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Alloy Samples (alloy + sample)
Selected AbstractsDependence of Ductility on Free Volume in a Cu-Zr-Based Metallic Glass,ADVANCED ENGINEERING MATERIALS, Issue 3 2009Feng Jiang Cu46Zr47Al7 bulk metallic glass alloy samples with different free volume states were obtained through thermal treatments such as annealing and quenching. Three-point bending tests were performed to these samples to evaluate their ductility. The results demonstrate that the ductility of BMGs is closely related to the free volume. The reduction in the free volume is the dominant reason for the embrittlement of samples annealed below Tg. In addition, the ductility of embrittled samples can be enhanced by restoring free volume by a short anneals above Tg followed by quenching. [source] In vitro evaluation of the effect of a current bleaching agent on the electrochemical corrosion of dental alloysJOURNAL OF ORAL REHABILITATION, Issue 10 2002enay Canay summary, The nightguard bleaching of discoloured teeth is currently performed by using % 10 carbamide peroxide. While the material is effective on the bleaching of natural teeth, it may deteriorate crowns, bridges and amalgam restorations placed in the mouth. The purpose of the present study was to investigate the effect of 10% carbamide peroxide on the electrochemical corrosion of various dental casting alloys used for fixed partial dentures and dental amalgam. Tafel extrapolation curves were obtained by the corrosion cell that facilitated simulation of the oral enviroment and comparison of the corrosion rates of alloys and amalgam was accomplished. The results revealed that unpolished amalgam and nickel-chromium alloy samples had the most and noble alloys had the least corrosion rate. [source] The entrapment of corrosion products from CoCr implant alloys in the deposits of calcium phosphate: A comparison of serum, synovial fluid, albumin, EDTA, and waterJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 8 2006A. C. Lewis Abstract Physical wear of orthopedic implants is inevitable. CoCr alloy samples, typically used in joint reconstruction, corrode rapidly after removal of the protective oxide layer. The behavior of CoCr pellets immersed in human serum, foetal bovine serum (FBS), synovial fluid, albumin in phosphate-buffered saline (PBS), EDTA in PBS, and water were studied using X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). The difference in the corrosive nature of human serum, water, albumin in PBS and synovial fluid after 5 days of immersion was highlighted by the oxide layer, which was respectively 15, 3.5, 1.5, and 1.5 nm thick. The thickness of an additional calcium phosphate deposit from human serum and synovial fluid was 40 and 2 nm, respectively. Co and Cr ions migrated from the bulk metal surface and were trapped in this deposit by the phosphate anion. This may account for the composition of wear debris from CoCr orthopedic implants, which is known to consist predominantly of hydroxy-phosphate compounds. Known components of synovial fluid including proteoglycans, pyrophosphates, phospholipids, lubricin, and superficial zone protein (SZP), have been identified as possible causes for the lack of significant calcium phosphate deposition in this environment. Circulation of these compounds around the whole implant may inhibit calcium phosphate deposition. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:1587,1596, 2006 [source] Effects of Hf content and immersion time on electrochemical behavior of biomedical Ti-22Nb- xHf alloys in 0.9% NaCl solutionMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 5 2009B. L. Wang Abstract The aim of this study was to investigate the effects of Hf content and immersion time on the electrochemical corrosion behavior of the Ti-22Nb- xHf (x,=,0, 2, 4, and 6 at%) alloy samples in 0.9% NaCl solution at 37,°C and neutral pH range, utilizing the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. From the polarization curves, all these alloys exhibited typical passive behavior, which was indicated by a wide passive region without the breakdown of the passive films and low corrosion current densities. In addition, the values of the corrosion current densities and passive current densities decreased with increase in the Hf content. The EIS results, fitted by RS(QPRP) model, exhibited capacitive behavior (high corrosion resistance) with phase angles closed to ,80° and high impedance values at low and medium frequencies, indicating the formation of a highly stable film on these alloys in the test solution. The resistance of the passive films improved with increase in the Hf content and immersion time. All these observations suggested a more noble electrochemical behavior of the Ti-22Nb- xHf alloys compared to the Ti-Nb binary alloy. [source] Study of the mechanical and thermal properties of Sn,5 wt% Sb solder alloy at two annealing temperaturesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003M. M. EL-Bahay Abstract Sn,5 wt% Sb alloy is one of the materials considered for replacing lead-containing alloys for soldering in electronic packaging. Differential thermal analysis (DTA) and specific heat of the sample were studied. Wetting contact angle measurements of the alloy on different substrates were carried out at high temperature. Microhardness tests as a function of temperature were performed to calculate the effective activation energy of the solder alloy Sn,Sb and compared with the pure elements Sn and Sb. Isothermal creep curves for alloy samples were obtained under different constant applied stresses at different working temperatures ranging from 463 K to 503 K, followed by annealing the samples at two different temperatures before and above the threshold value (Tm/2). The transient creep parameters and the values of the stress exponent n were calculated for the two annealing temperatures. Microstructure examinations of the as-cast alloy at room temperature and after the two annealing treatments with the effect of the cold work deformation and creep test on the structure change and properties of Sn,Sb alloys were reported. The stress rupture test was also measured. [source] Determination of the band-gap of MgS and MgS-rich Zn1,xMgxSySe1,y alloys from optical transmission measurementsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2010Ian A. Davidson Abstract As part of our development of an epitaxial lift-off process, utilising a sacrificial magnesium sulphide (MgS) layer, we have developed a MgS-rich ZnMgSSe alloy which provides excellent carrier confinement and resists both oxidation and acid attack. Here the optical transmission of the alloy has been measured and its bandgap determined as a direct transition at 4.19,±,0.04,eV. Its composition has also been determined by X-ray interference (XRI) and comparison with simulations. For a range of alloy samples we obtain compositions of the Zn1,xMgxSySe1,y layers which are (x, y),=,(0.80,±,0.02, 0.645,±,0.025). Using the alloy bandgap and composition we have determined direct bandgap transition energy for MgS by extrapolation. This is found to be 4.78,±,0.14,eV. [source] The Coupling Effect of Small Nanocrystals and Free Volume on the Ductility of Cu46Zr47Al7 Bulk Metallic Glass Alloy,ADVANCED ENGINEERING MATERIALS, Issue 5 2009Feng Jiang Cu46Zr47Al7 bulk metallic glass (BMG) and its composite containing small in situ precipitated nanocrystals were prepared through copper mold casting. Different free volume states of these Cu46Zr47Al7 alloys were obtained through thermal treatment such as annealing and quenching. Three-point bending tests for these alloys were undertaken to evaluate their plastic deformation ability. Free volume changes were measured indirectly but quantitatively with differential scanning calorimetry (DSC) method. The results show that, the ductility of Cu46Zr47Al7 alloys is closely related with the free volume states and the ductility of thermally embrittled Cu46Zr47Al7 alloys samples can be partially recovered by restoring free volume through quenching process. The presence of small nanocrystals is more efficient than free volume to enhance the ductility. However, only with the concurrence of the small nanocrystals and the free volume, the Cu46Zr47Al7 BMG alloys will present excellent ductility. [source] | |||||||||||||