Tensile and compressive deformation behavior of the Al-Si-Cu-Mg cast alloy with additions of Zr, V and Ti

The deformation behavior of the Al-Si-Cu-Mg cast alloy with micro-additions of Zr, V, and Ti was investigated under uniaxial tension and compression. It was found that after T6 heat treatment the change of the load from tension to compression caused an increase in strength from 348 MPa to 417 MPa and in fracture strain from 1.3% to 37.0%. As calculated based on Mott's theory of strain hardening, the dislocation slip distance in compression was twice of that in tension. The observed differences in alloy fracture strain were explained by changes in re-orientation and fracturing of the eutectic silicon particles. Due to deformation, fracturing of the silicon particles occurred with major cracks being parallel to the compression axis but perpendicular to the tensile load axis. An influence of deformation mode on change in orientation of the silicon particles was revealed. While for tensile load, the silicon particles were stationary during deformation and exhibited an orientation practically the same as in unstrained structure, for compression there was a substantial change in the particle orientation, especially for an angle between the load axis and the particle axis in the range from 0° to 30°.