Effects of Grain Size and Microcracking on the Thermal Diffusivity of MgTi ₂ O ₅

Abstract

The laser flash technique was used to study the effect of grain size on the thermal diffusivity of polycrystalline MgTi 2 O 5 from 25° to 800°C. Microcracking decreased the thermal diffusivity by as much as a factor of two with the decrease increasing with increasing grain size. When specimens were heated then cooled, the thermal diffusivity exhibited a horizontal flat figure‐eight hysteresis. This hysteresis, which appeared to be a function of the thermal history, was attributed to a balance between crack healing, or closure, at high temperatures and the growth of existing cracks or the formation of new cracks during cooling.