Impression Creep Behaviour of U−6%Zr Alloy: Role of Microstructure

Creep behavior of U−6%Zr alloy was studied in the temperature range 550−650 °C using impression creep technique. Creep curves at 575 °C for various stresses are not smooth and exhibited some waviness. Sometimes creep curves show a sudden penetration of the punch which is followed by decrease in impression depth with time. The punching stress versus creep rate data for the above temperature also show a random behaviour. A detailed microstructural investigation was carried out with the help of SEM and EDX to understand this phenomenon. At creep testing temperature, δ-UZr2 phase continuously forms and it takes very long time to complete the reaction. Hence, the reason for waviness may be due to the formation of δ-phase coming out from the supersaturated α-phase.