation process of four different titanium alloys has been studied in several cutting experiments. Alloys containing more than 50% of a-phase at room temperature and aged metastable b-alloys form segmented chips independent of the cutting conditions. Solution treated metastable b-alloys show a cutting parameter dependent change from continuous to segmented chip formation. Lanthanum has been added to all four alloys. The microstructure of these alloys consists of a titanium matrix and micrometer-size particles. The presence of grain boundary particles leads to enhanced grain stability at elevated temperatures. In addition, short chips are observed during metal cutting only in case pure metallic rare-earth metal particles are present.
Compression Creep at 240°C of Extruded Magnesium Alloys Containing Gadolinium
Authors: Dieringa Hajo , Hort Norbert , Mueller Soeren , Kainer Karl Ulrich
Published: June 2011

For uses at high temperatures, magnesium alloys containing rare earths have proven to be very suitable. High proportions of melting precipitates contribute to strengthening, even at temperatures above 200°C. If these alloys are extruded, their creep resistance rises even further due to the resulting fine-grained structure. In this paper, magnesium alloys with 10% Gd and additional small amounts of La and Nd are compared with WE43 for compression creep at temperatures of 240°C and stresses between 80 and 150 MPa. The minimum creep rates are determined and the stress exponent evaluated in accordance with the Norton equation. By calculating the threshold stress, the true stress exponents are determined.
The Effect of Ni on the High-Temperature Strength of Al-Si Cast Alloys
Authors: Stadler Florian , Antrekowitsch Helmut , Fragner Werner , Kaufmann Helmut , Uggowitzer Peter J.
Published: June 2011

In order to investigate the effect of Ni on the high-temperature strength of Al-Si cast alloys, tensile properties of hypoeutectic and eutectic alloys were determined at 250 °C after long-term annealing at test temperature. LOM- and SEM-analysis revealed the existence of Al3Ni-phases in close contact to eutectic Si. It was shown that the strength can be increased by the addition of Ni, though just to a certain level, depending on the fraction of eutectic phase in the alloy. The alloys were considered as a coarse two-phase system where a hardening effect is caused by load transfer to the harder phase, which requires a certain connectivity/contiguity of the latter. The paper describes the extent of contiguity of the eutectic as well as the hard silicon and Al3Ni-phases within the eutectic, and discusses their contribution to an enhanced strength of Al-Si alloys at elevated temperatures.
Modeling Bolt Load Retention of Ca Modified AS41 Using Compliance-Creep Method
Authors: Anopuo Okechukwu , Huang Yuan Ding , Hort Norbert , Kainer Karl Ulrich , Maier Petra
Published: June 2011

Adequate quantification of the degree of fastener clamp load retained at bolted joint of Mg-Al alloys is crucial to develop new elevated temperature resistant Mg-alloys. Several attempts have been made in the past to model Bolt Load Retention (BLR) behaviour of Mg-alloys using different approaches. It must be mentioned that whereas these models attempt to predict BLR of the alloys investigated, the results of the models differ in most cases with the experiments by great margin. The BLR behaviour of Mg-alloy is geometry and material dependent. This means that, the configuration of the test sample, the compliance of the bolt/joint and creep response of the material under investigation play important role in determining the joint response under load and temperature. In this work, BLR and creep behaviour of Ca modified AS41 is investigated and compared to that of Mg4Al and AS41. A compliance-creep approach is used to model the response of these Mg-Al alloys at bolted joints. The model prediction of the BLR response and experimental results as obtained in this work are in good agreement. AS41+0.15 % Ca shows improved creep and BLR properties up to 175 °C. A correlation between the microstructures, creep and BLR results reveal that the formation of a ternary CaMgSi phase is responsible for the improved elevated temperature behaviour.
The Aging Response of a Metastable β Ti Alloy, BTi-6554
Authors: Wang Yong Qiang , Wang Gui , Wang Wei Qi , Kent Damon , Dargusch Matthew S.
Published: June 2011

In this study the effects of different aging heat treatments on the properties and microstructure of a high strength, high toughness metastable β Ti, BTi-6554 (Ti-6Cr-5Mo-5V-4Al), have been compared. An initial β phase solution treatment was followed by aging at moderate temperatures in the α/β dual phase zone by either step aging directly from the solution treatment temperature or by quenching to room temperature prior to the aging heat treatment. The differing heat treatment methods have significant effects on the microstructure and mechanical properties.
Solidification Microstructure and Mechanical Properties of Hot Rolled and Annealed Mg Sheet Produced through Twin Roll Casting Route
Authors: Aljarrah M. , Essadiqi Elhachmi , Kang D.H. , Jung In Ho
Published: June 2011

