Creep Behaviour of a y Ti - Al Intermetallic Alloy

The creep behaviour of a 1 mm thick sheet of a Ti – 46.5 Al –4(Cr, Nb, Ta, B) (at%) in the 600 – 800o C has been studied. Specimenswere machined in both the longitudinal and long transverse orientation ofthe sheet. No failure was produced, even after 2000 hours and understresses that represented 85% of the yield strength, in the specimens at 600oC and no sign of cavities was found in their whole gauge length. Asignificantly better creep performance of transverse specimens wasobserved in the whole temperature range. At higher temperatures specimensfailed after relatively short period times and in longitudinal specimenstested at 800o C and the higher stress level no real steady state creep wasobserved. Larson and Miller parameter has been used to fit experimentalresults and good correlations were found.