Heat capacity of VT1-0 commercial titanium and VT5 and VT5-1 titanium base alloys at low temperature

The temperature dependences of the heat capacity of commercial titanium VT1-0 and alloys on its base, VT5 and VT5-1, have been derived in the temperature range of 4 to 290 K. For comparison, similar measurements have been conducted on pure titanium and specially prepared solid solutions on its base (Ti+3.7 at.% Al and Ti+0.82 at.% Sn). The measurement accuracy has been sufficient for comparing the results with calculation data. The obtained results are interpreted using the known concepts of the role of the mass of interstitial atoms and changes in the interatomic bond forces. It is shown that the phonon components of the molar heat capacities of solid solutions of Al in titanium have lower values in the entire temperature range, as compared to titanium. The corresponding differences are proportional to the Al concentrations. The lower molar heat capacity in the case of dissolution of Al is due to the low mass of the impurity atoms and stronger interatomic bonds in their neighbourhood. The trend of the temperature dependence curve of the heat capacity of a more complex alloy VT5-1 may be interpreted as a result of superimposition of two effects: contribution of the Al impurity which decreases the heat capacity and the contribution of a heavier tin impurity Which increases the heat capacity in the low-temperature region. The effects of heat capacity variation, observed in binary alloys made of pure metals, are also manifested in the case of commercial alloys of a more complex composition (VT5, VT5-1)