XPS study of the corrosion resisting composite alloying layer obtained by double glow plasma with the brush plating Ni interlayer

The Ni-Cr-Mo-Cu multi-element surface alloying with the electric brushplating Ni interlayer on the low carbon steel substrate has been investigated. By theelectrochemical method in 3.5 percent (mass fraction) NaCl solution, the corrosion resistance of thecomposite alloying layer and single alloying layer is determined. The experimental results showthat the corrosion resistance of the composite alloying layer is obviously better than that of thesingle alloying layer. The structure and composition of passive films formed on the two kinds ofalloyed layers after electrochemical tests in 3.5 percent NaCl solution have been studied usingX-ray photoelectron spectroscopy (XPS). It is concluded that the double glow plasma surface alloyingof low carbon steel with the electric brush plating Ni interlayer is an appropriate technique toenhance the corrosion resistance compared with the single double glow surface alloying.

Structure and electrochemical characteristics of LaNi_5-Ti_(0.10)Zr_(0.16)V_(0.34)Cr_(0.10)Ni_(0.30) composite alloy electrode

Composite LaNi5+x wt.% Ti0.10Zr0.16V0.34Cr0.10Ni0.30 (x=0, 1, 5, 10) alloys were prepared by two-step re-melting. X-ray diffractometer (XRD), scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS), inductively coupled plasma (ICP) and electrochemical impedance spectroscopy (EIS) analyses showed that the matrix phase of LaNi5 alloy with CaCu5 structure remained unchanged after additive alloy was added, the amount of the second phase increased with increasing x. The synergetic effect withi...

Electrodeposition of Ni-W Amorphous Alloy and Ni-W-SiC Composite Deposits

Ni-W alloys and their composite deposits are electroplated on the metals when an appropriate complex agent is selected on the base of the theories of electrochemistry and complex chemistry, and the principle of induced codeposition. Effects of the bath composition, pH value, temperature and current density on the electrode position of Ni-W alloys and their composite deposits have been investigated, and the effect of heat treatment temperature on the hardness, structure and cohesive force of the amorphous Ni-W alloys and their composite deposits are also discussed. Results showed that the alloys containing more than 44 wt pct W content and the composite deposits containing 7.8 wt pct SiC content could be obtained by making use of the appropriate bath composition and plating conditions. Alloys and their composite deposits with over 44 wt pct W content show amorphous structure. The hardness of amorphous Ni-W alloys and their composite deposits increases obviously when heated, and can reach to 1350 HV and 1520 HV respectively for 46 wt pct W content. The cohesion on Cu, carbon steel and stainless steel is very good.

Phase Structure and Cycle Stabilities of Mg_2Ni/Mm_(0.3)Ml_(0.7)Ni_(3.55)Co_(0.75)Mn_(0.4)Al_(0.3) Composite Hydrogen Storage Alloys Prepared by Two-step re-melting

Mm0.3Ml0.7Ni3.55Co0.75Mn0.4-Al0.3 alloy has high chemical activity and favorable plateaus pressure. Mg2Ni is in favor of high hydrogen storage capacity and low weight, but it is difficult to be activated. In order to improve the capacity and cycle performances of hydrogen-storage alloy electrodes, Mm0.3Ml0.7Ni3.55Co0.75Mn0.4-Al0.3-x%Mg2Ni(x=0, 5, 10, 30) composite hydrogen storage alloys prepared by two-step re-melting were investigated in this work. The influences of Mg2Ni content on the cycle stabilities were analyzed by electrochemical methods. It was observed by XRD that the main phase of all the alloys is LaNi5 and the crystal lattice parameters of LaNi5 are changed with the increasing of x value, i.e, a-axis and unit cell volume decrease and c-axis decreases nonlinearly. The c-axis of alloy with x=5 is larger than the others. With the increasing of x value, capacity retentions of the composite hydrogen storage alloys rise from 66.21% while x=0 to 82.04% while x=10, but the capacity retention of the composite alloy with 30% Mg2Ni declines because of its decreasing axial ratio. More over, the composite alloy with 5% Mg2Ni shows the best cycle stability and higher discharge capacity, and it is an appropriate candidate for battery materials.

