Investigation of the Site Occupation of Atoms in Pure and Doped TiA1/Ti3Al Intermetallic

Dual-phase TiAl/Ti₃Al alloys consisting of a lamellar structure, comprising gamma-phase plus a small amount of alpha₂ -phase, with addition of 1, 5 and 10 at.%Nb or 2 at.%Ag were prepared. The samples were investigated by means of the field ion microscopy (FIM), the tomographic atom probe (TAP) and supporting TEM, HRTEM analysis. The influence of doping elements on the variation of the field evaporation and microstructural parameters in the gamma-phase as studied by FIM and TAP will be reported in this contribution. A new algorithmic approach based on TAP results was developed to evaluate the site occupancies in such ordered structures. In addition, computer modelling and simulation of the field evaporation behaviour of the different species including the next neighbour interaction in a FIM specimen are performed for the first time