The use of wrought magnesium for automobile structural components is an important component of the mass reduction strategy for automobiles to improve their fuel efficiency. Compared to Direct chill casting, Twin Roll Casting (TRC) allows major reduction of hot rolling steps in the production of Mg sheet due to the thin thickness of the as-cast strip. This TRC route can substantially reduce the time and cost to produce Mg alloy sheet product. In this work, AZ31 magnesium alloy was casted to 5 and 6 mm thick strips under different process conditions. Microstructure of these strips was analyzed using optical microscopy, SEM and EPMA. TRC strip was annealed under two different conditions: 2 hours at 330 and 1 hour at 400°C. It has been found that heat treatment at 400°C for 1 hour reduces centerline segregation significantly. TRC strips were rolled down to 2 mm and annealed at 450°C for 2 minutes. The average grain size was 4-6 µm and mechanical properties were comparable with commercial AZ31 sheet.
Effect of Hot Rolling on Microstructure and Texture Evolution of Mg-Li Based Alloy
Authors: Kumar Vinod , Govind  , Shekhar Rajiv , Balani Kantesh
Published: June 2011

Mg-Li based alloy, namely Mg-9%Li-5%Al-3%Sn-1%Zn (LATZ9531) was cast and consequently hot rolled at ~573K. In the present study, as cast and hot rolled structural features has been investigated by scanning electron microscope and electron back scattered diffraction (EBSD). Phase analysis revealed presence of major Mg-rich α-phase and Li-rich β-phase. Significant crystallographic texture evolution due to conventional hot rolling process was observed due to the increased activity of the non-basal slip mode.
Effect of Al-Ti-B Based Master Alloys on Grain Refinement and Hot Tearing Susceptibility of AZ91E Magnesium Alloy
Authors: Abdallah Elsayed , Ravindran Comondore , Murty B.S
Published: June 2011

The objective of this study was to examine the potential of Al-5Ti-1B and Al-1Ti-3B master alloys in reducing the hot tearing susceptibility of AZ91E magnesium alloy. The low penetration of magnesium alloys for structural automotive applications can be attributed to their poor castability during permanent mould casting. An improvement in the castability of magnesium alloys will result in the production of larger castings for automotive applications and a reduction in vehicle weight. The addition levels examined for both master alloys were 0.1, 0.2, 0.5 and 1.0 wt.%. The master alloys were added to the AZ91E alloy and stirred for 30 seconds. For the graphite mould castings used to observe grain refinement, the pouring and mould temperatures were 720 and 750 °C respectively. The hot tear castings were produced using a “dog bone” shaped H-13 tool steel mould. The pouring and mould temperatures were 720 and 180 °C respectively. Without master alloy addition, the base AZ91E casting had severe hot tears. The addition of Al-5Ti-1B slightly reduced hot tears while Al-1Ti-3B addition significantly reduced hot tears. The addition of Al-1Ti-3B also significantly reduced the grain size of the castings from 113 µm in the base alloy to 72 µm with 1.0 wt.% addition. The addition of Al-5Ti-1B did not lead to a reduction of hot tears because of large TiAl3 particles acting as stress risers during solidification.
Stress Corrosion Cracking of a New Rare- Earth Containing Magnesium Alloy, Elektron21 Compared with AZ91E
Authors: Padekar Bharat S. , Raja V.S. , Singh Raman R.K. , Paul Lyon
Published: June 2011

Stress corrosion cracking (SCC) of a rare-earth (RE) containing and Al-free magnesium alloy, Elektron21 was studied using constant load test (CLT) in 0.1N NaCl solution saturated with Mg(OH)2.For comparison a common Al-containing and RE-free alloy, AZ91E was investigated. In CLT the threshold stress for SCC (σscc) for AZ91E was found to be 60% of the yield stress, whereas Elektron21 showed immunity to SCC even at stresses in the proximity of yield stress. The susceptibility of AZ91E to SCC and immunity of Elektron21 during CLT have been confirmed by fractography.
Electrochemical Corrosion Behaviour of ZE41 and QE22 Magnesium Alloys
Authors: Kannan M. Bobby , Blawert Carsten , Dietzel Wolfgang
Published: June 2011

The study suggests that the rare-earths containing magnesium alloys ZE41 and QE22 exhibit a poorer corrosion resistance than the AZ80 magnesium alloy. Electrochemical experiments showed that the two rare-earths containing alloys are highly susceptible to localized corrosion. Post corrosion analysis revealed intergranular and pitting corrosion in ZE41, whereas QE22 alloy underwent only pitting corrosion.
Intermetallic Particles-Induced Pitting Corrosion in 6061-T651 Aluminium Alloy
Authors: Mutombo Kalenda
Published: June 2011

