Papers by Keyword: SEM/EBSP Analysis

Abstract: Grain refinement and high temperature deformation in two kinds of magnesium alloys subjected to friction stir processing (FSP) have been investigated. One was a rolled sheet of LA141Mg and another was a cast plate of AZ91Mg. FSP was developed by adapting the concepts of friction stir welding to obtain a fine grain size in a stirred zone. Grain refinement was achieved by FSP to give fine grain sizes of 11.4μm and 8.4μm for LA141 and AZ91 alloys, respectively. For LA141 alloy, the maximum stress of the FSPed sample was higher than that of the as-received one in the range of 300K to 523K while the elongation to failure of the former was considerably smaller than that of the latter. On the other hand, the elongation for the FSPed sample of AZ91Mg showed three times larger elongation with a lower maximum stress than the as-received cast one at 523K and 2.8×10-3s-1. Further difference in high temperature deformation for both magnesium alloys was discussed based on microstructural change and stress-strain curves.

Abstract: Superplasticity and crystallographic orientation distribution of an Al-Mg-Mn sheet subjected to friction stir processing (FSP) have been investigated. The FSP was developed by adapting the concepts of friction stir welding to obtain a fine grain size in a stirred zone. Grain refinement was achieved by the FSP to give a smaller grain size of about 4µm than a value of 26µm in the as-received sheet. The SEM/EBSP analysis of the specimen before and after the FSP revealed a fraction of high angle grain boundaries became a higher percentage of 83% due to the FSP than 75% before. The elongation to failure in the FSPed sample had a maximum value of 361% at 773K and 1.1×10-3 s-1. Further, change in crystallographic orientation distribution is investigated during tensile testing in consideration of deformation mechanism.