THERMOSONIMETRY OF THE NBS-ICTA TEMPERATURE STANDARDS

Thermosonimetry (TS) curves for the NBS-ICTA recommended DTA temperature standards (NBS standard references materials 759 and 760) are reported. These materials generally show two regions of TS activity. The first (lower temperature) region is associated with a variety of processes such as fluid inclusion release, grain boundary motions and microcrack propagation, whereas the second (higher temperature) region is associated with the polymorphic transformations. Incorporation of a DTA specimen holder assembly into the TS equipment has provided evidence that the temperatures of the peak TS activity in the transformation regions correspond to the extrapolated onset temperatures of the DTA peaks, suggesting that the polymorphic transformations provide these crystals with mechanisms for relief of mechanical strain. © 1979.