Laser-flash calorimetry V. Effect of oxygen contamination on the heat capacity of vanadium from 80 to 850 K

Abstract

The heat capacity of vanadium with 0.33 mass per cent of O and with 1.11 mass per cent of O in solid solution has been measured by laser-flash calorimetry through the temperature region 80 to 850 K. Comparison of the results with earlier values for vanadium at and above ambient temperature and for vanadium and for a terminal solution alloy at very low temperatures shows that below about 450 K oxygen in solution depresses the heat capacity of vanadium by amounts which increase with increasing oxygen content. Above about 450 K, the heat capacities of vanadium and of the terminal solution alloys are comparable. This heat-capacity behavior results in differences between the entropies of vanadium and of terminal solution alloys which increase up to about 450 K and then remain relatively constant. These entropy differences are sufficiently large that, when multiplied by temperature to determine a Gibbs-energy contribution, the product is such as to indicate that very minor amounts of oxygen in vanadium may appreciably modify its alloying behavior.