Date: December 2013
Creator: Dendge, Nilesh Bajirao
Description: Magnesium alloys are the lightweight structural materials with high strength to weigh ratio that permits their application in fuel economy sensitive automobile industries. Among the several flavors of of Mg-alloys, precipitation hardenable Mg-rare earth (RE) based alloys have shown good potential due to their favorable creep resistance within a wide window of operating temperatures ranging from 150°C to 300°C. A key aspect of Mg-RE alloys is the presence of precipitate phases that leads to strengthening of such alloys. Several notable works, in literature, have been done to examine the formation of such precipitate phases. However, there are very few studies that evaluated the effect stress induced deformation on the precipitation in Mg-RE alloys. Therefore, the objective of this work is to examine influence of deformation on the precipitation of Mg-Nd based alloys. To address this problem, precipitation in two Mg-Nd based alloys, subjected to two different deformation conditions, and was examined via transmission electron microscopy (TEM) and atom probe tomography (APT). In first deformation condition, Md-2.6wt%Nd alloy was subjected to creep deformation (90MPa / 177ºC) to failure. Effect of stress-induced deformation was examined by comparing and contrasting with precipitation in non-creep tested specimens subjected to isothermal annealing (at 177ºC). In ...
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