The polished 6061-T651 aluminium alloy was immersed in 3.5% NaCl solution with about 7 ppm dissolved oxygen. Scanning Electron Microscopy equipped with Energy dispersive X-ray Spectroscopy revealed the presence of Al-Si-Fe-containing particles that acted as cathodic sites and promoted the matrix dissolution. The effect of pH and chloride solution is assessed.
Surface Wear Improvement of Al-Alloys by Amorphous Iron-Based Flame-Sprayed Coatings
Authors: Voyer Joel
Published: June 2011

Partially amorphous iron-based coatings were produced onto aluminium using a powder flame-spraying process with a commercially available feedstock powder (Nanosteel SHS-7170) obtained from the Nanosteel Company Inc.. Several coating properties such as the microstructure, porosity, phase content, micro-hardness, and wear resistance were evaluated in the as-sprayed condition. As shown by the results obtained, the powder flame iron-based coatings perform relatively well in term of wear resistance in comparison with similar coatings produced using other expensive thermal spray techniques. Furthermore, this study shows that all the coating properties (microstructure, porosity, phase content, hardness and wear performance) depend strongly on the flame spraying parameters used. Finally, this paper demonstrates clearly that the flame-spray process may be used to produce amorphous iron-based coatings having a good wear resistance, and that this process appears to be a suitable inexpensive alternative to plasma or HVOF processes based on the present results.
Characterization of Ni-P/TiO2 MMC Coatings Prepared by Electroless Plating Process on Mg-Nd-Zn-Zr Magnesium Alloys
Authors: Guo Xing Wu , Wang Shao Hua , Yang Hai Yan , Peng Li Ming , Ding Wen Jiang
Published: June 2011

Ni-P/TiO2 metal matrix composite (MMC) coatings were prepared by electroless plating process combined with sol-gel technology on Mg-3.0Nd-2.0Zn-0.4Zr (wt.%, NZ30K) magnesium alloys. The reinforcement of TiO2 nanoparticles was added into the solution of electroless plating in the form of transparent alcoholic sol. The microstructures and compositions of the prepared Ni-P/TiO2 MMC coatings were investigated by Field Emission Scanning Electron Microscopy (FE-SEM). The phase composition of the coating was analyzed by X-ray diffraction (XRD) facilities. It was found that the TiO2 nanoparticles were highly dispersed in the coating matrix. The microhardness of Ni-P/TiO2 MMC coating was far higher than those of NZ30K substrate and Ni-P coating due to the incorporation of in-situ formed TiO2 nanoparticles. Electrochemical measurements indicated that the corrosion resistance of Ni-P/TiO2 MMC coatings was superior to NZ30K substrate but no obvious significant change could be seen compared to Ni-P coating.
Study on the Characteristic and Effect of the Nickel Ferrite Spinel Cermet as Al Electrolysis Inert Anode
Authors: Liu Yi Han , Sun Hua Wei , Wei Wei
Published: June 2011

Inert anode or non-consume anode possesses more advantages than traditional carbon anode in Al electrolysis. Because it does not consume during electrolysis, the inert anode can maintain its dimension; and this will led to the Al electrolysis easy to operate and administrate. Especially, the inert anode does not emit the carbon dioxide during the Al production, owing to its not consuming, and this has made the inert anode become one of the highlights in Al electrolysis industry. Unfortunately, up till now, there is no any material can endure the erosion of cryolite molten salt, keep its good electrolytic conductivity and be agreeable in price. In this paper, a cermet material composed of 85% nickel ferrite spinel and 15% metallic Ag has been studied, aim at exploring a kind of material which can be used as Al electrolysis inert anode. The works mainly focus on improving the boundary and microstructure between the metallic Ag and the nickel ferrite spinel interface. The practice test of this cermet material being used as Al electrolysis anode has been done in small laboratory scale, and its effect is quite better. We can draw the conclusion that the characteristic such as the conductivity, corrosion resistance and hot shock property of the cermet material can be greatly improved to meet the requirement of Al electrolysis by means of optimizing the spinel/metal interface, and once we settle the technique of fabricating this kind of anode to enough dimension, can we use this kind of material as inert anode in Al electrolysis industry to reduce the gas emission of carbon dioxide.
Perspectives for the Application of Variable Thickness Aluminium Tubes in Hydroforming of Complex Tubes
Authors: Bihamta Reza , Bui Quang Hien , Guillot Michel , D'Amours Guillaume , Rahem Ahmed , Fafard Mario
Published: June 2011

