Sample records for alloy-in-738

  1. Effects of temperature and Al-concentration on formation mechanism of an aluminide coating applied on super alloy IN738LC through a single-step high activity gas diffusion process

    International Nuclear Information System (INIS)

    Formation mechanism of an aluminide coating on a nickel base superalloy IN738LC via a single step high activity gas diffusion process has been investigated in this research. Effects of coating temperature and aluminum concentration in powder mixture on formation mechanism were studied using optical and scanning electron microscopes, energy-dispersive X-ray spectroscopy and X-ray diffraction techniques. For this purpose two different packs containing 1 and 2 wtpercentaluminum powder, were used for coating the samples at two temperatures, 850degreeC and l050degreeC. The ratio of Al to activator was kept constant in both packs. By increasing the Al content in high activity powder mixture, the concentration of diffused Al increased in the coating layers, and the thickness of coating increased. At 1050degreeC as the rate of diffused Al to the interdiffusion zone increased, this zone gradually transformed to outer coating phases. At 850degreeC coating formed by inward diffusion of Al, but at 1050degreeC it was initially formed by inward diffusion of Al followed by outward diffusion of Ni.

  2. Influence of different etchants on the representation of microstructures in nickel alloys; Einfluss verschiedener Aetzmittel auf die Gefuegedarstellung in Nickellegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Speicher, Magdalena; Scheck, Rudi; Maile, Karl [Stuttgart Univ. (Germany). Materialpruefungsanstalt


    This work presents a comparison of selected nickel alloys of the same condition which were treated by means of specifically chosen etching techniques. Microstructures on microscope images of wrought Alloy 617, a casting variant of Alloy 625, a polycrystalline casting alloy IN-738 LC, as well as of a monocrystalline superalloy CM 247 LC SX, respectively, are juxtaposed and evaluated. This approach allows for a comprehensive optical microscopy characterization of the characteristic microstructural features.

  3. Analysis and description of the long-term creep behaviour of high-temperature gas turbine materials. Ermittlung und Beschreibung des Langzeitkriechverhaltens hochwarmfester Gasturbinenwerkstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, H.


    On a series of standard high-temperature gas turbine materials, creep tests were accomplished with the aim to obtain improved data on the long-term creep behaviour. The tests were carried out in the range of the main application temperatures of the materials and in the range of low stresses and elongations similar to operation conditions. They lasted about 5000 to 16000 h at maximum. At all important temperatures additional annealing tests lasting up to about 10000 h were carried out for the determination of a material-induced structure contraction. Thermal tension tests were effected for the description of elastoplastic short-time behaviour. As typical selection of materials the nickel investment casting alloys IN-738 LC, IN-939 and Udimet 500 for industrial turbine blades, IN-100 for aviation turbine blades and IN-713 C for integrally cast wheels of exhaust gas turbochargers were investigated, and also the nickel forge alloy Inconel 718 for industrial and aviation turbine disks and Nimonic 101 for industrial turbine blades and finally the cobalt alloy FSC 414 for guide blades and heat accumulation segments of industrial gas turbines. The creep tests were started on long-period individual creep testing machines with high strain measuring accuracy and economically continued on long-period multispecimen creep testing machines with long duration of test. The test results of this mixed test method were first subjected to a conventional evaluation in logarithmic time yield and creep diagrams which besides creep strength curves provided creep stress limit curves down to 0.2% residual strain.

  4. Thermo-mechanical fatigue behaviour of the near-{gamma}-titanium aluminide alloy TNB-V5 under uniaxial and multiaxial loading

    Energy Technology Data Exchange (ETDEWEB)

    Brookes, Stephen Peter


    -strain history. The effects of TMF on the microstructure were also investigated. For all types of tests intergranular fracture is predominant. Failure is strongly influenced by environmental conditions. This study compares TMF results of TiAl with previous TMF investigations on the nickel-based alloys IN 738 and Nimonic 90. IN 738 shows similar TMF behaviour to {gamma}-TiAl in that uniaxial IP loading has the longest fatigue lifetimes. Nimonic 90 shows the opposite behaviour to both of these alloys. A lifetime model developed for this near-{gamma}-TiAl alloy, successfully describes all temperaturestrain TMF loading conditions over the test temperature range, with the use of a single loading parameter. The loading parameter is based on the plastic work per cycle, and is not only dependant on the mean tensile stress but also on the maximum principal stress. The loading parameter responds to various strain-temperature-paths differently. It describes the lifetime relation between uniaxial IP and OP loading, axial and torsional loading and the hold period effect. (orig.)