Grain boundary premelting in thin foils of deformed copper bicrystals

Abstract

The grain boundary premelting temperature (GBPMT) T m in thin foils of 99.99 mass% copper bicrystals deformed in tension to a strain of 0.4 increased from approximately 0.5 T M up to near the bulk melting point T M with increasing oxidation time. The GBPMT T m in thin foils of the bicrystal whose grain boundary plane was parallel to active screw dislocations was lower than that to active edge dislocations. The difference between the GBPMT in 99.99 and 99.9999 mass% copper polycrystals were not so significant. The difference between the GBPMT T m(Al)[ ≑ T M(Al)] of aluminum bicrystals and the T m(Cu)[ ≑ 0.5T M(Cu)] of copper bicrystals depends upon the difference between the properties of the corresponding oxide films and would probably be related to the difference in the elastic anisotropy between them. Plastic strain would decrease the GBPMT at least in copper.