Tubular products have very important applications in various areas especially in the transportation industries. For instance, in the structure of cars there are various tubular products like roof headers, engine cradles, roof rails and frame rails with complex geometries which most of them need multiple steps like tube drawing, tube bending and hydroforming for their production. Based on the recent studies by this group, it was proven that in most of the structural tubular parts in the cars it was not necessary to have constant thickness along the axial direction of tube and it will be considered as overdesign and the overall weight of structures can be reduced considerably by using variable thickness tubes. In this paper, the variable thickness tube drawing and its applications in the tube bending and hydroforming applications were studied. The results showed that this process can have important role in reduction of defective parts in the production of complex tubes by the tube hydroforming method. However especial considerations should be taken into account in the design of thickness distribution along axial direction of these kinds of tubes to avoid problems in the drawing step and as well in the bending and hydroforming steps.
Advanced 5xxx-, 6xxx- and 7xxx- Aluminium Alloys for Applications in Automotive and Consumer Electronics
Authors: Schulz Peter , Berneder Josef , Uffelmann Dirk , Zelger Christian , Melzer Carsten
Published: June 2011

Aluminium alloys offer an excellent balance of strength, light weight, good formability and corrosion resistance, together with capability for decorative & functional surface treatments. They have become widely used for automotive and consumer electronic applications. AMAG rolling has developed advanced 5xxx-, 6xxx- and 7xxx- alloys and processes to extend use in these industries. Examples are shown and metallurgical aspects explained.
Effect of Iron Addition to Aluminium on the Structure and Properties of Wires Used for Electrical Purposes
Authors: Jabłoński Michał , Knych Tadeusz , Smyrak Beata
Published: June 2011

Eight hypoeutectic aluminium alloys with iron content within the range of 0.07-1.09% by weight, were examined. The structure, the mechanical and electrical properties of wires used for electrical purposes were studied. The batch material for the drawing process was wire rod obtained from the continuous casting and rolling line by Continuus-Properzi method. It has shown a linear relationship between mechanical properties of wire rod, a higher plasticity of wire after drawing process and an increase in thermal resistance of the material with increasing iron content. The findings enable to draw conclusions of basic and application characteristics, pointing to the possibility of using aluminium with higher iron content in the wire drawing process of small diameter and microwires for the production of automotive bundles, accumulator cables and winding wires.
Chemically Milled Alpha-Case Layer from Ti-6Al-4V Alloy Investment Cast
Authors: Mutombo Kalenda , Russouw P. , Govender G.
Published: June 2011

The as cast Ti6Al4V, obtained after investment casting with yttria stabilized zirconia face-coat, was chemically milled using a mixture of hydrofluoric acid and nitric acid. This process removed completely the alpha-case layer. Lower hardness and almost no oxygen contamination are revealed after microhardness measurement, Energy dispersive X-ray and X-ray diffraction analysis. The hydrofluoric acid/nitric acid ratio, pickled Ti6Al4V surface, pickling efficiency, pickling rate, immersion time and solution temperature are discussed.
Anisotropy of Flow during Forging of Rolled AZ31B Plate in Transverse Direction
Authors: Rao K.P. , Prasad Y.V.R.K. , Suresh K.
Published: June 2011

Forging of a rib-web shape in rolled AZ31B magnesium alloy was conducted in the transverse direction at speeds of 0.01-10 mm s-1in the temperature range 300-500 °C with the objective of validating the flow anisotropy. The finite element programme DEFORM was used to simulate the forging process to obtain the local values of strain and strain rate. Forgings done along the transverse direction at temperatures higher than 400 °C resulted in a symmetrical cup-shape while those done at lower temperatures exhibited an elliptical boat-shape with the major axis coinciding with the rolling direction and the minor axis aligning with the normal direction. This anisotropy of flow was due to the strong basal texture in the rolled plate and the dominance of prismatic slip at lower temperatures. At higher temperatures, pyramidal slip dominates along with cross- slip as the recovery mechanism, which reinstates the symmetry of flow by destroying the initial texture.
Magnesium Permanent Mold Castings Optimization
Authors: Elsayed Fady Refaat , Hort Norbert , Salgado Ordorica Mario Alberto , Kainer Karl Ulrich
Published: June 2011

Permanent mold casting is a well-established route for casting large magnesium alloys components. Casting parameters like superheat, mold temperature, and holding time can often result in inhomogeneous properties, porosity, and segregation problems in the cast part. In order to optimize the casting process, control of the casting parameters including mold temperatures and holding times is essential to promote directional solidification, and ensure defect free homogenous structure. Binary Mg-9wt.%Al and Mg-10wt.%Gd alloys were used to investigate the effect of casting parameters such as melt temperature and holding time on the part macro and microstructure.
Mechanical Properties of Mill-Annealed Ti6Al4V Investment Cast
Authors: Mutombo Kalenda , Rossouw P. , Govender G.
Published: June 2011

