Phase relationships involving TiC and Ti_3AlC (P phase) in Ti- Al - C system

摘要

Titanium rich alloys of the Ti - Al - C system have been investigated to determine the constitution in the range 1250 - 750 deg C with particular reference to phase equilibria and transformations involving TiC and Ti_3AlC (P phase). Alloys with varying aluminium and carbon concentrations up to 15 at.-percent Al and 15 at.-percent C have been studied using scanning and transmission electron microscopy and X-ray diffraction. The isothermal sections at 1250, 1050, 1000, and 750 deg C reported by previous workers are reviewed. Equilibria involving the phases #beta#-Ti, #alpha#-Ti, Ti_3Al (#alpha#2), TiC, and Ti_3AlC (P phase) have been investigated and partial isothermal sections at 1050 and 750 deg C are presented. A revision of the previously established Ti - Al - C isothermal section at 750 deg C is shown involving equilibria of #alpha# + #alpha#_2 + P and #alpha# + P + TiC. The orientation relationship between the P phase and Ti - Al (#alpha#/#alpha#_2) matrix has been found to be (0001)_(#alpha#/#alpha#_2)//{111}_p and <1210>(#alpha#/#alpha#_2)<110>_P.