INTERPARTICLE MOVEMENT AND THE MECHANICAL-BEHAVIOR OF EXTRUDED POWDERALUMINUM AT ELEVATED-TEMPERATURE

This paper proposes a model and a mechanism for explaining the mechani cal 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 exhibi ts 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 th e shear response during biaxial tension-torsion loading. For these tes ts, the shear stress is additionally reduced with increased axial exte nsion. A model and mechanism are proposed, based on the relative motio n of the extruded aluminum particles, to explain this effect. Equation s are derived which relate the axial and shear stresses and strains. T hese 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.