Ti6Al4V alloy, produced by investment casting using yttria stabilized zirconia, was machined and then mill-annealed in vacuum furnace. The ultimate strength, yield strength and percentage elongation were largely improved compared to the same alloy in the as cast condition. The mill annealing temperature and time strongly affected the ultimate strength, 0.2% yield strength and the percentage elongation.
Influence of Si and Mg Contents on the Mechanical Behavior of Al-Mg-Si Alloys in the Semi-Solid State under Isothermal and Non-Isothermal Conditions
Authors: Giraud Eliane , Suéry Michel , Coret Michel
Published: June 2011

The shear behavior of aluminum alloys containing increased amounts of Si or Mg compared with the 6061 alloy has been investigated by carrying out isothermal and non-isothermal tests in the mushy state during solidification. In isothermal conditions, it is shown that (i) an increase in Mg content leads to a more resistant semi-solid alloy compared with the 6061 alloy for the same solid fraction and (ii) an increase in Si content leads to a more brittle mushy alloy. In non-isothermal conditions, stress increases continuously with decreasing temperature with the formation of cracks for some compositions. This study shows that an increase in Mg content seems to be the most appropriate solution to reduce the formation of cracks in a solidifying 6061 alloy.
The Continuous Casting Technology of the Aluminum Rod Assigned for the Wire for Electrical Purposes
Authors: Knych Tadeusz , Uliasz Piotr , Piwowarska Marzena
Published: June 2011

New technologies of the production of the aluminium charge assigned for drawing, including the tests on the process of continuous casting (CC). This type of technology, which includes the casting of copper and zinc, is widely spread in the world (trademarks: Upcast, Rautomead and Vertic). Yet, there is a lack of experience in the production and reproduction of the cast wires made of aluminium and its alloys assigned for electrical purposes. That is why the authors of the work aimed at investigating the casting process of the aluminium wires obtained with the technology of continuous casting.
Studies and Researches Concerning Utilization of some Al-Ni Alloys with High Concentration of Ni Content as Catalytic Agents in Hydrogenation Reactions of the Organic Compound
Authors: Alexandru Cernaianu Stoianovic Antoniu
Published: June 2011

This paper presents the method of obtaining in conditions of ultra speed solidification of Al-Ni alloys with high Ni content on purpose to search the catalytic action of the NiAl3as a separate compound. It is characterized to catalyze from Ni-Al alloy ultra rapid solidificated in fibers with lengths between 20-40 μm.
Effect of Nickel Addition on Microstructure and Mechanical Properties of Aluminum-Based Alloys
Authors: Hernández-Méndez F. , Altamirano-Torres A. , Miranda-Hernández José G. , Térres-Rojas Eduardo , Rocha-Rangel Enrique
Published: June 2011

In this work a comparative study between microstructure and mechanical properties of aluminum-nickel alloys with different contents of nickel was carried out. Alloys were produced by powders metallurgy. Characterization results indicates that the microstructure of the aluminum-nickel alloys present a thin and homogeneous distribution of an intermetallic compound in the aluminum’s matrix, identified as Al3Ni. Furthermore, it was find out that the amount of intermetallic Al3Ni increase as the nickel content in the alloy rises. Regarding the mechanical properties evaluated; it was establishes that the hardness, compression and flexion resistances also were improved due to the presence of the intermetallic compound.
Structural and Optical Characterization of CdSe Films Grown by Chemical Bath Deposition
Authors: Aguilar-Hernández J.R. , Espinosa-Bustamante A. , Hernández-Pérez M.A. , Contreras-Puente G.S. , Cárdenas-García M. , Zelaya-Angel O.
Published: June 2011

We present in this work experimental results and their analysis concerning the structural and optical characterization of cadmium selenide (CdSe) films grown by the Chemical Bath Deposition (CBD) technique, at different bath temperaturesTd: 0≤Td≤80 °C. Structural characterization was carried out by using X-ray diffraction, whereas optical characterization was done by using optical absorption and photoluminescence spectroscopies. X-ray results showed a change of the crystalline structure as a function ofTd, from the zincblende to wurzite one whenTdincreases from 0 to 80 °C. The respective band-gap,Eg,was calculated from the absorption spectrum giving rise to values in the range 1.85 to 2.30 eV, as a function also ofTd. Thses values are higher than the well accepted value of 1.75 eV for the CdSe bulk material. The radiative emission was analyzed throughout the photoluminescence (PL) spectra. All samples showed radiative emission above the band-gap, at room temperature, this radiative emission having a dependence on the pressure inside the cryostat. A quenching of the PL signal is observed when the pressure is decreased at values as low as 60 mTorr.
Synthesis and Mechanical Properties Evaluatioin of Waterborne PSA’S with Core-Shell Morphology
Authors: Mascorro R. , Corea M.
Published: June 2011

