Compaction, sintering and mechanical properties of elemental 6061 Al powder with and without sintering aids

Compaction, sintering, microstructural and mechanical properties of the premixed (elemental) 6061 Al powder with and without sintering aids were investigated. The highest green densities (∼2.6 g/cm3) were obtained at a compaction pressure of ∼510 MPa. The optimum sintering condition was at a temperature of 620 °C for 1 h under pure nitrogen for compaction pressures of 340 or 510 MPa. It was found that additions of ∼0.12 wt% Pb was the most effective and enhanced the sintering response by obtaining almost a full sintered density (∼2.7 g/cm3) with a corresponding increase in the hardness and tensile strength values as compared to the base 6061 Al alloy powder mixture without Pb addition. Additions of ∼0.1 and 0.4 wt% Sn or Ag, respectively, also improved the sinterability of the elemental base powder with sintered densities of ∼96–98% theoretical (∼2.65 g/cm3). The highest UTS value of ∼322 MPa with yield strength of ∼250 MPa and 9% elongation to failure were obtained for the nitrogen sintered and fully heat-treated (T6) 6061 Al alloy with addition of 0.6 wt% paraffin wax as lubricant and 0.12 wt% Pb as sintering aid.