Metal-ceramic composites via in-situ methods

Chapter 2 – The eutectic solidification process

The processing and microstructural characteristics of nickel-based superalloys obtained by high-power laser surface cladding were studied. The processing variables were laser power, scan velocity and the composition of the feeder powder. The initial compositions consisted of a mixture of NiCrAl (71/18/11% by weight) and NiCrAl plus zirconium oxide composite (66/16/12/4% by weight). Following the process, the clad layers were characterized using analytical tools such as optical and scanning electron microscopy and thickness, substrate/ coating interface, cracks and their hardness.

Laser cladding of high-temperature coatings

Failure of a low pressure turbine rotor blade of an aeroengine

Microstructure and intermediate-temperature mechanical properties of powder metallurgy Ti–6Al–4V alloy prepared by the prealloyed approach

The major components of gas turbines and their materials requirements are outlined. The properties, advantages, and limitations of materials which have been and are being used in gas turbines are then described in the following groups: aluminium alloys, magnesium alloys, titanium and its alloys, steels, and finally nickel- and cobalt-base alloys. The applications of the last group of alloys and the importance of their metallurgical stability in turbine blades, discs, nozzle guide vanes, and sheet metal components are discussed. Corrosion and its prevention are then considered, followed by sections on experimental materials including alloys of chromium and the refractory metals, ceramics, and fibre composites. Future trends and prospects are discussed briefly in a concluding section.

J. E. Northwood

Papers

Materials for Gas Turbines