THE TI-N SYSTEM - KINETIC, CALORIMETRIC, STRUCTURAL AND METALLURGICAL INVESTIGATIONS OF THE DELTA'-TIN0.51 PHASE

The transformation of the quenched delta'-TiNx phase, with values of x between 0.5 and 0.6, into delta-TiN0.51 was investigated using the heat treatment of two types of TiNx homogeneous bulk samples produced by nitrogen diffusion into titanium plates (45 x 10 x 0.4 mm3) and strips (100 x 10 x 0.12 mm3). The transformation of quenched delta-TiN(x) was investigated using electrical resistance measurements, differential scanning calorimetry (DSC), differential thermal analysis (DTA), X-ray diffraction and metallography. The transformation quenched delta --> delta' was complete for the composition 33.8 +/- 0.5 at.% N, with DELTA = -64 J g-1. The delta'. The delta' phase splits up on a peritictoid at 800 +/- 10-degrees-C according to the reaction delta' half-arrow-right-over-half-arrow-left-epsilon + delta. A partial Ti-N equilibrium diagram is proposed.