Excess volume and heat of mixing in Cu-Ti liquid mixture.

Molar excess volume of Cu-Ti liquid mixture has been investigated to elucidate how the excess volume in binary alloys is related to mixing enthalpy and microscopic interactions. Cu-Ti is used as a key example for systems showing positive excess volume and negative mixing enthalpy. For this purpose, the density of several Cu-Ti binary mixtures has been measured over the whole composition range by the containerless technique of electromagnetic levitation as a function of temperature. A linear temperature dependence of the density has been found for all investigated alloys. In addition, the density decreases with increasing Ti content in the alloys, showing a negative deviation from the ideal solution model. As mentioned, a positive excess volume was found whereas the enthalpy of mixing is negative. This behavior has been discussed in relation with chemical ordering and the role played by attractive and repulsive interactions in the system, according to previous results obtained by means of molecular dynamics simulation on binary dense fluids.