EFFECT OF EXTRUSION PARAMETERS ON THE MICROSTRUCTURE AND PROPERTIES OF AN AL-LI-MG-ZR ALLOY

The effect of the extrusion temperature and the extrusion ratio on the microstructure and mechanical properties of an Al Li-Mg Zr alloy in the as-extruded, solution-treated and aged conditions were investigated. It was found that an increase in the extrusion temperature and ratio increased the degree of recrystallization in the extrudate. An increase ih the extrusion temperature also increased the sub-grain size, whereas the extrusion ratio did not affect the sub-grain size. The strength of the extrudates decreased and the ductility increased in the as-extruded condition with increases in the extrusion temperature and the extrusion ratio. However, in the solution-treated condition, although the effect of the extrusion ratio on the mechanical properties was found to be the same as in the as-extruded condition, the trend with the extrusion temperature changes and the extrusion temperature was not simple in its influence on the mechanical properties. The fracture toughness remained almost unaffected by variation either in the extrusion temperature or the extrusion ratio.