Pulse-Annealing for the Study of Relaxation Processes in Solids

Abstract

A new experimental technique is presented for studying rate processes in solids. The method, termed ``pulse‐annealing,'' involves direct heating of a very small sample to a chosen annealing temperature for a short period, followed by rapid cooling to some fixed temperature for an in‐place physical property measurement. The method is a very flexible one, as the above cycle may be repeated to obtain any desired time‐temperature history. General experimental techniques are described and specific application to graphite and metals noted. The annealing process is examined theoretically. A method is described for deriving the activation energy of the fundamental relaxation process from the isothermal annealing curves of a physical property, the physical property being used as an index of the annealing process. It is shown that the activation energy is derivable without knowledge of the relation between the measured physical property and the fundamental kinetic variable. For further kinetic analysis (determination of rate constants and orders of reaction), however, it is necessary to know this relation. The analysis of isothermal and tempering experiments is compared.