U.S. Department of Energy Research in Intermetallic Alloys and Composites

The program of the Division of Materials Sciences for.intermetallic materials will be surveyed. This program is carried out at Department of Energy National Laboratories and at U.S. universities. Areas of research include theory and material simulation, microalloying, high resolution studies of structure and composition, mechanical properties, point defects and dislocation mechanics, phase transformations, and processing. Finally, general considerations will be discussed for the future program.

Microstructure and Corrosion Resistance of a Novel AlNiLa Lightweight Medium Entropy Amorphous Alloy Composites

A new type of lightweight AlNiLa medium entropy amorphous alloy composite ribbons(labled as MEAAC ribbons)were prepared by vacuum arc melting technology and high-speed single roller meltspinning method.The microstructure and thermal stability of MEAAC ribbons were examined using X-ray diffraction,differential scanning calorimeter,and scanning electron microscope.Meanwhile,the hardness and surface roughness of these ribbons were measured by Vickers microhardness tester and atomic force microscope.The potentiodynamic polarization curves and electrochemical impedance spectroscopy(EIS)were applied to investigate the corrosion behavior of these MEAAC ribbons in simulated seawater(3.5wt%NaCl corrosive solution)at room temperature.The results demonstrate that AlNiLa MEAAC ribbons in the as-received state are mainly composed of amorphous phase and intermetallic compounds.The hardness values of all melt-spun ribbons are above 310 HV_(0.1).With the increase of Al content,the linear polarization resistances of four various AlNiLa MEAAC ribbons are negligibly different numerically.It is also found that Al_(45)Ni_(27.5)La_(27.5) MEAAC ribbons have the most positive corrosion potential and the smallest corrosion current density at the same time;hence it may be a kind of potential material for metal surface protection in harsh ocean environment.

Microstructure and Eutectic Transformation of Squeeze Casting Alumina/Zinc Alloy Composites

Alumina fiber-reinforced zinc alloy composites were manufactured by squeeze casting, and the eutectic transformation in the zinc alloy composites was studied. The results indicate that there is a fine and close interface between the fiber and the matrix, and the alloy elements can improve the combination between the fibers and the matrix in the composites. The fibers can serve as the sites of heterogeneous nucleation of the eutectic in the zinc alloy during the solidification of the composites, and the silicon on the interface between the fibers and the matrix plays a leading role during the coupled growth of the eutectic so that the eutectic transformation of the composites consists of Al-Si eutectic transformation and Zn-AI eutectic transformation.

Microstructure and Hydrogen Absorption Pro-perties of Mg/MmNi_(5-x) (CoAlMn)_x Composite Prepared by Mechanical Alloying

The microstructure ofthe Mg/MmNi5-x (CoAlMn )x composite hydrogen storage material preparedby the method of mechanical alloyingwas characterized by X-ray diffraction, SEM and particle size distribution analysis. By measuring PCTcurves, the hydrogen absorption properties of the composite was evaluated.The results show that nanocrystallinecomposite structure can be obtainedunder adequate ball milling condition. The reactive activation and hydrogen absorption capacity are improved compared with the sole MmNi5-x(CoAlMn)x alloy. The effect ofmagnesium on the microstructure andhydrogen absorption properties of thecomposite were also evaluated.

Microstructural Characterization and Mechanical Properties of VB_2/A390 Composite Alloy

In this work, we make the best use of the vanadium element; a series of A1-V-B alloys and VB2/A390 composite alloys were fabricated. For Ak-10V-6B alloy, the grain size of VB2 can be controlled within about 1 μm and is distributed uniformly in the AI matrix. Further, it can be found that VB2 promises to be a useful reinforcement particle for piston alloy. The addition of VB2 can improve the mechanical properties of the A390 composite alloys significantly. The results show that with 1 % VB2 addition, A390 composite alloy exhibits the best performance. Compared with the A390 alloy, the coefficient of thermal expansion is 13.2 × 10^-6 K-1, which decreased by 12.6%; the average Brinell hardness can reach 156.5 HB, wear weight loss decreased by 28.9% and ultimate tensile strength at 25℃ （UTS25 ℃） can reach 355 MPa, which increased by 36.5%.

A Review on Utilization of Light Weight Fly Ash Cenosphere as Filler in both Polymer and Alloy-Based Composites

Fly Ash Cenospheres(FACs)are obtained from the coal power plants in the form of hollow spherical particles by burning the coal.FAC was started to use in early 1980-1985 as lightweight filler material in producing composites of cementitious and at present many researchers are focusing on use of FAC as filler in polymer and metals.In this paper,the systematic review on research activities and application of FAC in manufacturing light weight products are done.The influence of FAC on the physical and mechanical properties of incorporated polymer and alloy-based composites were summarized.Prospects of future for its use were also suggested and summarized in this paper.