In this work, a series of Pressure Sensitive Adhesives (PSAs) of poly(n-butyl acrylate-2-ethyl hexyl acrylate- acrylic acid) were synthesized via emulsion polymerization. The PSAs particles were carried out in a semicontinuous process. Synthesis was carried out in two stages of thereaction. In the first, a core of poly(butyl acrylate-co-2-ethyl hexyl acrylate) with a composition of 50/50 wt%/wt % was synthesized, while in the second stage, the core was charged in the reactor as a seed; and was recovered with a poly(butyl acrylate-co-2-ethyl hexyl acrylate-co-acrylic acid) shell. The acrylic acid in the shell was varied between 0, 1, 3 and 5 wt%. The PSAs obtained were characterized by dynamic light scattering and zeta potential. The results of dynamic light scattering showed monodispersed particles with an average particle size of 350 nm, while the zeta potential results decreased as the acrylic acid content increased. The mechanical tests showed that the increase in acrylic acid content in the particle shell improves the adhesion properties. For peel adhesion, the maximum value was reached at 3 wt% of acrylic acid.
Influence of the Fluence and Substrate Temperature on the Structural and Optical Properties of CdSe Thin Films Prepared by Pulsed Laser Deposition
Authors: Hernández-Pérez M.A. , Aguilar-Hernández J.R. , Vargas-García Jorge Roberto , Contreras-Puente G.S. , Rangel-Salinas E. , Hernandez-Santiago Felipe , Vargas-Ramírez Marissa
Published: June 2011

Cadmium Selenide (CdSe) thin films were prepared by pulsed laser deposition using a Nd:YAG laser (355 nm). Films were grown by ablating a sintered pure CdSe target with fluences from 0.1 to 1.5 J/cm2 on corning glass, silicon (100) and quartz substrates. Deposition chamber was maintained under vacuum pressure while substrate temperature was increased from room temperature to 500°C in order to control the crystalline phase. All the films show mirror-like surface morphology. Atomic force microscopy (AFM) images shown that films have very flat surfaces with RMS values around 0.7 and 5 nm for room temperature and 500°C respectively. The X-ray diffraction analysis proves the presence of the cubic zinc blend phase for the CdSe films deposited at low temperature, at 400°C and at higher substrate temperature the hexagonal phase is present. TEM analysis shows that at 100°C the films are constituted by particles with an average size of 30nm in diameter. The optical properties of the films were determined from the UV-transmission spectra. The estimated band gap values of the films deposited at room temperature and at 400°C (0.1 J/cm2) were 1.87 and 1.70 eV respectively.
Effects of the Thermal Annealing with CdCl2 on the Optical Properties of CdS Thin Films Grown by Radio-Frequency Planar Magnetron Sputtering
Authors: Espinosa-Rosas M.R. , Aguilar-Hernández J.R. , Hernández-Contreras H. , Hernández-Pérez M.A. , Contreras-Puente G.S. , Cárdenas-García M. , Ortega-Nájera B.
Published: June 2011

We present in this work some results concerning the effects of the thermal annealing withCdCl2on the optical properties ofCdSthin films grown by radio-frequency planar magnetron sputtering technique, under optimized growth parameters: gas pressure, atmosphere, substrate temperature, power of plasma, etc. An improvement of the optical properties has been observed, mainly the presence of radiative emission (luminescence) at room temperature. This fact allowed us to carry out a deep study of the photoluminescence (PL) properties of theCdSfilms, in the range of temperature 10≤ T ≤ 300 K. Radiative emission at the high energy side has been observed and related to exitonic processes. Temperature quenching experiments gave rise to the calculation of the activation energies for each one of the radiative emissions (PLbands).
Characterization of Glass Forming Alloy Fe43.2Co28.8B19.2Si4.8Nb4 Processed by Spray Forming and Wedge Mold Casting Techniques
Authors: Rios C. Triveño , Afonso Conrado R. M. , Bolfarini Claudemiro , Botta Filho Walter José , Kiminami Claudio Shyinti
Published: June 2011

Bulk glassy alloys based on the Fe-Co-B-Si-Nb system have already achieved high levels of mechanical strength. The present work investigated the microstructural evolution of Fe43.2Co28.8B19.2Si4.8Nb4 alloy during the spray forming and wedge mold casting processes, with emphasis on the formation of amorphous phase. The microstructure was evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The region outer the spray deposit showed the formation of an amorphous structure with a thickness of ~2.5 mm, while that of the wedge-shaped sample exhibited a thickness of up to ~1.5 mm, suggesting that both processes show a promising potential for the production of bulk glass alloys.
Synthesis of Al2O3/Ti/TiN Functional Graded Materials by Means of Nitriding in Salts of Al2O3/Ti Composites
Authors: Miranda-Hernández José G. , Refugio-García Elizabeth , Garfias-García Elizabeth , Rocha-Rangel Enrique
Published: June 2011

