Deformation behavior of a 2219 Al alloy

Abstract

The deformation behavior of a 2219 aluminum alloy was studied in the temperature range from 250 to 500 °C. The results, which cover four orders of magnitude in strain rate, show an increasing apparent stress exponent and an increasing apparent activation energy with decreasing temperature. It is shown that the 2219 aluminum alloy exhibits threshold behavior, like aluminum alloys produced via powder metallurgy technique. The introduction of a threshold stress into the analysis leads to stress exponent of ∼7 and a true activation energy of about 90 kJ mol −1 in the temperature range 250–450 °C. At T=500 °C, the true stress exponent, n, is equal to 5 and true activation energy is equal to 143 kJ mol −1. The normalized threshold stress exhibits a strong temperature dependence. The value of the energy term, Q o, is about 35 kJ mol −1 in the temperature range 250–450 °C and tends to decrease at higher temperature. The operating deformation mechanism is discussed in terms of the transition from low temperature climb to high temperature climb with increasing temperature.