Superplasticity in an Aluminum Alloy 6061/Al_2O_3p Composite

The superplasticity of an Al203p/6061Al composite, fabricated by powder metallurgy techniques, has been investigated. Instead of any special thermomechanical processing or hot rolling, simple hot extrusion has been employed to obtain a fine grained structure before superplastic testing. Superplastic tensile tests were performed at strain rates ranging from 10-2 to 10-4 s-1 and at temperatures from 833 to 893 K. A maximum elongation of 200% was achieved at a temperature of 853 K and an initial strain rate of 1.67×103 s-1. The highest value obtained for the strain rate sensitivity index (in) was 0.32. Differential scanning calorimeter was used to ascertain the possibility of any partial melting in the vicinity of optimum superplastic temperature. These results suggested that no liquid phase existed where maximum elongation was achieved and deformation took place entirely in the solid state.

Effect of tungsten carbide particles on microstructure and mechanical properties of Cu alloy composite bit matrix

Copper alloy composite bit matrix was prepared by pressureless vacuum infiltration,using at least one of the three kinds of tungsten carbide particles,for example,irregular cast tungsten carbide,monocrystalline tungsten carbide and sintered reduced tungsten carbide particles.The effects of powder particle morphology,particle size and mass fraction of tungsten carbide on the microstructure and mechanical properties of copper alloy composite were investigated by means of scanning electron microscopy,X-ray diffraction and abrasive wear test in detail.The results show that tungsten carbide morphology and particle size have obvious effects on the mechanical properties of copper alloy composites.Cast tungsten carbide partially dissolved in the copper alloy binding phase,and layers of Cu_(0.3)W_(0.5)Ni_(0.1)Mn_(0.1)C phase with a thickness of around 8–15μm were formed on the edge of the cast tungsten carbide.When 45%irregular crushed fine cast tungsten carbide and 15%monocrystalline cast tungsten carbide were used as the skeleton,satisfactory comprehensive performance of the reinforced copper alloy composite bit matrix was obtained,with the bending strength,impact toughness and hardness reaching 1048 MPa,4.95 J/cm^(2) and 43.6 HRC,respectively.The main wear mechanism was that the tungsten carbide particles firstly protruded from the friction surface after the copper alloy matrix was worn,and then peeled off from the matrix when further wear occurred.

Preparation and corrosion resistance of the micro-arc oxidation coating on Al_2O_3f/ZL109 composites

A ceramic layer was prepared on the surface of Al2O3f/ZL109 composites by means of micro-arc oxidation （MAO） technique. The surface morphology and phase constituent of the ceramic layer were analyzed using scanning electron microscope and X-ray diffraction. The polarization curves of the composites before and after MAO treatment were measured and analyzed. The results showed that after Al2O3f/ZL109 composites were treated using MAO technique in silicate solution, the ceramic layer formed, and it was composed of Al, Si, and mullite phase. Al and Si came from Al alloy matrix of the composites, and the mullite phase formed in process of MAO. Al2O3 fiber in the composites affects the electric conductivity of the composites, the MAO reaction is promoted, and the cera- mic layer forming on the composite material side is slightly thicker than that on the Al alloy side. After Al2O3f/ZL109 composites were treated using MAO technique, the corro- sion resistance of the composites is significantly improved.

Effects of the Composition of Electrodeposited Fe-Ni-P Alloy on the Thermostability and Magnetic Properties

The magnetic properties, structure defects of electrodeposited Fe-Ni-P alloys with various compositions and the thermostability at amorphous state have been studied by DSC, positron annihilation and electronic integrating instrument methods. The results show that the thermostability of amorphous Fe-Ni-P alloys increases with Fe content. Emergence and recrystallization of stable phases defer as the P content of the coating increases. The minimum H-c, B-r and P-h occur at 9.4 P (wt pet) content. Maximum H-c, B-r and P-h occur at the weight ratio of Fe to Ni equaling to 1/9.

