EFFECT OF METALLURGICAL PARAMETERS ON THE PERFORMANCE OF Al-2%Cu-BASED ALLOYS

The present study was performed on a recently developed Al-Cu alloy, designed for automotive applications. This alloy has the composition Al-2%Cu-1.32%Si-0.42%Mg-0.58%Fe-0.59%Mn-0.07%Ti. It was determined that the alloy containing (0.5% Zr + 0.15% Ti) was the most effective in maximizing the alloy tensile strength over the range of aging temperatures studied, from 155 to 300 degrees C. The addition of Ag is beneficial at high aging temperatures, in the range of 240-300 degrees C when added simultaneously with 0.27 wt% Zr. However, it is less effective when compared to a high Zr concentration (about 0.62 wt%) at the same levels of Ti. It is concluded that the alloy tensile properties may be determined by contributions from different strengthening mechanisms, namely the grain size, the volume fraction of intermetallics produced, and evolution and growth of the hardening precipitates with respect to the aging conditions. Quality charts constructed from the tensile data may be used to select the appropriate metallurgical conditions for tailoring the alloy properties to those required for a specific application. Increasing the copper content from 2 to 3.5 wt% does not produce a significant increase in the alloy strength. However, it increases the calculated alloy density from approximately 2.78 to 2.93 g/cm(3).