  Effect of site-selective substitution of Ti in Cu on the thermal stability of
CuTi alloy is investigated using classical molecular dynamics simulations with
Embedded Atom Method potentials. It has been observed experimentally that
melting point of all the naturally occurring stable phases of CuTi alloys do
not show a definite trend with gradual increase in Ti concentration. To
understand the phenomenon, super cells of CuTi alloy are constructed where Cu
atom is substituted by Ti randomly and at selective sites. For random
substitution, the melting point decreases linearly with increase in Ti
concentration. A non-monotonous dependence is seen when Cu atoms at selective
sites are replaced by Ti. For a particular doping concentration, the melting
point shows a wide range of variation depending on the order of atomic
arrangement, and can be fine tuned by selecting the sites for substitution. The
variations in melting points in different cases are explained in terms of the
peak height, width and position of the corresponding radial distribution
functions. Finally, it is verified that initial structures of the naturally
occurring CuTi alloys are responsible for the non-definite trend in their
melting points.