Microstructure of Ni–Al powder and Ni–Al composite coatings prepared by twin-wire arc spraying

Ni–Al powder and Ni–Al composite coatings were fabricated by twin-wire arc spraying（TWAS）. The microstructures of Ni-5wt%Al powder and Ni-20wt%Al powder were characterized by scanning electronic microscopy（SEM） and energy dispersive spectroscopy（EDS）. The results showed that the obtained particle size ranged from 5 to 50 μm. The morphology of the Ni–Al powder showed that molten particles were composed of Ni solid solution, NiAl, Ni_3Al, Al_2O_3, and NiO. The Ni–Al phase and a small amount of Al_2O_3 particles changed the composition of the coating. The microstructures of the twin-wire-arc-sprayed Ni–Al composite coatings were characterized by SEM, EDS, X-ray diffraction（XRD）, and transmission electron microscopy（TEM）. The results showed that the main phase of the Ni-5wt%Al coating consisted of Ni solid solution and Ni Al in addition to a small amount of Al_2O_3. The main phase of the Ni-20wt%Al coating mainly consisted of Ni solid solution, Ni Al, and Ni_3Al in addition to a small amount of Al and Al_2O_3, and Ni Al and Ni_3Al intermetallic compounds effectively further improved the final wear property of the coatings. TEM analysis indicated that fine spherical NiAl_3 precipitates and a Ni–Al–O amorphous phase formed in the matrix of the Ni solid solution in the original state.

Influences of Composition and Annealing on the Martensitic Transformation in Ni-Fe-Ga Alloys

A series of Ni-Fe-Ga alloys near the prototype Heusler composition （X2YZ） were prepared through arc-melting suction-casting method. The dependences of the transformation behavior on the alloy composition and annealing treatment were studied in detail by an optical microscope, X-ray diffraction, and differential scanning calorimeters methods. The experimental results show that the martensitic transformation temperatures increase almost linearly with increasing Ni content in all the NiFeGa alloys. Annealing the Ni55.5Fe18Ga26.5 alloy at 100-500 ℃ for 3 h and at 300 ℃ for 1-10 h shifts the martensitic transformation start temperature by almost 20 ℃ to high temperature. The variations in the martensitic transformation temperatures in these alloys are discussed in terms of structural differences resulting from alloy composition and annealing treatment.

HIGH TEMPERATURE COMPOSITES

The purpose of this paper is to review the current state of development of new composite materials for advanced aircraft engines. The advantages and disadvantages of Ti-base.NiAl-base, and MoSi_2-base composites as replacements for today's Ni-base superalloys are discussed from the standpoint of key technical issues. current status, and future directions. Results describing progress in both improved understanding of the mechanisms of deformation and fracture, and improved material performance will be covered.

Composition Dependence and Irradation Effects on Residual Resistivity in Cu-Al Alloys

Residual electrical resistivity due to short-range order has been calculated for Cu100-xAlx (x=9.13,13.56, 14.5 and 14.76 in at pct) alloys using pseudopotential approach, and the results have been discussed in the light of experimental studies of the local-order structure of these alloys. In case of Cu85.5Al14.5, change in the total residual electrical resistivity due to neutron-irradiation effects has been estimated by including contributions from the short-range order and static atomic displacement correction. Our results show a decrease in the residual resistivity in the irradiated Cu-Al solid solution as compared to the unirradiated sample. This is in accordance with the experimental results

Composition and Structure of Ti-6Al-4V Alloy Plasma-based Ion Implanted with Nitrogen

The composition and structure of Ti 6Al 4V alloy plasma based ion implanted with nitrogen was investigated.The nitrogen depth distribution shows more antiballistic with distribution peak heightened with increased implantation time(dose),and more like a parabola at the low implantation pulse voltage.When implantation pulse voltage is increased,the implantation depth increased with the nitrogen distribution peak being deepened,widened and lowered somewhat.TiN,TiN+Ti 2N,or Ti 2N second phases were formed in the implanted layer.The relative percentage of nitrogen content in the form of TiN increases when going deeper into the implanted(TiN formed) layer.The increase of implantation pulse width and/or time is favourable for the formation of TiN rather than Ti 2N.It is unfavourable for formation of any nitrides when implantation pulse voltage is decreased to 30kV or less.Tiny crystalline particles (made mainly of Ti 2N and a smaller percentage of TiO 2 phases) of regular shapes such as triangle and tetragon, etc .(about 20 nm) are found distrbuted dispersively in the near surface region of samples implanted at the high implantation pulse voltage (75kV).