A low-temperature modification to the Charpy impact test, with an example study of the fracture toughness of Mg-12%Li between 4.2 to 77 K

A modification to the Charpy test for measuring impact fracture toughness h as been developed that permits the specimen to be bathed in flowing liquid helium while mounted on the testing machine's anvil immediately prior to im pact. This method permits samples to be tested at any temperature between 4 .2 and 77 K, which extends the Charpy test to temperatures lower than those achievable by the conventional liquid bath immersion technique. A body-cen tered cubic Mg-12%Li single-phase alloy was tested by this new method and f ound to have anomalously high impact fracture toughness in the temperature range 4.2 to 77 K.