Residual Stresses in Two‐Phase Systems as Determined by Changes in Transition Temperature

Differences in thermal expansion between glass and crystal and between halide and oxide produce hydrostatic and nonhydrostatic pressures (negative or positive) in polyphase bodies which result in marked changes in the phase‐transition temperature of one of the phases. In the glass‐plus‐crystal systems, the tensile strength of the matrix is not exceeded and reasonable agreement between calculated and experimental values is obtained. The magnitude of maximum lowering in the transition temperature of a particular system is shown to be in the hundreds of degrees centigrade. In a crystalline halide matrix, high tensile stresses cause fractures in the halide and therefore substantial discrepancies between the experimental and calculated values.