MECHANICAL-BEHAVIOR OF FINE-GRAINED MG-6.5LI AT ELEVATED-TEMPERATURE

A Mg-6.5 wt. % Li alloy containing 80% hcp alpha phase and 20% bcc beta phase was processed to achieve an average grain size of 5.9 mum. Strain-rate-change tests were performed in the temperature range from 398 K to 573 K. Two types of creep behavior were observed. A stress exponent of five, obtained at low temperatures and high stresses, is attributed to a diffusion-controlled dislocation creep process in the alpha matrix. A stress exponent of three, obtained at high temperatures and low stresses, is attributed to a solute-drag controlled dislocation creep process in the alpha matrix.