The synthesis of Al2O3/Ti/TiN functional graded material (FGM) through the nitriding in salts of previously Al2O3-10 vol. % Ti fabricated composites was studied. The matrix for the preparation of the FGM is formulated of an Al2O3-based composite that presents a homogeneous dispersion of very fine metallic titanium particles. After nitriding process, microstructural observations were carry out on the transversal zone of the materials’ surface showing the presence of a very thin film of about 37 µm of a constituent that was identified as TiN. Micro-hardness measurements performed from the surface to the core of the FGM confirm an increment on the hardness near the material’s surface.
Stem Cells for Cardiac Repair: Status, Mechanisms, and New Strategies
Authors: Mingliang Ren , Bo Zhang , Zhengguo Wang
Published: June 2011

Faced with the end stage of heart disease, the current treatments only slow worsening of heart failure. Stem cells have the potential of self-renewal and differentiation. It is expected to replace and repair damaged myocardium. But many clinical trials have shown that the stem cell therapy of heart failure is modest or not effective. The possible causes for the limited effects of stem cell in curing heart failure are the stem cells which have been transplanted into the ischemic heart muscle may suffer low survival rate, affected by inflammatory molecules, proapoptotic factor, and lack of nutrients and oxygen, and then the stem cells which home and have been completely transplanted to the site of myocardial infarction become very small. Therefore, through preconditioning of stem cells and appropriate choice of genes for mesenchymal stem cell modification to improve the survival rate of stem cells, ability in homing and promoting angiogenesis may become the newly effective strategies for the application of stem cells therapy in heart failure.
Arginase Inhibitor in the Pharmacological Correction of Endothelial Dysfunction
Authors: Pokrovskiy Mihail V. , Korokin Mihail V. , Tsepeleva Svetlana A. , Pokrovskaya Tatyana G. , Gureev Vladimir V. , Konovalova Elena A. , Gudyrev Oleg S. , Kochkarov Vladimir I. , Korokina Liliya V. , Dudina Eleonora N. , Babko Anna V. , Terehova Elena G.
Published: June 2011

This paper is about a way of correction of endothelial dysfunction with the inhibitor of arginase: L-norvaline. There is an imbalance between vasoconstriction and vasodilatation factors of endothelium on the basis of endothelial dysfunction. Among vasodilatation agents, nitrogen oxide plays the basic role. Amino acid L-arginine serves as a source of molecules of nitrogen oxide in an organism. Because of the high activity of arginase enzyme which catalyzes the hydrolysis of L-arginine into ornithine and urea, the bioavailability of nitrogen oxide decreases. The inhibitors of arginase suppress the activity of the given enzyme, raising and production of nitrogen oxide, preventing the development of endothelial dysfunction.
Determination of Glucosamine in Human Plasma by High-Performance Liquid Chromatography-Atmospheric Pressure Chemical Ionization Source-Tandem Mass Spectrometry
Authors: Zhou Xingchen , Cheng Zeneng , Ran Liling , Guo Xin , Liu Zhi , Yu Peng
Published: June 2011

A sensitive, specific, and rapid high-performance liquid chromatography-atmospheric pressure chemical ionization source-tandem mass spectrometry (HPLC-APCI-MS/MS) method for the determination of glucosamine in human plasma was developed and validated. Plasma samples were processed by protein precipitation with dehydrated ethanol, and the chromatographic separation was performed on an Agilent XDB-C18 column with a mobile phase of methanol—0.2% formic acid solution (70 : 30, v/v). Mass spectrometric quantification was carried out in the multiple reaction monitoring (MRM) mode, monitoring ion transitions of m/z 180.1 to m/z 162.1 with collision energy (CE) of 2 eV for glucosamine and m/z 181.1 to m/z 163.1 with CE of 2 eV for the internal standard (IS) in positive ion mode. The linear calibration curves covered a concentration range of 53.27–3409 ng/mL with a lower limit of quantification (LLOQ) of 53.27 ng/mL. The extraction recovery of glucosamine was greater than 101.7%. The intra- and interday precisions for glucosamine were less than 10%, and the accuracies were between 93.7% and 102.6%, determined from quality control (QC) samples of three representative concentrations. The method has been successfully applied to determining the plasma concentration of glucosamine in a clinical pharmacokinetic study involving 20 healthy Chinese male volunteers.
Association between the c. 2495 A>G ATP7B Polymorphism and Sporadic Alzheimer′s Disease
Authors: Bucossi Serena , Mariani Stefania , Ventriglia Mariacarla , Polimanti Renato , Gennarelli Massimo , Bonvicini Cristian , Pasqualetti Patrizio , Scrascia Federica , Migliore Simone , Vernieri Fabrizio , Rossini Paolo M. , Squitti Rosanna
Published: June 2011

