Nano-sized Ag-Cu 8nm /AlN 10nm multilayers were deposited by reactive DC sputtering on a-Al 2 O 3 (0001) substrates. Investigation of the phase constitution and interface structure of the multilayers evidences a phase separation of the alloy sublayers into nanosized grains of Ag and Cu. The interfaces between the Ag grains and the quasi-single-crystalline AlN sublayers are semicoherent, whereas the corresponding Cu/AlN interfaces are incoherent. The orientation relationship between Ag and AlN is constant throughout the entire multilayer stack. These observations are consistent with atomistic models of the interfaces as obtained by ab initio calculations. V C 2012 American Institute of Physics.[http://dx.
crease of the constitutive yield and ultimate stresses for thinner joints. In the present case, a surface inspection of the test specimen showed that these trends could be mostly imputed to the increase of the residual porosity after the manufacturing of the smaller joints, demonstrating by the way the strong influence of the processing parameters on the constitutive properties of lead-free solder alloys. The effects of plastic constraints were studied by comparing the apparent (constrained) and constitutive (unconstrained) stress-strain curves. Important constraining effects were observed, with a 35 % increase of the ultimate stress of the thinner joints due solely to the plastic constraints and the evolution of the constraining effects with the gap width showed a dependency in the form of (1/Gap) 2/3 . Finally, with the chosen joint geometry, the increase of yield and ultimate stress due to plastic constraints was shown to completely dominate the decrease due to size effects and manufacturing quality.Si 3 N 4 -TiN ceramics exhibit an excellent thermo-mechanical and tribological behaviour even in corrosive environments. In particular, they offer a unique set of properties for different applications when combined with high load-bearing metallic materials such as steels. Our current interest is the potential application of the joints of Si 3 N 4 -TiN ceramics with case hardenable steels for components in the cutting tools industry.The main problem when brazing ceramic parts is their poor wetting by most metals and alloys. Because of the different surface energies of the solid ceramic and of the liquid metal there is no thermodynamic driving force for the wetting. This can be solved by adding active elements to the COMMUNICATIONS ADVANCED ENGINEERING MATERIALS 2006, 8, No. 3
The design and construction of a high-pressure (200 bar) and high-temperature (600 degrees C) heat-flow differential scanning calorimeter (DSC) for the in situ investigation of the hydrogenation and dehydrogenation reactions of hydrides is presented. In combination with a pressure-concentration-temperature (pcT) system, simultaneous thermodynamic and volumetric measurements become accessible. Due to the high thermal conductivity of hydrogen, only the sample cell and the reference cell are exposed to hydrogen and the remaining system is under ambient conditions. This separation has the advantage that the calibration factor is independent of the hydrogen pressure. The internal empty volume of the combined system is as low as possible to maximize the precision of the pcT measurements. The calorimetric block of the DSC is designed with a silver/copper alloy and the temperature measurements are made resistively with platinum temperature sensors (Pt 100). The instrument was calibrated and its operability was successfully studied on the example of the hydrogen sorption behavior of LaNi(5).
In the present work, the applicability of the copper free silver based alloys Ag-15Mn and Ag-5Pd as filler metals for shielding gas brazing of the martensitic stainless steel X3CrNiMo13-4 was investigated. The joints were examined with respect to their microstructure, their corrosion behaviour in aequous NaCl solution as well as -in the case of the specimens brazed with AgPd5their mechanical performance under tensile and torsion loading. Specimens brazed with Ag-15Mn showed pronounced oxidation in the Ar/H 2 shielding gas atmosphere as well as a low corrosion resistance in 0?5M NaCl solution. The filler metal Ag-5Pd showed very good brazing results. With this filler metal, defect free and corrosion resistant joints with an ultimate tensile strength of 800 MPa and a low cycle fatigue strength of 490 MPa could be produced.
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