Advanced Materials Research Vols. 535-537

Abstract: Nickel-cobalt alloys have broad application prospect for their excellent properties (i.e. high microhardness, strength, abrasion, corrosion resistance and magnetic properties.etc). Present situation and new trends on mechanism of the anomalous codeposition and technology of electrodepostion of nickel-cobalt were studied. Effects of electrolysis parameters (e.g. concentration of co2+in the electrolyte, cathodic current density, pH value, temperature.etc) on the alloy composition, morphology and mechanical properties were analyzed. The formation of the monovalent intermediate (hydroxides or colloid) may cause the cobalt preferential deposition or the faster charge-transfer of Co2+ reduction compared to that of Ni2+ reduction is the main factor that causes the anomalous codeposition behavior of the nickel-cobalt alloy.

Abstract: Hot compressive deformation tests of burn resistant titanium alloy (Ti-35V-15Cr-Si-C) with initially as-cast and as-extruded microstructure were performed at deformation temperature between 900°C to 1200°C for as-cast and 900°C to 1150°C for as-extruded alloy, and strain rates between 10^-3 s^-1 to 1s^-1. The compressive true stress vs. true strain curves were measured, the deformation activation energy was calculated and the microstructures after deformation were studied. The results show that dynamic reversion is the primary soften mechanism of the burn resistant titanium alloy during hot deformation. At the higher strain rate ( =1s^-1), the ‘Necklace’ Dynamic Recrystallization will occur for as-cast alloy, and a Continuous Recrystallization will occur for as-extruded alloy. At the lower strain rates, both as-cast and as-extruded burn resistant titanium alloy display the continuous recrystallization. The extruded alloy presents larger dynamic recrystallization regions than that of the as-cast alloy.

Abstract: Copper molybdenum ore, Experiment study, Copper molybdenum separation, Flotation. Abstract. Aimed at the ore characteristics，the flotation flowsheet of one—stage coarse grinding—bulk flotation of copper and molybdenum—regrinding of bulk concentrate—separation of copper and molybdenum was determined effected．Experiment uses the above flowsheet and reasonable conditions to process molybdenum crude ore of molybdenum and copper crude grade being 0.066% and 0.03%,and the better indexes of the molybdenum grade of concentrate is 51.68%,the copper grade of concentrate is 12.60% and molybdenum recovery is 74.33% are got.

Abstract: Effect of content of Fe,Si and Fe/Si on Structure and Properties of 3014 can-body were studied by using tensile test, stamping test, SEM, XRD, etc. The results show that:(1) The sum of Cube and Goss texture in 3104 aluminum-alloy canbody is about 40%. The influence of brass texture{011}, S texture{123}, copper texture Cu{112}, cube texture{001} and Goss texture{011} is balanced, resulting in ears in 8 directions and low earing rate. Fe/Si of 1.8 possesses less content of Brass compared to Fe/Si of 3.2 ，and less earing rate; (2)The phase size of compound particles of Al(Fe,Mn,Si) in the second phase of 3104 aluminum-alloy canbody shouldn’t exceed 22μm, Lumpy compound particles will compromise the life of moulds.

Abstract: Titanium and titanium alloys have been widely employed in many load-bearing orthopaedic applications due to their excellent strength and corrosion resistance. However, postimplantation infections might occur even though considerable studies have been made. Choosing a bio-friendly alloying element is one way to reduce infection risk. The aim of this study is to evaluate the extent of bacterial attachment on titanium, tantalum, niobium and tin surfaces. Two pathogenic bacterial strains, namely Staphylococcus aureus CIP 65.8T and Pseudomonas aeruginosa ATCC 9027, were used in this study. Quantification of bacterial attachment was performed using scanning electron microscopy. Results indicated that the surface chemistry and topography of the investigated materials significantly influence the degree of P. aeruginosa and S. aureus adhesion; however, surface wettability did not show a significant impact upon bacterial retention. In this study, tin was shown to be the most attractive material for bacteria adhesion but tantalum limits the bacterial adhesion. Therefore, it is suggested to limit the amount of tin as an titanium alloying element due to its nature to attract P. aeruginosa and S. aureus adhesion.

Abstract: In this study, the effect of KBF4 addition on the microstructure of the Mg-6Zn-1Si alloy has been investigated by Optical Microscopy (OM), Scanning Electron Microscopy (SEM) with Energy Dispersive Spectrometer(EDS). At 1.5wt% KBF4 addition, the morphology of Mg2Si phase completely changed from Chinese script type into uniformly, dispersedly distributed graininess or small block, with the average size of the Mg-6Zn-1Si alloy decreasing from 135μm to 82μm.

Abstract: First-principles supercell calculations based on density functional theory were performed to study the site preference behavior and elastic properties of 3d (Ti-Cu) transition-metal elements in B2 ductility YAg alloy. It is found that Ti occupies the Y sublattice, while V, Cr, Co, Fe, Ni and Cu tend to substitute for Ag site. All alloying elements can decrease the lattice parameters of Y8Ag8, among which Y7Ag8Ti shows the largest change. Furthermore, the calculated elastic constants show that Cr, Fe, Co and Cu can improve the ductility of YAg alloy, and Y8Ag7Fe presents the most ductility among these alloy, while Ti and Ni alloying elements reduce the ductility of YAg alloy, especially, V transforms ductile into brittle for YAg alloy. In addition, both V and Ni can increase the hardness of YAg alloy, and Y8Ag7V is harder than Y8Ag7Ni.

Abstract: In-situ TiB₂ particles reinforced AA7055 composites were fabricated through mixed-salts route and their bending properties were studied. The composites reinforced with 5 wt % and 10 wt% TiB2 exhibit higher bending strength than the unreinforced matrix alloy. The improvement in bending strength may be attributed to dislocation strengthening, Orowan strengthening, and grain strengthening. The good bonding between the reinforcements and the matrix also plays an important role.

Abstract: Co-based ODS alloys strengthened by γ΄ precipitates and nanosized oxides are promising high-temperature structural materials. Single solid solution of Al and W in the matrix can not be achieved after mechanical alloying, resulting in the formation of low volume fraction of γ΄ phase and several kinds of secondary phases. The addition of Ni promotes the precipitation of γ΄ phase and reduces the amount of secondary phases by the enlargement of the solid solution limit of Al and W within the matrix. In comparison with the lower fracture strength and cleavage fracture mode of the alloy without the addition of Ni, Ni-containing Co-base ODS alloys exhibit much higher fracture strength and obvious ductile facture mode.

Abstract: The effect of cobalt on the structural properties of intermetallic Tb₃(Fe_28-xCo_x)V_1.0 with Nd₃(Fe,Ti)₂₉ structure has been studied by using interatomic pair potentials obtained through the lattice inversion method. Calculated results show that the order of site preference of cobalt is 8j(Fe8), 4e(Fe11) and 2c(Fe1) which is in good agreement with experimental results. And the calculated lattice constants coincide quite well with experimental values. All these prove the effectiveness of interatomic pair potentials obtained through the lattice inversion method in the description of rare-earth materials.