Deformation behavior of an Al-3.37 wt pct Li alloy

Al-3.37 wt pct Li alloy was deformed by differential strain rate and constant initial strain rate test techniques to investigate deformation and failure behavior over the strain rate range of 10(-5) to 10(-2) s(-1) and the temperature range of 22 degrees C to 580 degrees C. Flow stress first increases then decreases with an increase in test temperature, whereas ductility shows a sigmoidal relationship with the test temperature. The maximum ductility of about 80 pct is obtained at intermediate strain rate and 550 degrees C. Failure is noted to occur by cavity interlinkage and crack formation. Strain rate sensitivity (m) and activation energy (Q) for deformation are determined to be 0.04 to 0.13 and 96.2 to 157.4 kJ/mol, respectively. Toward lower test temperatures, both the m and Q are found to have lower values. Deformation at high temperature is suggested to be controlled by dislocation climb. However, under non-steady-state conditions due to cavitation, m and Q both vary with strain