Discrepancies of the Invar Alloy Thermal Expansion Specifications of Military Specification MIL-I-23011C (AMS-I-23011)

The thermal expansion specifications of the Invar alloy of military specification MIL-I-23011C (AMS-I-23011) were reviewed in relation to the thermal expansion behavior of the Invar alloy produced by Allegheny Ludlum, an unnamed producer, and Krupp VDM. The military specification was also compared to the thermal expansion specifications of the American Society for Testing and Materials (ASTM), B 753 and F 1684. It was determined that the thermal expansion specifications of MIL-I-23011C (AMS-I-23011) are erroneous. This conclusion recognizes that the military appears not to have utilized the National Institute of Standards and Technology (NIST) standard reference materials (SRMs) for the specification development.