Constant Stress Creep of XD™ TiAl Containing Nitrogen

Abstract

AbstractTi-47at%Al+7vol%(TiN+TiB2) alloys, produced by the Martin Marietta XD™ process, were subjected to tensile constant stress creep deformation in the range 760-850°C temperature and 138–276 MPa (20–40 ksi) stress. These alloys have a matrix of TiAl and Ti3Al initially containing 1 to 10 μm diameter equiaxed particles of Ti2B and Ti2AlN. Microstructures were examined using optical, SEM and TEM methods in an attempt to correlate the substructures with the property data. In particular, fine coherent particles have been observed to decorate dislocations and the interior of TiAl grains. The presence of these particles is thought to explain the creep resistance of this alloy.