Thermal stability refers to the ability of a material to resist the action of heat energy by maintaining its mechanical properties like strength, toughness, and ductility). In general, a material is considered thermally stable if it does not decompose under the influence of temperature. The thermal stability of a substance can be determined using a thermogravimetric analyzer (TGA) . One way to measure thermal stability is to determine the temperature at which the material starts to decompose or react, along with the extent of mass change determined using thermogravimetry. The absence of reaction or decomposition is used as an indicator for thermal stability.

Thermal stability is an important design characteristic for engineering materials used at elevated temperatures). It may be defined as the resistance of an alloy to degradation of ductility and toughness when subjected to long-term thermal exposure). One common measurement of thermal stability is residual room temperature tensile elongation following such exposure). Another common measurement of thermal stability is residual room temperature impact strength following long-term exposure at elevated temperatures).

In summary, thermal stability is the ability of a material to resist decomposition or degradation under the influence of temperature, and it is an important characteristic for materials used at elevated temperatures.