Coupled thermodynamic/kinetic analysis of diffusional transformations during laser hardening and laser welding

Employing a Tian-Calvet-type calorimeter operating in the scanning mode at temperatures from 1120 to 1220 K, the enthalpy change, DELTAdH, associated with the decomposition of GaBO3 (=1/2beta-Ga2O3+1/2B2O3(liq.)) and the corresponding decomposition temperature, Td, were determined: deltadH=30.34±0.6 kJ/mol, Td=1190±5 K. Using the transposedtemperature-drop method the thermal enthalpy, H(T)-H(295 K), of GaBO3 was measured as a function of temperature, T, in the region from 760 to 1610 K; the results obtained are