Serrated flow and abnormal strain rate sensitivity of a magnesium-lithium alloy

Tensile experiment of LA41 magnesium alloy was carried out and serrated flow was apparent throughout the deformation history. This alloy exhibited abnormal strain rate sensitivity (SRS); that is, SRS was positive in the strain rate range from 1.33 x 10(-4) s(-1) to 6.66 x 10(-4) s(-1), and became negative in another range from 6.66 x 10(-4) s(-1) to 1.33 x 10(-2) s(-1). The critical strain was observed to increase with increasing strain but decrease with increasing temperature. In addition, activation energy for serrated flow was calculated and variations of SRS were explained through the competition between dynamic strain aging (DSA) of solute atoms and shearing of precipitates by dislocations. (c) 2006 Published by Elsevier B.V.