Formation and interesting thermal expansion behavior of novel Sm-based bulk metallic glasses

Two kinds of Sm-based alloys, Sm55Al25Co20 and Sm55Al25Cu10Co10, have been cast into full glassy rods up to 4 and 3 mm in diameter, respectively, by copper mold casting. The substitution of 10 at% Co for 10 at% Cu leads to the increase in glass forming ability and thermal stability of the Sm55Al25Co20 bulk metallic glass (BMG). An interesting phenomenon is observed that Sm-based BMGs exhibit different thermal expansion behaviors compared to previously studied Cu-based BMGs above the glass transition temperature. The phenomenon correlates to the degree of contraction for the sample in the supercooled liquid region.