Interparticle movement and the mechanical behavior of extruded powder aluminum at elevated temperature

摘要

This paper proposes a model and a mechanism for explaining the mechanical behavior of extruded powder aluminum at elevated temperature. This behavior is significantly different from that of ingot-cast and drawn aluminum which is subjected to the same tests. Powder aluminum exhibits a strain-softening effect which is evident in a decrease of stress with increasing strain in uniaxial test specimens when the experiment proceeds into the postyield region. Similar behavior is observed in the shear response during biaxial tension-torsion loading. For these tests, the shear stress is additionally reduced with increased axial extension. A model and mechanism are proposed, based on the relative motion of the extruded aluminum particles, to explain this effect. Equations are derived which relate the axial and shear stresses and strains. These equations are fitted to data obtained in a matrix of experiments, which include combined loadings from uniaxial tension to simple shear. Results are presented graphically and are in good agreement with the proposed models. [References: 21]