Constitutive flow behavior and hot workability of powder metallurgy processed 20 vol.%SiCP/2024Al composite

Constitutive flow behavior and hot workability of the powder metallurgy processed 20 vol.%SiCP/2024Al composite were investigated using hot compression tests. The modified Arrhenius-type constitutive equations were presented with the values of material constants in consideration as a function of strain. Dynamic material model (DMM) and modified DMM were used to construct the power dissipation efficiency maps, and Ziegler's instability criterion and Gegel's stability criterion were used to build instability maps. The presence of finer SiCP and more boundaries resulting from smaller 2024Al powders shifted the dynamic recrystallization domain of the 2024Al matrix to higher strain rate and lower temperature ranges and decreased the peak value of power dissipation efficiency. Large instable regions were found in the form of flow localization and cavitations located at the matrix/SiCP interfaces and within the SiCP clusters. By comparison, the Gegel's stability criterion was more sensitive to the instability zones than the Ziegler's instability criterion for this material.

Research highlights▶ Constitutive equations considering flow softening behavior are constructed. ▶ Finer SiCP and smaller 2024Al powders change the DRX conditions. ▶ Gegel's instability criteria predict large regions of instability.