Revision of the Ti-N phase diagram as probed by neutron diffraction

Full-profile (Rietveld) analysis of neutron diffraction patterns was used to show that the homogeneity ranges of a tetragonal phase E >-Ti(2)N(1 - x) and an ordered tetragonal phase delta'-Ti(2)N(2x) phase of the Ti-N system lie within 0.38 a parts per thousand currency sign N/Ti a parts per thousand currency sign 0.42 and 0.45 a parts per thousand currency sign N/Ti a parts per thousand currency sign 0.50, respectively. Unit cell parameters were determined for E > and delta' phases at the lower and upper boundaries of the homogeneity ranges. A cubic nitride phase having a short-range order in the nitrogen arrangement was shown to exist in the concentration range 0.45 a parts per thousand currency sign N/Ti a parts per thousand currency sign 0.75 at relatively high temperatures. The short range order transforms to a long-range order below 800 K in the concentration range 0.45 a parts per thousand currency sign N/Ti a parts per thousand currency sign 0.50. Phase transition features in titanium nitride were determined for the concentration range TiN(0.45)-TiN(0.50). A revised version of a fragment of the Ti-N phase diagram was proposed proceeding from the formation conditions and the existence ranges of the delta' and E > phases and on the basis of literature data.