SILICIDE PRECIPITATION STRENGTHENED TIAL

Precipitation of a titanium silicide Ti5Si3 was found to be beneficial to improvement of the creep resistance of a fully lamellar Ti-4SAl-1.5Cr cast alloy without the sacrifice of tensile properties. The addition of 0.26-0.65 mol% Si generates fine precipitates less than 200 nm in size during aging at 900 degrees C for 5 h. The precipitates are effective obstacles to dislocation motion and raise the stress exponents of power law creep significantly. The specific creep strength of Si-containing alloys is better than that of a conventional Ni-base cast superalloy Inconel 713C at 800 degrees C for 10000 h.