A dilatometric study of platinum during repeated quenching

The increase in length of platinum of 99.9% purity has been examined during repeated quenching in air.In the initial region of thermal fatigue at constant quenching temperature, the total and irreversible component were found to be linear functions of the number of quenchings and the reversible part remained constant. The activation enthalpy of vacancy formation determined from thermal fatigue characteristics (i.e. from the dependence of the total increase in length on the quench number) wasH _v ^f =(1.41±0.04) eV.