80 research outputs found

    Peak Stir Zone Temperatures during Friction Stir Processing

    Get PDF
    The stir zone (SZ) temperature cycle was measured during the friction stir processing (FSP) of NiAl bronze plates. The FSP was conducted using a tool design with a smooth concave shoulder and a 12.7-mm step-spiral pin. Temperature sensing was accomplished using sheathed thermocouples embedded in the tool path within the plates, while simultaneous optical pyrometry measurements of surface temperatures were also obtained. Peak SZ temperatures were 990 ⁰Cto 1015 ⁰C (0.90 to 0.97 TMelt) and were not affected by preheating to 400⁰C, although the dwell time above 900 ⁰C was increased by the preheating. Thermocouple data suggested little variation in peak temperature across the SZ, although thermocouples initially located on the advancing sides and at the centerlines of the tool traverses were displaced to the retreating sides, precluding direct assessment of the temperature variation across the SZ. Microstructure-based estimates of local peak SZ temperatures have been made on these and on other similarly processed materials. Altogether, the peak-temperature determinations from these different measurement techniques are in close agreement

    Use of a trabecular metal implant in ankle arthrodesis after failed total ankle replacement: A short-term follow-up of 13 patients

    Get PDF
    Patients and methods 13 patients with a migrated or loose total ankle implant underwent arthrodesis with the use of a retrograde intramedullary nail through a trabecular metal Tibial Cone. The mean follow-up time was 1.4 (0.6-3.4) years. Results At the last examination, 7 patients were pain-free, while 5 had some residual pain but were satisfied with the procedure. 1 patient was dissatisfied and experienced pain and swelling when walking. The implant-bone interfaces showed no radiographic zones or gaps in any patient, indicating union. Interpretation The method is a new way of simplifying and overcoming some of the problems of performing arthrodesis after failed total ankle replacement

    The Morphology, Crystallography, and Chemistry of Phases in Wire-Arc Additively Manufactured Nickel Aluminum Bronze

    No full text
    A new Wire-Arc Additive Manufacturing (WAAM) technique is used to produce Nickel Aluminum Bronze (NAB) components for marine applications in view to mitigate the problems that typically arise in a cast microstructure. In cast condition, the alloy typically exhibits microstructure that consists of an FCC Cu-rich solid solution (or α-phase), some retained β-phase, and several intermetallic phases collectively referred to as κ-phase. This study aims to characterize the crystal structures of the various κ-phases or precipitates, their distribution, morphology, orientation relationships with the α-matrix, and their chemical compositions in WAAM-NAB alloy using electron microscopy. The precipitation of κ-phase differs in morphology and chemical composition to those present in a cast NAB. In addition, some uniaxial tensile coupons were machined out of the WAAM-NAB samples, where tensile mechanical properties are superior to those of cast NAB. The effects of microstructural differences in both alloys on the mechanical properties are correlated
    corecore