HIGH-TEMPERATURE MECHANICAL-PROPERTIES OF ALMGZN ALLOYS WITH COPPER AND ZIRCONIUM ADDITIONS

High temperature mechanical properties of AlMgZn alloys grain refined by zirconium were investigated by impression creep and tensile tests. The strain rate sensitivities and activation energies obtained are pre sented. It has been found that the steady-state impression creep rate is strongly influenced by Cu and Zr addition. The simultaneous additio n of Cu and Zr resulted in fine-grained microstructure due to which th e material exhibited superplastic properties at high temperatures. Tog ether with the superplastic behaviour the occurrence of a threshold st ress has also been observed.