Nonceruloplasmin‐bound copper (“free”) is reported to be elevated in Alzheimer′s disease (AD). In Wilson′s disease (WD) Cu‐ATPase 7B protein tightly controls free copper body levels. To explore whether the ATP7B gene harbours susceptibility loci for AD, we screened 180 AD chromosomes for sequence changes in exons 2, 5, 8, 10, 14, and 16, where most of the Mediterranean WD‐causing mutations lie. No WD mutation, but sequence changes corresponding to c.1216 T>G Single‐Nucleotide Polymorphism (SNP) and c.2495 A>G SNP were found. Thereafter, we genotyped 190 AD patients and 164 controls for these SNPs frequencies estimation. Logistic regression analyses revealed either a trend for the c.1216 SNP (P = .074) or a higher frequency for c.2495 SNP of the GG genotype in patients, increasing the probability of AD by 74% (P = .028). Presence of the GG genotype in ATP7B c.2495 could account for copper dysfunction in AD which has been shown to raise the probability of the disease.
End moraines and deglaciation chronology in northern Canada with special reference to southern Baffin Island
Authors: Blake W
Published: June 2011

An extensive system of end moraines near Frobisher Bay and on Foxe Peninsula, in southern Baffin Island, are described for the first time. The section crossing Frobisher Bay can be traced for some 325 miles (525 km). The high level "strandlines" described from
the southwest side of Frobisher Bay by several workers are in reality a combination of kame terraces, lateral moraines, and marginal lake terraces - all related to the moraine system and formed beside a major ice lobe entering Frobisher Bay from the northwest. Numerous radiocarbon dates show that:
1) ice from Hudson Strait impinged on the south coast of Baffin Island during the last glaciation, carry­ing marine shells far above the level of marine submergence; 2) all or nearly all of Hudson Strait was filled by ice 9, 000 year s ago, but was ice free by 8,000 years ago, and the sea had
reached the limit of submergence south of James Bay a short time after 8,000 years B.P.; 3) the major moraines crossing Frobisher Bay, near Rae Isthmus at the south end of Melville Peninsula, and at MacAlpine Lake, District of Mackenzie, were forming some 8,200 years ago, but parts of the moraine
system in northern Baffin Island probably formed earlier; 4) moraine formation contin1ed for several hundred years after 8,200 B. P.; 5) innermost Frobisher Bay and Foxe Basin were ice free by 6,900 to 6,700 years ago; and 6) Amadjuak Lake was free of ice before 4,500 B. P., although the last mass
of ice, which lay northeast of this lake, may have still been in existence then. The orientation of the moraines in southern Baffin Island and radiocarbon dates from widely spaced areas in northern Canada show the need for reappraisal of the "Cockburn Glacial Phase" hypothesis and the postulated
position of the ice-edge 9,500 or 9,000 to 8,000 years ago (cf. Falconer et al. , 1965a, 1965b).
Detailed outcrop and core measured sections of Upper Cambrian and Middle Ordovician sandstones (and associated facies), southwestern Ontario
Authors: Hamblin A P
Published: June 2011

Upper Cambrian and Middle Ordovician units, particularly the Potsdam and Shadow Lake sandstone units, of southwestern Ontario may harbour potential for natural gas resources, groundwater resources, Carbon Capture and Storage (CCS), and/or toxic waste disposal,
but have not been fully studied in detail over the region. This report presents 5 outcrop and 16 core measured sections of these strata,
descriptions of the facies encountered, and a few comments on their resource potential. Potsdam (Mount Simon) Formation facies include dominant thick bedded medium to coarse sandstone, arkosic coarse sandstone to conglomerate, and minor dark siltstone and dolostone, interpreted to represent
deposition in a shallow nearshore to shoreline setting during initial upper Cambrian transgression.
Theresa (Eau Claire) Formation facies include interbedded sandy dolostone and dolomitic fine to medium grained sandstone and minor bioturbated siltstone, interpreted to represent shallow subtidal to nearshore deposition. Shadow Lake Formation facies include dominant well sorted medium grained
sandstone, poorly sorted fine to coarse sandstone, reddish mottled mudstone, and grey siltstone interbedded with greenish calcisiltite/limestone/dolostone in the upper parts of the formation. This suite is interpreted to represent deposition in shallow nearshore, shoreline and subaerial environments
during the initial Middle Ordovician regional transgression over the peneplained Precambrian and Upper Cambrian unconformity surface, from which the detritus was derived. The porous and permeable Potsdam Formation yields oil and gas, and may provide further unstudied potential for hydrocarbons,
groundwater, CCS or toxic waste disposal. The Shadow Lake Formation is not currently recognized to produce hydrocarbons (although these strata are in reservoir continuity with productive Cambrian units in places), but harbours significant unevaluated potential for oil and gas, groundwater and
perhaps CCS.