ASTM E3518-25

1.1 This practice provides recommended reference values for the first-order melting temperatures and enthalpies (heats) for selected materials that may be used for the calibration, confirmation, or evaluation of thermal analytical methods, apparatus, or software over the temperature range of –90 °C to 2000 °C.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

4.1 The Gibbs phase rule informs us that the temperature of a pure substance remains constant during first-order transitions such as melting. This characteristic, along with the enthalpy (heat) associated with that transition, is used in a number of thermoanalytical test methods to calibrate apparatus or to confirm performance. It is the purpose of this practice to provide “best estimate” first-order (melting) temperature and enthalpy values for selected materials that may be used for this purpose.