the maximum extrusion speed of 20 ft min for the ze20 alloy is about 25 higher than the maximum extrusion speed of 15 ft min for the az31 alloy indicating higher productivity for the new ze20 alloy to analyze the microstructure characteristics of the extruded tubes polished samples sectioned parallel and normal to the extrusion axis were prepared by first scraping 0 50 m off the leading end of the extruded tube to ensure that the material being examined represents a portion of the tube formed by way of steady state extrusion next metallographic samples of the type needed were prepared and polished by standard methods the samples were then etched in a solution containing 20 ml glacial acetic acid 50 ml picric acid 10 ml methanol and 10 ml de ionized water polished samples cut parallel and normal to the extrusion axis were fabricated from both extruded rods and examined with a nikon u2122 optical microscope interfaced with a leco u2122 image analyzer to inspect the microstructure in both the longitudinal and transverse directions samples were also subjected to electron probe micro analysis epma using a cameca sx100 electron probe microanalyzer to identify the metallurgical phases in the microstructure the optical micrographs showed no anisotropy in grain morphology along either direction and indicate a fully recrystallized nearly equi axed grain structure with an average grain size of approximately 30 u03bcm for the az91 sample and 45 u03bcm for the ze20 ze40 and ze60 samples zinc in the magnesium solid solution is a major strengthening.