Effect of titanium in aluminium matrix on densification and forming limit of P/M composites during upsetting process

Abstract

The present work investigates the densification and forming limit of sintered porous aluminium–titanium preforms for various relative densities and titanium particles. The compacts of 1 aspect ratio with 2–6% of titanium contents in aluminium matrix for various relative densities were prepared through powder metallurgy route by applying suitable powder forming pressures. A sequence of the cold upsetting test has been carried out using 0.5 MN capacity of hydraulic press machine at 0.1 s−1 strain rate. The relation between true axial strain and preforms relative density was plotted, and the influence of titanium and relative density on the densification curve was investigated at various compaction pressures. The specimen properties like apparent strain hardening exponent (na) and apparent strength coefficient (Ka) was determined through stepwise incremental deformation tests. The critical transition density (CTD) vide forming limit diagram was determined from the plot of na and Ka concerning the preforms relative density, and it was found to be 85.9%, 87.7% and 88% for 2%, 4% and 6% of titanium in the aluminium matrix. The CTD values of porous aluminium–titanium preforms were compared with those of the previous work of porous aluminium–copper preforms under the same compositions. Also, the average grain size of the components was determined and it is observed that 2% of titanium contains a larger grain size compared to other compositions. Hence, a higher forming limit was obtained in 2% of titanium reinforced with aluminium matrix.