Abstract: At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T.sub.1 phase (Al.sub.2 CuLi). This addition enhances the nucleation of the precipitate T.sub.1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell Hardness values and confirmed by standard tensile tests.

Abstract: An improved mechanical extensometer for use with a constant load creep test machine 10, wherein the dead weight of the extensometer is counterbalanced by two pairs of weights 70,90 and 80,100 connected through a pulley system 68, 78, 88 and 98 to rod extension 55,56 and 59,60, leading into the furnace 20 where test sample S is undergoing elevated temperature (above 500.degree. F.) tensile testing. Novel gripper surfaces, conical tip 119 and flat surface 122, are provided in each sample engaging platens 38 and 40 to reduce the grip pressure normally required for attachment of the extensometer to the specimen and reduce initial specimen bending normally associated with foil-gage metal testing.