Abstract: A gas turbine engine including a core having a compressor section fluidly connected to a combustor via a primary flowpath and a turbine section connected to the combustor via the core flow path. An assembly is disposed within the gas turbine engine and includes a first part connected to a second part via a radial stack joint. The first part includes a radially inward facing surface contacting a corresponding radially outward facing surface of the second part. A fastener protrudes through the first part and the second part and is configured to maintain the relative positions of the first part and the second part. A channel is disposed on at least one of the radially inward facing surfaces and is positioned between the fastener and a circumferential edge of the first part. The channel is connected to at least one cooling air source.

Abstract: Nitrogen-strengthened alloys, especially steels, are produced by heating a combination of metal particles and a nitrogen donor, such as a chromium nitride, to make nitrogen available as a solute in the particles. The particles may be produced as a permeable preform for the process. The dissolved nitrogen leads to improved hardness, and higher strength is additionally obtained by the inclusion of a dispersant, such as yttria, in the particles.

Abstract: Nitride dispersion strengthening of stainless steel or nickel-based alloys is achieved by mechanically alloying the constituents of the alloy together with a nitride former, such as titanium, and a nitrogen donor, such as chromium nitride, and heating the mechanically alloyed powder to dissociate the donor and combine the resulting nitride with the nitride former. The heating step may be carried out in the course of hot consolidating the powder, e.g. by extrusion.

Abstract: To increase the creep strength of a titanium-containing alloy which also contains chromium, the alloy powder is heated in the presence of ammonia at a temperature of the order of 700.degree. C. so as to form a layer of chromium nitride(s) on the particles and is then heated further in an inert atmosphere at a temperature between 1000.degree. C. and 1150.degree. C. to dissociate the chromium nitride(s) thereby effecting nitriding of the titanium to titanium nitride which affords dispersion-strengthening of the alloy.